NATIONAL INSTITUTE OF GENETICSJAPANANNUAL REPORT
1956

No.7

Published by

THE NATIONAL INSTITUTE OF GENETICS
Misima, Sizuoka-ken, Japan
1957

•

1

Annual Reportof theNational Institute of Genetics
No.7,

1956

Published by

The National Institute of Genetics, Japan
1957

Exhibition of Japanese Morning Glory".

One of the colorful exhibits arranged for the benefit of foreig.lscientists attending the International Genetics Symposia was the display (by Dr. Y. Takenaka) of numerous varieties of Japanese morning glory, in which hundreds of different genotypes are being studied
and maintained at this Institute. The visitors were deeply impressedby the rich and varied color patterns of flowers in full bloom. In thispicture, Dr. Kihara, Director, is taking Dr. O. Winge of Sweden,around the exhibits.

CONTENTS
General statement .. .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. .. . . . . . . .. . . . . . . . .
Abstracts of diary for 1956
. . . . . . . .. .. .. . . . . . . . . . . . . .. .. . . .. . .
Staff
"
,
" .. .. .. .. .. ..
CouncilResearch program for 1956 ~ . . . . . . . . . . . . . .. . . . . .. .. .. . . .. .. .. .. . . . . . .
Foreign visitors in 1956
Researches carried out in 1956: . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . .
A.

B.

7

9
9
9
10

Equilibrium of human genes (KaMAl)......................
Population genetics of albinism (TANAKA, K)......................
Variation in taste-response to "citbittol" among the people of Misima(OGAWA et aI.)

Genetics and cytology of mammals, birds and insects
On the origin of the tortoiseshell male cat (KOMAI)
Studies on the mitotic index in various organs of the rat (ISHIHARA)
Resistance to blackhead disease of hybrid chickens (KAWAHARA)....
Quantitative relationship between autosomes and sex chromosomes ina few related species within the Coleopteran and Hemipteran groups
of insects (YosIDA)'" . . . .. . . . . .. . . ..

Cytology and genetics of tumors
9.
10.
11 .
12.

D.

4
5

Human genetics .. . . .. .. . . .. .. .. .. . . . . . . .. . . . . . . . . . . .. .. . . . . . .

8.

,

3

1.
2.
3.

4.
5.
6.
7.

C.

1

2

Change of chromosome constitution in stem-line of the YOSIDA sarcoma (YOSIDA)
Subtriploid chromosome constitution characteristic of the tumor stemcells of WALKER carcinosarcoma of rats (YOSIDA)..................
Occurrence of distinct V-chromosomes in cells of seven original
rat hepatomas (YOSIDA and ISHIHARA)..............................
A study on the transplantability of the WPY-rat sarcoma (ISHIHARA
and YOSIDA)
Effects of kinetin upon division of "Yoshida-sarcoma" cells (OGAWA,
ABE and FUJIOKA)

Genetics and biochemistry of the silkworm and other insects.. . .
13.
14.
15.

Genetics of the silkworm (TANAKA, Y.)............................
Effect of day-length during the embryonal stage of a wild silkworm,
Antheraea pernyi, on the pupal diapause (TANAKA, Y.)............
Effect of cytoplasm upon the expression of quantitative charactersin the silkworm (TAZIMA, MIDORIKAWA and SHIOKAWA) . . . . . . . . . . . .

10
12
12
13
14

15
16
16
18
19
21
21
23

23
24
25

ii

CONTENTS
16.
17.

Studies on the complex NI-U-Di loci in the silkworm (TSUJITA) ....
Genetical and biochemical studies on the yellow lethal silkworm, VI.
Chitin production and melanin metabolism (TSUJITA and SAKAGUCHI)
Genetical and biochemical studies on the metabolism of pteridines
in insects (NAWA, SAKAGUCHI and TAIRA).
Microdetermination of uric acid in Drosophila melanogaster duringmetamorphosis (TAIRA and NAWA)
.

18.
19.

Genetics and cytology of cereal crops and related plant groups ..

E.

20.
21.

27
31
32
35
36
36

Studies on the substitution and restoration of the nucleus (KIHARA)
Cytogenetical studies on F 1 hybrids of Agropyron with Triticum andAegilops (MATSUMURA, MURAMATSU and SAKAMOTO).
Complementary dominant lethal genes in rice (OKA).
.
Genetic basis of hybrid break-down in rice (OKA)
Hypothesis of "duplicate fertility genes" in rice (OKA).
Karyosystematic studies in Poaceae, IV (TATEOKA)
.

36
37
38
39
41

F. Cytology and genetics of Nicotiana and some other flowering plants

42

22.
23.
24.
25.

26.
27.
28.

29.
30.
31.
32.

Cytogenetic studies on the genus Nicotiana, IX. (TAKENAKA, AMANO
and TATEOKA).
Cytological studies in Euphorbiaceae, I. Chromosome numbers ofsome Euphorbian (SHIM OYAMA).
Genetics of the photoperiodic behavior of the Japanese morning
glory, Pharbitis nil Chois, II. Sensitivity of F 1 plants to dark period(SAKAMOTO).
Crossing experiments with Citrullus vulgaris SCHRAD. and C. colocynthis SCHRAD. (FURUSATO and MIYAZAWA).
Dextrality and sinistrality in plants (LILIENFELD and KIHARA).
An attempt to use disease-resistant American varieties in triploidy
breeding of sugar beets (MATSUMURA).
How to improve seed production of triploid sugar beets (MATSUMURA and SAKAMOTO).

Genetics and biochemistry of pigments and other substances inplants
.

G.

33.
34.
35.
36.

H.

Anthocyanin in the fruit-coat of two varieties of egg-plant, Burmaand Black beauty (ABE and GOTOH).
Further studies on paper chromatography of anthocyanins: Examination of glycoside types by partial hydrolysis (ABE and HAyASHI) ....
Dominance relationships of flower color in varietal F 1 hybrids of
Swiss Giant pansy, Viola tricolor maxima HORT. (ENDO).
Chemistry of the bitter substance in the fruits of Citrullus colocynthis SCHRAD. (OGAWA, ENDO and ABE).

Population genetics and studies on quantitative characters
37.

Genetic basis of polymorphism (KOMAI)

.
.

42
44

44
45
47
47
48

49
49
50
50
51
53
53

,

CONTENTS
38.
39.
40.
41.
42.
43.

I.

Statistical studies on the breeding behavior of wild populations of
Setaria pumila (SAKAI and IYAMA)
Genetical studies on the cherry-red leaf in tobacco plants (SAKAI
and IYAMA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Change of genetic variance in quantitative characters due to change
of gene frequency in hybrid rice populations (OKA) ............•...
A method to estimate the effect of linkages between polygenes in
autogamous plants (OKA)
Genotypic correlations among five economic characters in egg-plant(GOTOH)
Genetic variation in heading date in a local variety of barley,"Aokei No. 14" (GOTOH)

Studies on the technique of breeding

iii

53
55
58
60
62
63
64

44.

Method of estimation and use of genetic correlation in forest-tree
breeding (SAKAI)
45. ,Application of the coefficient of relationship in the breeding of autogamous plants (SAKAI)

65

J. Studies on competition and migration.. .. .. .. .. .. .. .. .. .. .. .. ..

67

46.
47.
48.
49.

50.

K.

Radiation genetics in animals
51.
52.
53.

,

54.
55.

L.

Competition between different species and species hybrids in Nicotiana (SAKAI and NARISE)
Competitive ability of barley varieties at various fertility levels of
the soil (SAKAI and OKA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Correlation between competitive ability and other characters in hybrid
populations of rice (OKA and SAKAI)
Experimental studies on migration using" population-tubes" in astrain of Drosophila melanogaster (SAKAI, NARISE, HIRAIZUMI and
IYAMA)............................................................
Migration studies in several wild strains of Drosophila rnelanogaster(SAKAI, NARISE and IYAMA)......
Effect of external irradiation with fl-rays upon the germ-cells of thesilkworm (TAZIMA) ..
..
Genic control of X-ray sensitivity of silkworm germ-cells (TAZIMA)
Chronic gamma irradiation of mice at different developmental stages
and its effect upon the breeding behavior (SUGAHARA, TUTIKAWA and
SUGIURA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Radiosensitivity of various mice strains (SUGAHARA, SUGJURA andHASHIMOTO)
The effects of X-irradiation on nitrogen metabolism in Drosophila.
melanogaster (TAIRA and NAWA)

Radiation genetics in plants
56.

Genetic effects of ionizing radiation in Einkorn wheat (MATSUMURA
and FUJII)

64

67
68
70

72
73
76
76
78

80
82
83
84
84

iv

CONTENTS
57.

58.
59.

M.

Effects of X· and r-radiations upon wheat seedlings and their modification due to temperature and polyploidy (MATSUMURA, FUJII and
KONDO)
Mutants in tobacco plants induced by X-rays and their application(MATSUMURA and FUJII)
Studies on chlorophyll mutants in diploid wheat induced by radiation(FUJII)

Genetics and cytology of microorganisms and viruses .. . . . . . . . .

Transductional analysis of phase variation in Salmonella (lINO and
LEDERBERG)
61. Electron microscopy of thin-sectioned nuclei in Paramecium (TsuJITA, WATANABE and TSUDA)

86
87
88
89

60.

N.

Mathematical genetics
62.
63.
64.
65.
66.

O.

, .. .. ..

Random genetic drift in a tri-allelic locus; exact solution with acontinuous model (KIMURA)
Selection in a finite population (case of complete dominance) (KIMURA)
Probability distribution of gene frequencies in natural populations(KIMURA)..........................................................
The rate of change of population fitness by natural selection(KIMURA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A model of a genetic system which leads to closer linkage by
natural selection (KIMURA)

Technical notes
67.
68.

Dosimetry of gamma rays with glass (KONDO)......................
Thermodynamical fundamental equation for spherical interface(KONDO)

Books and papers published in 1956 by staff members

89
91
93
93
94
95
96
97
98
98
100

101

GENERAL STATEMENT•

During this fiscal year there was no change either in the number of
departments or in the established number of staff members. Our institutecontinues to comprise six departments and fourteen laboratories. At
present we have thirty-eight research members including part-time members
and associates.
There were some changes in the personnel of our staff. On April I,
Dr. K. Hayashi was transferred as professor of botany to the Tokyo
University of Education; he was succeeded on September 1 by Dr. Y.
Ogawa. To our great regret, Dr. Y. Tanaka and Dr. T. Komai retired
on December 15. We are greatly indebted to both for the many inestimable services rendered to the newly established institute, especiallyin the difficult period of shaping our organization. They will remain incontact with our institute as research associates. Dr. Y. Tanaka was
succeeded by Dr. Y. Tajima on December 11; Dr. T. Komai's position isstill vacant.
A new concrete building, eighty tsubo in floor dimensions, planned forgenetic studies on microorganisms, is under construction. It will becompleted in March 1957.
During the current year four staff members went to U.S.A. partly on
scholarships, partly as laboratory assistants. Their names, destinations
and times of departure are:
Mr. Y. Yamada, Purdue University, April,
Dr. K. Gotoh, Iowa State College, June,
Mr. K. Tutikawa, Jackson Laboratory, October,Dr. M. Tsujita, Columbia University, October.
Mr. 1. Iino received a leave of absence for another year.
Dr. H. Oka was teaching in Formosa for six months; he returned in
March.
Dr. M. Kimura returned in August from U.S.A. after a three year
sojourn in Ames and Wisconsin; he obtained the Ph. D. degree from the
University of Wisconsin. He was also awarded a similar D. Sc. degree
by Osaka University.
The Rockefeller Foundation bestowed on the institute a grant of $10,000
for the purchase of literature. Until now 28 books and 17 periodicals(with 372 back numbers) have been bought.
Dr. R. Goldschmidt has sent us 628 reprints, two books and 10 periodicals (comprising 93 issues). Since 1951, Dr. Goldschmidt continues tosend us the publications which he is receiving, contributing greatly to ourlibrary.

ABSTRACTS OF DIARY FOR 1956

2

We have had the pleasure of welcoming many guests from abroad.
Many of them gave us interesting lectures on their special subjects.
Their list is given on p. 7.
During the International Symposia of 1956, 120 participants visited
Misima on September 11. They arrived at the institute around 10 o'clockin the morning coming from Hakone where they stayed overnight. The
main event arranged for the guests was an exhibit of the Japanese Morning
Glory. About 5,000 plants were kept in pots and in the field, and greatcare was taken to adjust the time of their flowering to this occasion. Approximately 100 mutants were on display. Later, all the participants wereinvited for lunch in Rakuju-En park by the mayor of Misima. Unfortunately Mt. Fuji remained invisible, since the day was at first rainy andlater cloudy.

•

ABSTRACTS OF DIARY FOR 1956
Jan.

7.

19.
4.
6.
15.
25.
Mar. 6.
10.
17.
25.
Feb.

Apr. 14.
21.
May 9.
25.
June

6.
28.
29.
July 3.
16.
Aug. 4.
4.
9.
9.
27.

Meeting of Subcommittee in charge of the arrangement of lectures for
the International Genetics Symposia.
45th meeting of Misima Geneticists' Club.
Public Lectures on Genetics (In the Hall of the Asahi Press. Tokyo).
46th meeting of Misima Geneticists' Club.
14th meeting of Board of Councillors.
47th meeting of Misima Geneticists' Club.
48th meeting of Misima Geneticists' Club.
Meeting of Tobacco Research Workers.
49th meeting of Misima Geneticists' Club.
The radio-isotope laboratory with an irradiation room of C060. underconstruction since last year. was completed.
Meeting of Preparation Committee of the International Genetics Symposia.
Meeting of Cancer Research Workers.
50th meeting of Misima Geneticists' Club.
Board meeting of Association for the Propagation of the Knowledge ofGenetics.
14th meeting of Biological Symposia.
Board meeting of Japan Association of Poultry Genetics.
General meeting of Japan Association of Poultry Genetics.
51st meeting of Misima Geneticists' Club.
Meeting of Tobacco Research Workers.
52nd meeting of Misima Geneticists' Club.
Meeting of Editorial Board of "The Heredity" (Iden).
15th meeting of Board of Councillors.
15th meeting of Biological Symposia.
16th meeting of Biological Symposia.

..

STAFF

3

Meeting of Committee for Exhibit on Japanese Morning Glory.
Exhibition of Japanese Morning Glory, for the attendants of the International Genetics Symposia. 120 persons visited the Institute.
Nov. 11. 53rd meeting of Misima Geneticists' Club.
Dec. 11. Three houses for official residences were completed.

29.
Sep. 11.

STAFF
Director
Hitoshi KIHARA, D. Sc.

1.

Members
Department of Morphological Genetics:
Yataro TAJIMA, D. Ag., Head of Department
Taro FUJII, Sadao SAKAMOTO, and Kimiharu ONIMARU

2.

Department of Cytological Genetics:
Yo TAKENAKA, D. Sc., Head of Department
Toshihide YOSHIDA, D. Sc., Assistant Head
Seizo TSUDA, Tsuguo TATEOKA, and Takaaki ISHIHARA

3.

Department of Physiological Genetics:
Hitoshi KlHARA, D. Sc., Head of Department
Hiko-Ichi OKA, D. Ag., Assistant Head
Motoo KIMURA, Ph. D., D. Sc.
Kiyoshi TSUCHIKAWA, and Toshifumi TAIRA

4.

Department of Biochemical Genetics:
Mitsuo TSUJITA, D. Ag., Head of Department
Yoshito OGAWA, D. M., Saburo NAWA, Bungo SAKAGUCHI, Toru ENDO, andTetsuo IINO (on leave of absence)5.

Department of Applied Genetics:
Kan-Ichi SAKAI, D. Ag., Head of Department
Kanji GOTOH, D. Ag.,
Yukio YAMADA, Akira MIYAZAWA, and Takatada KAWAHARA•
6.

Department of Genetics of Induced Mutation:
Seiji MATSUMURA, D. Ag., Head of Department
Tsutomu SUGAHARA, D. M., Assistant Head
Sohei KONDO

Part-time Staff and Research Associate
Kan OGUMA, D. Ag., Ex-Director, Emeritus Professor of Hokkaido Univ.
Yoshimaro TANAKA, D. Ag.

4

COUNCIL

Taku KOMAI, D. Sc.
Yoshinari KUWADA, D. Sc., Emeritus Prof. of Kyoto Univ.
Yosito SINOTO, D. Sc., Professor of International Christian Univ.
Sajiro MAKINO, D. Sc., Professor of Hokkaido Univ.
Hideo ETO, D. M., Assistant Professor of Tokyo Univ.
Kazuo FURUSATO,
Flora A. LILIENFELD, Ph. D.

Department of Administration
Kan-Ichi OTOFUJI, Head of Department
Sumiyoshi SUGIO, Head of General Affairs Section
Masao MIYAZAWA, Head of Finance Section
Naomi MATSUBARA, Hiroko NAKANO, and Junzo KADOWAKI
Clerks, Typists, Telephone operators, Chauffeur, Field laborers and Janitors.. ·24

Misima Branch of Hatano Tobacco Experiment Station
Masao TANAKA, Head
Flora A. LILIENFELD

Seiji IMAI
Assistants ... .4

Whole-Japan Association of Poultry Genetics
Hitoshi KIHARA, President
Kan-Ichi SAKAI, Vice-president

Association for Propagation of the Knowledge of Genetics
Hitoshi KIHARA, President
Yo TAKENAKA, Managing Director
Seiji MATSUMURA, Managing Director

COUNCIL
YO K. OKADA, Director of National Science Museum, Chairman
Seishi KAYA, Professor of Tokyo University, Vice·chairman
Masanori NAKAIZUMI, Emeritus Professor of Tokyo University
Bungo WADA, Professor of Tokyo University
Seizo KATSUNUMA, President of Nagoya University
Yohichi ASAMI, Emeritus Professor of Tokyo University
Toshitaro MORINAGA, Director of National Institute of Agricultural Sciences
Takeo IRIMANO, President of Japan Monopoly Corporation
Toshio SAITO, Governor of Sizuoka Prefecture
Yakichi NOGUCHI, Professor of Tokyo University
Riichi KAWAKAMI, Head of Department of Biometry, National Institute of Public
HealthKinichiro SAKAGUCHI, Professor of Tokyo University
Masatada TERADA, Professor of Jikei Medical College

RESEARCH PROGRAM FOR 1956

5

Takeo SAKATA, President of T. Sakata & Company, Yokohama
Ichiro ISHIKAWA, Commissioner of Atomic Energy Commission

RESEARCH PROGRAM FOR 1956
Department of Morphological Genetics
Studies on unstable genes in silkworm (TANAKA)
Linkage in silkworm (TANAKA)
Studies on the origin of wheat (KIHARA)
Studies on substitution of nucleus in wheat (KIHARA)
Studies on Agropyron (MATSUMURA & SAKAMOTO)
Nullisomic dwarfs among the offspring of pentaploid wheat hybrids (MATSUMURA)
Physiological genetics of the reaction of Japanese morning glory to day-length(SAKAMOTO)
Human genetic studies (KOMAI)

Department of Cytological Genetics
Cytology and genetics of tumors (YOSIDA & ISHIHARA)
Determination of sex and sex-chromosomes in animals (YOSIDA & ISHIHARA)
Cytogenetics with tissue culture method (YOSIDA)
Histology and cytology of testes of male tortoiseshell cats (ISHIHARA)
Determination and differentiation of sex in plants (TAKENAKA)
Induction of abnormal mitosis and inhibition of growth by substances extracted
from certain plants (TAKENAKA)
Interspecific hybridization in Nicotiana (TAKENAKA, FURUSATO & LILIENFELD)
Genetics of Pharbitis nil (TAKENAKA et al.)
Karyo·systematic studies in Poaceae (TATEOKA)

Department of Physiological Genetics
Studies on heterosis (KOMAI et al.)Problems on mouse genetics (KOMAI & TUTIKAWA)
Population genetics of some insect species (KOMAI & TAIRA)
Analysis of genes responsible for hybrid sterility and hybrid break-down in rice
(OKA)
Genetic studies of some physiological and agronomic characters in rice (OKA)
Theoretical studies of population genetics (KIMURA)

Department of Biochemical Genetics
Biochemical genetics of insects and microorganisms (TSUJITA, NAWA & SAKAGUCHI)
Embryological and biochemical studies of silkworm (TSUJITA & SAKAGUCHI)
Biochemical studies of some mutants in silkworm and Drosophila (NAWA & TAIRA)
Biochemistry of the mechanism underlying variations in flower colors in plants(ENDO & ABE)

6

FOREIGN VISITORS IN 1956

Biochemical studies on the mechanism of cell division in animals (OGAWA et al.)Biochemistry of the bitter substance in CitrulluB colosynthis (OGAWA et al.)Department of Applied Genetics
Breeding for high egg production in poultry (TANAKA, SAKAI & KAWAHARA)
Genetics of resistance to some diseases in poultry (KAWAHARA)
Genetic study of long-tailed fowl (TANAKA)
Experiments on the control of diapause in Antheraea pernyi (TANAKA)
Studies on polygenic inheritance (SAKAI et al.)Studies on competition between plants of different genetic constitutions (SAKAI etal.)
Population-genetic studies of "Red-Rice" growing among upland rice (SAKAI et al.)Studies on the technique of breeding in plants (SAKAI)
Genetic studies on "Cherry-red leaf" in tobacco plants (SAKAI et al.)Genetic studies on the migration activity in Drosophila (SAKAI et al.)Polyploidy and sterility in fruit plants (FURUSATO & MIYAZAWA)
Genetics of bitter-substance in Citrullus (FURUSATO)

Department of Genetics of Induced Mutation
Measurement of X- and r-ray dosage for induced mutations (KONDO)
Radiation genetics of wheat and barley (MATSUMURA & FUJII)
Relation between the quality of radiations and mutation (MATSUMURA, FUJII &KONDO)
Mutations induced by irradiation of tobacco plants (MATSUMURA & FUJII)
Radiation genetics and its practical application (KIHARA et al.)Studies on radiation-induced mutations in mice (SUGAHARA et al.)Studies on the physicochemical mechanisms of radiation effects on living organisms(SUGAHARA et al.)
X-ray diffraction studies on muscle (SUGAHARA et al.)Improvement of sugar beets by means of induced triploidy (MATSUMURA et al.)Research Students and Research Items
Chao-Hwa Hu (Overseas student from Taiwan Provincial College of Agriculture):
Cytogenetics of haploid rice and Nicotiana species
Yasuo OTA: Polyembryony in Citrus
Setsuji KATAOKA: Cytology of interspecific hybrids in Liliaceae
Shinya IYAMA: Introgression between the so-called Red-Rice and Japanese upland
rice varieties
Osamu YOSHIZAWA: Genetic studies of bacterial viruses
Kyozo WATANABE: Studies of nucleus in Paramecium
Yasuo SUZUKI: Population genetics of crop plants
Etsuo GOTOH: Population-genetic studies in Drosophila and domestic fowl
Hiroshi So: Karyological studies on the mechanism of growth-inhibition in cancer
cells
Keiko SATO: Genetics studies in animalsrFOREIGN VISITORS IN 1956

7

Yutaka ONO: Cytogenetics of domestic animals
Yuichiro HIRAIZUMI: Studies on polygenic inheritanceYoshiyuki AMANO: Effect of antibiotic substances on cell division
Kotoyo TSUCHIKAWA: Genetics of malformations in rat
Yoshihiko SUGIURA: Radiation genetics
Osamu KrrAGA WA: Population-genetics in Drosophila
Tetsuaki HASHIMOTO: Biological effects of radiation
Kenjiro FUJIOKA: Immunological-chemistry of organ-specific proteins
Shohachi SHIMOYAMA: Cytogenetics of flowering plants

FOREIGN VISITORS IN 1956
Apr. 28.

May

9.

June
Aug.

8.
4.
24.
27.

Sep.

1.
2.
4.
11.
12.

13.

14.

18.

Dr. T. H. SHEN, and Dr. Y. T. CHANG (Joint Committee for Rural
Reconstruction, China). Gave lecture on "Recent agricultural development in Taiwan".
Prof. C. M. POMERAT (Texas University, U.S.A.). Gave lecture on"Cytological abnormalities found in tissue-culture".
Dr. H. H. SMITH (Brookhaven National Laboratory, U.S.A.).
Dr. O. J. EIGSTI (Indiana University, U.S.A.). Gave lecture on "Present
status of seedless watermelon culture in the United States".
Prof. A. CHOVNICK (University of Connecticut, U.S.A.).
Prof. I. M. LERNER (University of California, U.S.A.). Gave lecture on"Population-genetic researches in the University of California".
Dr. C. C. LINDEGREN (Southern Illinois University, U.S.A.). Gave lectureon "Genetics of yeast".
Prof. J. F. CROW (University of Wisconsin, U.S.A.). Gave lecture on"Method of measuring mutation rate in human populations".
Prof. G. L. STEBBINS (University of California, U.S.A.). Gave lectureon "Mode of speciation in plants".
Foreign attendants of the International Genetics Symposia (about 110
persons).
Dr. H. W. LI (Taiwan Sugar Corporation, China). Gave lecture on"Interspecific and intergeneric hybrids in the plant-group related tosugar-cane ".
Dr. G. K. MANNA (Chittaranjan Cancer Hospital, India). Gave lectureon "Phylogenetic relationships among species of Hemiptera, fromcytological view-point".
Prof. R. E. COMSTOCK, and Prof. W. C. GREGORY (North Carolina
State College, U.S.A.). Gave lectures on "Statistical genetics ofquantitative characters" (from Sep. 14 to Sep. 17), and on "Radiation genetic experiments in peanuts".
Prof. B. C. JENKINS (University of Manitoba, Canada). Gave lecture on"The ROSNER Plan in the University of Manitoba".
Prof. E. R. SEARS (University of Missouri, U.S.A.). Gave lecture on

8

FOREIGN VISITORS IN 1956

20.
21.
28.
Oct.

3.

Dec. 28.

"Transmission of rust resistance from Aegilops umbellulata tocommon wheat".
Dr. R. F. KIMBALL (Oak Ridge National Laboratory, U.S.A.). Gavelecture on "Studies of mutations in Paramecium".
Prof. S. BENZER (Purdue University, U.S.A.). Gave lecture on "Basicunits of inheritance, from genetic studies in viruses".
Prof. A. MUNTZING (Lund University, Sweden). Gave lecture on"Polyploid breeding in Sweden" (at Sizuoka Agr. Exp. Sta.).
Prof. C. STERN (University of California, U.S.A.). Gave lecture on"Recent studies on mutation".
Prof. D. C. SMITH (University of Wisconsin, U.S.A.). Gave lecture on"Breeding of forage crops in the United States".

TRESEARCHES CARRIED OUT IN 1956
A.
1.

HUMAN GENETICS

Equilibrium of Human Genes(By Taku KOMAl)

The writer has studied the genetics of two rare human congenitalabnormalities, microcephaly and van del' Hoeve's syndrome which are due
to a recessive gene and a dominant gene respectively. These genes seemto persist in the population in an equilibrium state by an exact balance
between the new genes produced by mutation and the old genes eliminatedby selection. The rate of mutation has been estimated for both genes asof the order 10-5 • The incidence of the genes in population was calculated
as of the order 10- 3 for the gene for microcephaly and 10- 5 for the genefor van del' Hoeve's syndrome.
For the commoner congenital abnormalities such as hare-lip, congenital
dislocation of hip joints, congenital club-foot, anencephaly and hydrocephaly,
the incidence among new-borns is of the order 10- 4 -10- 3 • Our knowledgeof the genetics of these abnormalities is still insufficient, and it is probable that phenocopies are mingled among the cases of real genetic origin.
Hare-lip, for instance, is considered to be due to a dominant gene. If therate of mutation (u) of this gene is assumed to be 3 x 10- 5 and its selection
rate (s) 5 x 10- 2 , then the incidence of the gene (q) becomes q=u/s= 1/1667
and the incidence of cases 1.2/1000. The observed incidence of cases isabout 2/1000, so that the phenocopies may be about .8/1000.
For the still commoner genetic abnormalities such as taste blindness,color blindness, deficiency of palmaris longus muscle, malformation or deficiency of upper external incisors, the incidence is of the order 10- 2 • The
taste-blind people occur among Japanese in frequency about 6 per cent.
If 5 x 10- 4 is taken as the value of s for this gene and 3 x 10- 5 as that ofu, then q becomes 0.245 and the taste-blind people about 6 per cent. For
dominant characters of this class, if s is taken as 3 x 10- 3 and u as 3 x 10- 5 ,then the frequency of the abnormality becomes 2 per cent.
Lastly, it is very likely that there are cases where the equilibrium ofabnormal genes is maintained by heterosis, although few cases besides
that concerning sickle-cell anemia have been thoroughly worked out.

10

RESEARCHES CARRIED OUT IN 1956

2. Population Genetics of Albinism(By Katumi TANAKA)

Data on the distribution of albinos in the eastern region of Sizuoka-Prefecture were analyzed. The incidence of this abnormality was 10/126,000
in Simizu and 7/59,000 in Misima, which appeared to be higher than thefrequency found in the southern part of Gihu-Prefecture (16/762,500), andlower than that in Kasuga-village (5/4,000), as reported by Kurashima. It
may be inferred that the frequency of albinos, and therefore the frequencyof the albino gene, differs in various parts of Japan.
Of 28 albinos found in Simizu, Misima and adjacent regions, eight are
married; two of the matings are between albinos. This seems to suggest
a tendency to positive assortative mating.
The proportion of cousin marriages among the parents of albinos was
6/12; accordingly k=0.5. The frequency of the albino gene was estimated tobe 0.0042, by using Neel's formula under the assumption that the frequency of cousin marriages in the whole Japanese population is 6%.

3.

Variation in Taste-Response to "Citbittol"
among the People of Misima(By Yoshito OGAWA, T6ru ENDO, Yukihide ABE and Kenjiroo FUJIOKA)

Personal variation in taste sensitivity to the bitter substance containedin the fruit of Citrullus Colocynthis SCHRAD was studied in comparison
with that to P. T. C. The number of persons examined was 525. They
were all people residing in Misima.
Table 1.

Variation in the lowest concentration of "citbittol" solution
producing a bitter taste.

- _ .. _ ------------

Total
No.
1
1
1
1
1
of
128 256 512 1024 2048 persons

Concentration
Sex

Blind
Satupersons rated

1
2

-

1
4

1
8

1 1
16 32

1
64

--

-

-

-

Female
Male

4
4

3
2

2
2

2
2

1
4

4
9

8
9

25
65

65
86

67
44

Total

8

5

4

4

5

13 17

90

151

111

-

42
34

26
5

5
5

257
268

10

525

-----

76

31

T

11

RESEARCHES CARRIED OUT IN 1956

Variation in the lowest concentration of "Citbittol"* which gave a bitter taste is listed in Table 1.
Eight persons (1.52%) showed no response even to a saturated solutionof "Citbittol", and appeared to be blind to this bitter taste.
150

100

50

1

1

1

1

64

_1_,,-,_1_

128

256

512

1024

Fig. 1. Lowest concentration of "Citbittol" solution, effecting a bitter taste
among P. T. C. non-tasters (Blind) and tasters (Normal).

*

Refer to Report No. 36.

2048

12

RESEARCHES CARRIED OUT IN 1956

In order to find a relation, if any, between the taste-blindness to "Citbittol" and that to P. T. C., the examined persons were grouped into
two classes according to their reaction to P. T. C., positive or negative,
as shown in Fig. 1. The group blind to P. T. C. c~mprised 84 persons,
4 among them blind to" Citbittol". The other group, sensitive to P. T. C.,
was composed of 438 persons. Among them were the remaining 4 people
blind to "Citbittol". Though the percentage of Citbittol-blind people wasconsiderably larger in the first group than in the second, their number is
too small to allow for conclusions concerning the relation. Further studies
are needed.

B.

GENETICS AND CYTOLOGY OF MAMMALS,
BIRDS AND INSECTS
4. On the Origin of the Tortoiseshell Male Cat(By Taku KOMAI)

As has been mentioned in the previous numbers of this report, therecords of 65 specimens of tortoiseshell male cats indicate that such a cat
may be produced by a mother of any color, provided that her genotype
and her mate's genotype are in such relation that the gene for orange
color, 0, or its allele, 0+, may become heterozygous in her offspring.
Since 0 is sex-linked, the heterozygote should be a female in ordinary
cases. If a male would become heterozygous for this gene, the Y-chromosome would carry 0 or 0+. Such a male would be produced if crossing
over took place between the X and Y of the father, and transferred 0 or
0+ from X to Y. Next, to account for the sterility of tortoiseshell malecats, which is very usual, one seems to have to assume the presence in
the Y-chromosome of a gene complex for fertility of the male, and its
transfer to the X-chromosome by crossing over. Exceptionally there are
fertile tortoiseshell males, as recorded by some previous authors and also
demonstrated histologically by Ishihara in our Institute. The occurrenceof such males might be understood by assuming only the transfer of 0 or
0+ from X to Y without the reciprocal transfer of the gene complex for
fertility from Y to X. Or else, as has been suggested by Bamber andHerdman, such a fertile tortoiseshell male is a genotypical orange in which
the covering effect of the gene for orange is deficient and allows the blackcolor to appear to some extent.
Ishihara has studied the histology and cytology of six specimens of tor-

TRESEARCHES CARRIED OUT IN 1956

13

toiseshell males. Four of these had sterile testes, in which the spermatogenesis had been arrested in the spermatogonial or spermatocytic stage,
whereas two had testes which were apparently quite normal and fertile.

5.

Studies on the Mitotic Index in Various Organs of the Rat(By Takaaki ISHIHARA)

1)

Mitotic indices in various organs in the early stages of development.

It is well known that in higher animals mitotic activity in most tissues
gradually decreases with the development of the individual. The present
study deals with the mitotic indices of various organs of the rat (liver,kidney, lung, heart and cerebrum) in the early stages of growth. The
mitotic index in those organs was generally higher in the embryonic stage
than after birth, though at parturition some decrease occurred. The
mitotic index in organs of new born rats rapidly rose during four days
after parturition, the highest value being reached on the fourth day.
Subsequently, it began to decline and reached the bottom on the eighthday. Mitotic cells were hardly observed in 12 day old cerebrums and lungs,
or 30 day old kidneys and livers. It is interesting that the cerebrum
showed a somewhat different pattern from that of other organs.
2)

Relation between organ weight and. body weight.

The weights of various organs of the rat in the early stages of development, expressed as a percent of the weight of adult animals are set
out in Table 1. The table shows that each organ markedly increases its
weight in spite of a decrease in the number of mitotic cells. It may be
Table 1.

Weights of various organs of young rats as a percentof the weight of the same organs in adults.

=-------.= ===="=.=.===-~-~======'='==~=====;=======

OrgansDays after parturition

1

I

1 day

!10-d~;-1-15day;-1Liver

1_3~=2~_J

7.43%

Kidney

i

16.66

I

---1---- _1__

Adult rats
30 days1_°'_°_2_%_1__26_._7_2_%_1

7.1 gr.

21.66

1.2

1_ _

I

35.00

------~!-----------:------I-----I------_~eart__
L_un_g23_.__5_2

i! __I 12.18I

18_._4_6__

29_._4_1__ !_ _33_._8_2__ !

__1

2_1_.1_5__ 1_ _23_._84_ _ :__0__.6_8

_

1_.3

_

1

Cerebrum

48.28

66.66

I

72.32

!

1.65

14

RESEARCHES CARRIED OUT IN 1956

recognized, therefore, that the growth of organs depends not only upon
the increase in the number of cells but also on the increase in cell volume.
It may also be worthy of note that the weight of the brain remains
constant irrespective of the increase or decrease of body weight, while
the weights of liver, kidney and lung are proportional to body weight. It
may then be said that the brain has a developmental pattern somewhat
different from those of other organs.

6. Resistance to Blackhead Disease of Hybrid Chickens.
(By Takatada KAWAHARA)

Within-breed and between-breed matings were made using two males
and 24 females of White Leghorns (WL), and two males and 29 femalesof Barred Plymouth Rocks (BP). A total of 355 female chicks were hatTable 1.

Mortality from blackhead disease and other causes up to
the eighteenth week of chickens' life.
-_=-,-:=_.;:=",--====~===.:c:....----===-=--=

Experiment
No.

Matings- - , - , - , ' _.. _ - - - - - _ ..

TestedNo.

(%)

Death fromblackheaddisease (%)

BP~

BP¥x
WL~

Death due toother causes(%).. _ . _ - - -

_--_.

WL
BP
WL¥x
T1

Total
mortality- ~ - - _

40
29 .

10.0
10.3

0
0

10.0
10.3

50

2.0

0

2.0

19

5.3

0

5.3

69

10.1

0

10.1

69

2.9

0

2.9

79
54

46.8
35.2

43.0
31.5

3.8
3.7

46

8.7

8.7

0

38

15.8

10.6

5.2

133

42.1

38.3

3.8

84

11. 9

9.5

2.4

Pure

(~pL)
Hybrid(WL¥xBP~ )BP ¥xWL~.. , - - - - . , - - , - - ' - - - - - - - -_._------~-,--

WL
BP
WL¥x
BP~

T2

BP¥x
WL~

Pure
(WL\
BP )
Hybrid(WL¥xBP~)BP¥xWL~-"----,-._-RESAERCHES CARRIED OUT IN 1956

15

ched. The birds were maintained without any artificial culling up to theeighteenth week, except for cases of death spontaneously occurring during
this period. All of the dead birds were autopsied. The experiment was
conducted on the farm of Mr. Hara.
The total mortality of female chicks during the period of the first eighteen weeks of their life was determined as growing mortality; it isrepresented for the two breeds and the reciprocal F 1 hybrids in Table l.
A comparison of the growing total mortality of hybrid chicks with thatof the pure-bred chicks shows that the hybrids had a lower mortality.
While the difference of 7.2% in mortality in the first experiment (T1) is
statistically non-significant, the difference of 30.2% found in the second
experiment (T2) is significant at the 1% level.
The table shows also that a larger part of the difference in mortality
between the parental breeds and the F 1 hybrids in the second experiment
was due to blackhead disease. Mortality from this disease in pure breeds
in this case was as high as 38.3%, while it amounted only to 9.5% in F 1
hybrid chicks. The difference of 28.8% was also found to be statisticallyhighly significant at the 1% level.

7.

Quantitative Relationship between Autosomes and Sex Chromosomes
in a Few Related Species within the Coleopteran andHemipteran Groups of Insects(By Tosihide H. YOSIDA)

From comparative studies of chromosomes in some groups of Coleoptera
and Hemiptera, I have pointed out that a quantitative balance exists betweenA
the autosomes and the X-chromosomes, which can be expressed as T .

x(where T. A. and X are the total length of autosomes and X-chromosomes,
respectively). This ratio appears to be nearly constant, so far as different. WI'th'III a group are concerne.
d F or examp Ie, -T.A..
specIes
X III seven species of Coccinellidae (Coleoptera) was about 16. The same ratio in three
species of Rutelinae (Scarabeidae, Coleoptera) was about 24, and in ten
species of Pentatomidae (Hemiptera) about 12.
The relationship between autosomes and sex chromosomes was examinedin a few related species of Coreidae, Pentatomidae and Reduviidae (Hemiptera) to find out whether a similar relationship exists in cases in which a
multiple sex chromosome mechanism prevails. In these cases, the increaseof the number of autosomes is accompanied by an increase in the number

RESEARCHES CARRIED OUT IN 1956

16

of X-chromosomes. It may then be said that a quantitative balance between autosomes and X-chromosomes also exists in cases where multiple
sex chromosomes are involved.
Reference: YOSIDA, T. H. 1956. Studies on the chromosomes of Coleopteranand Hemipteran insects, with special regard to the quantitative relation between
autosomes and sex chromosomes. Proc. Tenth Intern. Congo Ent. (in press).

C.

CYTOLOGY AND GENETICS OF TUMORS

8.

Change of Chromosome Constitution in the Stem-lineof the Yoshida Sarcoma(By Tosihide H. YOSIDA)

In the course of a transplantation experiment of the YOSHIDA sarcoma, I
found tumor cells having a chromosome constitution different from thatusually observed in this sarcoma. As stated in the previous report (YoSIDA 1955)1), most of the cells of the original strain of the YOSHIDA sarcoma

Figs. 1-2. Photomicrographs of chromosomes in two strains of the YOSHIDA
sarcoma. 1) Original strain including two large V-shaped chromosomes.
2) Substrain containing two large V- and one large J-shaped chromosomes.
Arrows indicate the large V- and J-shaped chromosomes.
1)

Yosida, T. H. 1955. Proc. Jap. Acad. 31:

237-242.

RESEARCHES CARRIED OUT IN 1956

17

have 40 chromosomes, including two strikingly large V-elements (Fig. 1).
The new karyotype of the tumor cells also has 40 chromosomes, but three
are strikingly large, two of them V- and one }-shaped (Fig. 2). This
strain was found in the YOSHIDA sarcoma obtained from the Institute for
Infectious Diseases, Tokyo, and was kept in our laboratory for eleventransplant generations using W-strain rats. The W-strain rats had astrong resistance to this tumor in the first few transplant generations.
However, an increase in transplantability was found after several transTable 1.

Frequency of the original and the new karyotypes in
YOSHIDA sarcoma.
No. of cells observed

Transplant
generations

9th

10th

Strain of
rat used

2V type(Original type) I

WK

4413(30.2 %)

57

W

35

4(15.2%)

39

SH

21

6(28.5%)

27

CW

19

2(10.5%)

21

WK

25

7(28.0%)

32

W

30

3(10.0%)33

2( 4.8%)

43

CW

41
-

-

WK

51

W

23

11th

-

SH
CW

Total

I

-

70

I

39(30.2%)

159

I

8( 9.1%)96

II

4( 5.9%)

64

21

I

6(28.5,~)27

289(81.3)

I

57(19.7%)

-

I

-I

88

I
-

-

24

120

- - I--

1( 4.2%)WKW-

19(17.2%)-

9-11thTotal

2VlJ type(New type)

-

-

-

60

.-

i --

oo_.. _c

346

._ .-

_

plant generations. From the ninth to eleventh transplant generation it
was found that 81.3% of cells had the new karyotype, though the remaining 18.7% showed the original karyotype of YOSHIDA sarcoma. The newstrain was transplanted into three other strains. An interesting fact then

18

RESEARCHES CARRIED OUT IN 1956

observed was that different rat strains showed a different occurrence ofthe two karyotypes (Table 1). In W- and SH-strains, the frequency ofthe original-type cells was very low, while in WK- and CW- strains it wasvery high.

9.

Subtriploid Chromosome Constitution Characteristic of theTumor Stem-cells of Walker Carcinosarcoma of Rats
(By Tosihide H. YOSIDA)

From the karyological analysis of YOSHIDA-, MTK-II-, MTK-III- andHirosaki-sarcomas, it was found that the stem-cells of these tumors arecharacterized by a subdiploid chromosome constitution, induding a few
striking V- and/or J-shaped elements (Yosida 1955)1). On the other hand,
the TAKEDA sarcoma is characterized by tumor stem-cells with subtetra-

Fig. 1.

Chromosomes in a tumor cell of the WALKER carcinosarcoma.
Table 1.

Number of chromosomes in tumor cellsof the WALKER carcinosarcoma.

I 37

51

53 I 57
I--_._--~

Number of cells
observed__________ ~ . __ ~.,I

Number ofchromosomes.

i60' 61 I 62

__

1 I 1

1

L._.~

59

10

L

I
1 I 1

__ ..~. _1) YOSIDA, T. H. 1955. Proc. Jap. Acad. 31:

237-242.

63 I 98 j

1_

.
2

1

Total

20

RESEARCHES CARRIED OUT IN 1956

19

ploid chromosome constitutions, having several distinct V- and J-elements(YOSIDA 1952)1).
Unlike these two cases, the tumor stem-cells of the WALKER carcinosarcoma are characterized by subtriploid chromosome constitutions. The
numerical variation of chromosomes in this tumor is shown in Table l.
The table shows that cells with 60 chromosomes were most frequently
found, while the chromosome constitution was very complicated. Of the
60 chromosomes, 26 were rod-shaped, 12 J-shaped and the remaining 22lUOOUDU~UVVVUV«VVOOU
II u •• V

U(( nee 11 vIllv ~~ II~~ {( It ~ ,t " 't )t 'C " " )\ ')")1 )c )l ")C U Ie

Fig. 2. Serial alignment of chromosomes in the cell shown in Fig. 1.
V-shaped. A large V-chromosome was very conspicuous as shown in Figs.
1 and 2. Such a chromosome assortment seems to be characteristic of thestem-line of this tumor.

10. Occurrence of Distinct V-Chromosomes in Cells
of Seven Original Rat Hepatomas(By Tosihide H. YOSIDA and Takaaki ISHIHARA),

In the course of experiments carried out in order to induce a hepatoma
in white rats by administration of D. A. B. (p-dimethylaminoazobenzene),we (YoSIDA and ISHIHARA 1956)2) have found one consisting of four tumorous masses. From a karyological analysis, it was found that only oneof them was characterized by the presence of a distinctly V-shaped chromosome. We continued the experiments and succeeded in inducing six otherhepatomas in rats five months after the administration of D. A. Boo The
results of our observations of those original hepatomas are as follows:
1) YOSIDA. T. H. 1952. Gann. 45: 9-15.
2) YOSIDA, T. H. and T. ISHIHARA 1956.
6: 22-23.

Ann. Rep. Nat. Inst Genet. Jap. No.

RESEARCHES CARRIED OUT IN 1956

20

In two hepatomas, designated as WK-2b and WK-1b, no V-chromosome
was found in the tumor cells (Table 1). On the other hand, the other
Table 1. Chromosome constitution of tumor cells
in the seven original hepatomas.
=-----==-.-.=---------

Strain ofhepatoma

No. of cells
observed
32

H-2c
---

I

Variation in numberof chromosomes

No. ofV-chromo
per cellNo. ofcells with
V's

range

mode

37-88

43

2

1/32

34

1

13/15

---------

----

H-2a

15

28-61

20

25-151------

H-4,· { II

28-78

37

0
41

9/37

---------

III16

34-168
-

WK-2b

15

81

0

--------

30-44

42

0
----

H-lb

18

33-84

42

--._--------------

W-l

6

54-66

WK-lb

10

37-86

1

3/18

------------

46

4/6
0

* Description has been given in the Annual Report of this Institute, No. 6(1956).

four hepatomas (viz. H-2c, H-2a, H-1b and W-1) were characterized by thepresence of cells with one large V-element. Two (H-2a and W-1) had aremarkably high frequency of cells with one V, while in the other two(H-2c and H-1b) their frequency was low. V-chromosomes were not foundin rats which received food containing azo dye and showed no sign ofmalignant growth. It should be mentioned that the V-chromosomes were
never found in normal cells and that though they are characteristic oftumor cells, they are not necessarily found in all cases.
The present study was undertaken with regard to the occurrence of theV-elements. But it was incidentally observed that also other small changes
took place in the chromosome constitution of the hepatoma cells. These
are now being investigated in our laboratory.

,RESEARCHES CARRIED OUT IN 1956

11.

21

A Study on the Transplantability of the WPY-Rat Sarcoma(By Takaaki ISHIHARA and Tosihide H. YOSIDA)

The WPY-rat sarcoma is a kind of fibrosarcoma which developed in astrain of rat, WAYNE pink-eyed yellow (WPY-rat), in our laboratory. In
transplantation experiments of this tumor, it was found that transplantation was successful in all WPY-rats, but not in the Wistar-King-A strain(WK) (Table 1.). Transplantation was also successful in all F 1 hybrids
Table 1.

Transplantability of WPY-rat sarcoma to WPY,
WK-strains, F 1 and F 2 •~~=~~-=====-=-===~---

Result of transplantation
StrainPositiveI

No. of ratstransplantedr---fug~tive\ % of positivetransplantation_I---'--------------------'--------'-------

WPYl)
WK2)
I
F 1 (WPYxWK)I
F 2 (WPY xWK)
Remarks.

126

o

126

100

o

30

30
3

o

30
30

100

66

69

1) WAYNE pink eyed-yellow.

2)

o
4.34

Wistar-King-A.

between the two strains (WPY xWK). It may be assumed that some Hgenes (Histocompatibility genes) are responsible for the observed transplantability, as in mouse tumors. To determine the number of the Hgenes, the variation in transplantability in the F 2 generation was examined.
The genetic experiment showed that 4.34 percent of F 2 -animals weresusceptible to the tumor, suggesting the possible number of H-genes tobe about ten which are effective if each is represented at least by one
dominant allele.

12.

Effect of Kinetin upon Division of " YOSHIDA-SarCOma Cells"(By Yoshito OGAWA, Yukihide ABE and Kenjiroo FUJIOKA)

Kinetin (6-furfurylaminopurine) was isolated by Miller et al. (1955, 1956)
from DNA of herring sperms. They found that it induced a high rate ofcell multiplication in the callus tissues of plants_ Guttman's study (1956)
has shown that in onion root tip cells kinetin promoted mitotic divisions
and induced polyploidy besides various forms of pycnosis. However, its
effect upon the division of animal cells is not well known, though negativeRESEARCHES CARRIED OUT IN 1956

22

results have been reported by Lettre (1956) who used animal and humancells.
We have investigated the effect of Kinetin upon the mitotic activity of
YOSHlDA sarcoma cells transplanted to a strain of rat, Wister. When thesolution of kinetin was injected into the abdomen, a significant increasein the frequency of mitotic figures was found in the tumor cells after
about 120 hours (significant at the 1% level as shown in Tables 1 and 2).

Table 1.

Frequency of mitotic figures after injection of kinetin
Kinetin (mg)

Hours

Control

0.15

0.03

0.75

·Propor- A I * Propor- A I * Propor- A I * )'ropor- Angle*
tion
ng e
tion
ng e
tion
ng e , tion

1~5.31% l3.32l-3~09-%

1O~i2 !3~65%

4.77

12.62

9.55

4.33

12.01

2.56%
2.88
2.80

9.21
9.77
9.63

---------6-.25%
48

120

3.51

10.78

2.75

3.51

11.01
10.80

2.73%
2.14

9.51
8.41

I

2.39%
2.47

8.82, 4.12%
9.041 3.88

11.73
11.36

* Degrees after arc-sine transformation of percentage. Host: rat (wister);
2 months old. Preparation: aceto-orcein squash technique. The percentage
of dividing cells was determined by observation of 10.000 cells. No dividing
cell was found in the ascites if kinetin only was injected and the sarcoma
was not transplanted.

Table 2.

Variance analysis of the frequency of dividing cells

SourceDegrees of
freedom

48 hrs.
Mean sq.

120 hrs.
Mean sq.

Treatment
Error

3
5

4.66
1.52

3.99**
0.1**

Significant at 1 % level.

However, it was found that kinetin did not change the relative frequency
of different stages of mitosis.
In the control-experiment, as shown in Fig. 1, the frequency of metapha-

23

RESEARCHES CARRIED OUT IN 1956

sic cells showed two phases of increase, two and ten days after the transplantation of YOSHIDA sarcoma. In the treated rats, the second phase was

150

100

Cont.
0.15~r

O.O.3mg50

o. 75m~10

15

Fig. 1. Daily change of frequency of metaphasic cells (pathological figures
excluded) after injecting kinetin into the abdomen of rat, 10.000 cells being
observed per day. Abscisse: Days after transplantation. Ordinate: Number of metaphasic cells observed.

not apparent, probably because the animals were starved during the firstincreasing period, which lasted longer than in the non-treated animals.
The frequency curves for treated rats, not showing any tendency to abruptchange, seem to suggest that kinetin may act upon mitotic activity directly, the effect not being due to some secondary metabolite. Thus wefind a case in which kinetin acts on animal cells as on plant cells.

D.

GENETICS AND BIOCHEMISTRY OF THE SILKWORM
AND OTHER INSECTS
13.

Genetics of the Silkworm(By Yoshimaro TANAKA)

1) Linkage Tests.
Hereditary relationships were tested between Se (White-sided egg) andseveral other genes such as st (stony), ge (geometrid), nb (narrow breast)

24

RESEARCHES CARRIED OUT IN 1956

and so (sooty). They were all inherited independently, no linkage being
observed. This experiment was carried out under a grant-in-aid of the
Ministry of Education.
2) Inheritance of "Light Eye-spot".
"Light eye-spot" is a strain with otherwise normal marking but its eyespot is markedly lighter in comparison with the "lunules" and "stars".
It was crossed with a standard normal type (race p 22), and the author
found that this character was allelic and a simple recessive to normal +p.
The range of variability in density of the eye-spot in F 2 was somewhat
greater than the total range in parents. "Light eye·spot" may be designated by the symbol pIe.
3) Selection in No-lunule.
In the strain of Nl (No-lunule), some larvae are provided with small
rudiments of lunules while others are entirely free from lunular marking
on the second abdominal segment, though these two types are somewhat
overlapping. These different forms were observed mixed among full sibs.
The author tried to fix a strain with no trace of lunules on one hand, anda strain with rudimentary lunules on the other hand by selection.
After several generations, both positive and negative selections proved
effective, the females from both strains giving rise to different ratios of"complete Nl" and" incomplete Nl" offspring.

14. Effect of Day-length during the Embryonal Stage of a Wild
Silkworm, Antheraea pernyi, on the Pupal Diapause(By Y oshimaro TANAKA)

Since 1937, the author accumulated experimental data showing that along day during the larval life inclines pupae to diapause, while a short
day makes them develop into moths without hibernating.
On the contrary, the photoperiodic effects on embryos were divergent,often even contradictory. One of the disturbing causes seemed to theauthor to be the influence of day length during the larval life. To lessen
this influence to a minimum, he made a design of experiment to rear larvae under "neutral" day length of 14 or 15 hours a day, after exposing
the eggs to different day lengths.
By this way, he could disclose that photoperiodic effects upon embryos
are just opposite to those upon larvae, i.e. long day predisposes to diapause, and the short day to imaginal development.

..

RESEARCHES CARRIED OUT IN 1956

25

15. Effect of Cytoplasm upon the Expression of Quantitative
Characters in the Silkworm(By Yataro TAZIMA, Eiichi MlDORIKAWA* and Mieko SHIOKAWA*)t

In order to determine the effect of the cytoplasm upon the expressionof quantitative characters, reciprocal crosses were carried out with regard
to the weight of cocoons and of cocoon-shells.
The method adopted in this investigation was as follows. Females ofstrain A were crossed to males of another strain B, and this was followedby back-crossing the B male repeatedly in subsequent generations, i.e.
AxB, (AxB)xB, {(AxB)xB}xB, ---etc.. Special attention was paid tomating the same male of B strain to females in each of the back-crosses.
About 16 pairs of such crosses were performed in each generation. The
heterotic vigour with reference to cocoon weight and to some other characters in F 1 and in the subsequent back-cross generations decreasedslightly generation after generation. Crosses were then made to an unrelated strain. In order to test whether the decrease in the expressionof characters occurred with the increase of the number of back-crosses or
was dependent upon the direction of the cross, all the crosses were raisedin the same season. Special care was taken to mate the same male tothe females of each generation in order to avoid disturbances, caused bydiverse genic constitutions of the male parents. About 16 lots of the samecross of each generation were mixed together and all crosses were raised
simultaneously in the same season.
The results obtained in the autumn of 1956 are shown in Table 1.
Here F and F m are Japanese type fixed hybrid breeds between Japaneseand European silkworms, while 75 and 90 are Chinese type fixed breeds
from hybrids between Chinese and European silkworms.
It is evident from Table 1 that 1) when a cross is made to an unrelated
strain, heterotic vigour appears again irrespective of the number of backcrosses carried out before, the performance of the Fl's being scarcely different from each other, and that 2) a marked difference is observed between
both types of reciprocal crosses, independently of the number of backcrosses. Performances of the offspring when the female parents wereJapanese were superior to those when they were Chinese. Similar results were also obtained in other experiments, carried out in the summerof the same year. These results agree with that of SHIMIZU (1947). He
reported that in most cases Japanese type as the female parent gave offspring superior to those from Chinese type females so far as cocoon weightis concerned.
* The Silk Science Research Institute, Tokyo.

RESEARCHES CARRIED OUT IN 1956

26
Table 1.

Comparison of cocoon weight and cocoon-shell weight inreciprocal crosses.

1-

Cocoon wt.

i

Cross

~---

--~

-----

Cocoon-shell wt.

(F1Fml) X90--r--

2201~1g±±~142. 06* ----159±~- 4-2-~f-±-2.-8--'--- -~O.O·~;-.O----(F1Fm2 ) X90(F1F m3)x90(FIFm5) X90

203±15.2201± 12.8I

159± 12.5
157±13.7159± 13.2

43.3±3.1
42.1±2.842.8±2.8

39.6±3.639.1±3.3
39.6±3.4----+---- _ . _ - - - - - - - - - -I

90 x (F1Fml)
90 x (FIF m 2)
90 x (F1F m3)

179±12.9185±12.0
190±13.0

90 ~FIF m _)1=~±22._5_1_.~9±10.5

39.3±2.940.4±3.1
41.3±2.840.4±3.2(90.751 ) xF m
(90.75 2 ) x F m(90.75 3) xF m
(90.75 5 ) XF m

197±13.9198±13.7
194±12.4
194±13.1

155±12.7
157±11.3
152±11.2
152±10.440.7±3.340.9±3.1
41.1±3.040.9±2.937.9±3.0
37.8±3.1
38.0±2.737.6±3.2

F m x (90.75 1)
F m x (90.75 2)
F ill x (90.75 3)
F m x (90.75 5)

211±13.6214±16.0
210±15.0
206±13.8162±12.0160±14.5162±12.9157±11.042.6±3.944.2±3.5
4L9±3.442.3±3.1

41.0±2.939.1±3.538.1±3.1
37.6±3.45I

144±1O.9148±1O.5150±12.0

37.2±3.337.2±3.1
38.8±3.0
38.7±2.8-------,-----_._._-----* Standard Error
Thus it may be taken as proved that dissimilar results are obtained inthis insect, depending on the direction of the reciprocal crosses. Differences could be clearly observed in the case of characters that manifest
themselves early in the life history of the silkworm, as hatchability, viability of younger instars etc. (KIKKAWA 1942, TAZIMA et al. 1955). It isnoteworthy that even in such late traits as cocoon weight and cocoonshell weight the maternal effect is observable.
Between the two types of reciprocal crosses chromosomal differences
should be limited only to the sex chromosomes. In this respect, the males
derived from the two types of crosses do not differ genetically, having
two Z chromosomes, one from the mother and the other from the father.
Females might be different depending on the type of the cross since they
have only one Z chromosome. Therefore, differences should be restricted
to the females only.
When cocoon weight of the male for each type of reciprocal crosses is"f

RESEARCHES CARRIED OUT IN 1956

27

compared, the difference between both types is obscure in some cases,
but not so in others. This seems to mean that environment favors one
type of reciprocal cross owing to the difference in the cytoplasmic constituents until fairly late stages of the development.
From the above we are led to believe that the causes for differences
between the reciprocal matings are probably not nuclear but cytoplasmic.
This suggests that the cytoplasm may function in the zygote as an activating background for the expression of the nuclear genes.

16. Studies on the Complex Nl-U-Di Loci in the Silkworm(By Mitsuo TSUJITA)

1) Nl 2 locus.

"

The Nl 2 mutant, produced by X-ray treatment, lacks crescent patterns(semi-lunar patterns), and resembles Nil which exhibits what is known as
non-lunar patterns Nl. Larvae with the genotype +/Nll , however, often
have rudimentary crescent and star-shaped patterns, which become a little
more distinct after sib-mating. This phenomenon can be explained byassuming the presence of modifiers of Nil. On the contrary, the larvae
with the Nl 2 marker lack completely the lunar patterns but have normal
star-shaped patterns. The Nl 2 mutant had been classified at first as theENe strain, because of its phenotype, and kept several generations. But
the following experimental results of our genetical analysis have provedthat this judgment was not correct.
( i) Individual F 1 hybrids between Nl 2 and U or Di were crossed tonormal or Di. From these crosses no recombinants could be obtained.
(ii) In the experiments using the original Nl 2 strain, some abnormal
segregation occurs. Besides, individuals homozygous for this gene areable to survive. These phenomena seem to be due to a chromosomal
aberration. Individuals from which the chromosomal abnormality wasremoved, showed almost the same genetic behaviour as Nil, although theirphenotypic appearance was somewhat different. Needless to say, the genesymbol Nl 2 designates this genetic unit.
2) Abnormal segregation of the original Nl 2* strain.
From the cross of +/+ x +/Nl2 , normal and Nl 2* larvae segregated almost in the ratio 1: 1 (sometimes the number of the latter was a little
larger than that of the former). After sib-mating the +/Nl2* individuals,
Nl 2* and normal segregated approximately in the ratio 3: 1.

* Means that chromosome XIV has some aberration.

RESEARCHES CARRIED OUT IN 1956

28

From the cross Nt 2 */Ux +/+ or +/+ x Nt 2 */U, a 1: 1 ratio in thenumber of Nt 2* and U was found as expected. It was further found from'Ii

Nl~ oa

0

oa/oa

~

X

I

-I

oa/oa

fix

Nl,JoaNl.*loa

GI 0

-

fix

e
X

I

Ctxe
,.--I-,

Nl./oa

oa/oa

0
0

~

~

0

I

0

X

Ci)

I

i

CIt 0

Original Nt: larvae wh4ch have a chromosomal aberration

+

~

I

Nl 2
Nt, larvae without the chromosomal aberration

such

e

.. {

~

such ase0

as-+-1------------Nl 2

oa larvae with transparent hypodermis

the results of sib-mating individuals with the genotype Nt2 */U that individuals homozygous for Nt 2* are viable. This segregation suggests that
this original Nt 2* strain is somewhat different from the known Nt l strain
in its genetic behaviour. The following finding suggests that the larvaeof this strain have an aberration involving chromosome XIV.
From the cross +/Nt 2* x oa/oa, normal and two types of Nt 2 larvae arise,
the first with a transparent hypodermis and the second with a non-

RESEARCHES CARRIED OUT IN 1956

29

transparent hypodermis. Although the segregation ratio of the threephenotypes is not always the same, in some of the batches it is almost
1: 1: 1.
The fact that the special chromosomal aberration had been kept throughseveral generations after the finding of this mutant and the abnormal segregation ratio mentioned above suggest that the chromosomal aberration
occurs on chromosome XIV itself.
The larvae which have a transparent hypodermis showed almost thesame genetic behaviour as Ntl, namely from the cross oafNt 2 x oa/oa orfrom its reciprocal. Oily larvae and oily Nt2 larvae segregated in theratio 1: 1. In the sib-mating of oafNt 2 , all of the embryos homozygous
for Nt2 die in an early developmental stage.
The following diagram summarizes the results obtained from crosses
starting with the original Nt2*.
Several hypotheses can be considered as explanations of the abnormal
segregation of the original Nt 2 strain. Among them the following ishighly plausible. In the original Nt2 individuals there is an unstable attachment of a small chromosomal fragment on which the normal genetic
unit for Nt2 is located. Therefore, from this strain two types of Nt 2 segregated, i.e. individuals having chromosome XIV with or without its fragment. The strain from which the fragment once was lost produces only
one type of larvae which behaves normally.
3) Linkage relation between U and oa.
The question of whether crossing-over between the oa and U genetic
units occurs was examined and the following experimental results wereobtained.
From the cross oaf Ux oa/oa, oily and U segregated. From the reciprocal cross a very small number of normal larvae appeared in addition tothe oa and U individuals. The results of several repeated experiments
which were carried out during the years 1955-'56 are given in the following table.
, The single oily larvae of composition o(l_l! (?) had side markings whichoa +resembled those of larvae with the gene constitution U/+; PiP. Larvae
resulting from the cross between this type and oa/oa, however, were alloily and did not show this character. From the cross between the normals in the above table and oa/oa, oily and normal are produced in theratio 1: 1. Therefore, it is certain that normals are produced from thecross oa/oa x oaf U. So far as our experimental results went, we could not
obtain larvae with the genotype oaU/oa+. If it were true that only one
type of recombinants can be produced from this cross, there is a possibility of an unusual crossing over.

RESEARCHES CARRIED OUT IN 1956

30

Table l.

Segregation from the cross aa/aa x aa/U.

No.

aa/aa

U/+

aa U
aa U

aa +

1
2
3
4
5
6
7
8
9
10
11
Total

175
65
139
159

141
88
92
166

0
0
0
0

0
0
0
0

316
153
231
325

0
0
0
0

210
158
252
70
87
214
1529

115
188
242
74
32
148
1286

0
0
0
0
0
0
0

1
1
0
0
0
0
2

326
347
494
144

0.3
0.3
0
0
0
0
0.6

-

+ +

I

Total

119
362
2817

I

Recom. Value

4) Di region.
The present experimental results seem to show that Di, U, Nt b Nt2
and Di form a pseudoallelic series. The crossing-over value between odk
and U is 8.0 (Hasimoto '41), and that between odk and Di 12.9 (Chikushi'55). According to these experimental results, some distance on the chromosome should be considered to exist between U and Di. UB', whichcauses a dark brownish color of the larval body, has been proved to beallelic to U (Tsujita '47). Furthermore we could obtain a mutant n which
is similar to Di. Namely, like Di, larvae homozygous for n completely
lack crescent and star-shaped patterns, and have almost the same bodycolor as the normals. Consequently, it can be said that they have theappearance of an extremely diluted form of Di. The F 1 larvae from thecross between Di and n showed the characteristics of Di, and in the F 2 ,two types, Di and n segregated. The gene symbol Dio was given for Di
and Did for n.
From the cross Did/Diox Did/Did and its reciprocal, Dio and Did segregated. In the reciprocal cross a very small number of normals were produced. From a preliminary experiment it is inferred that the phenotype
Did-Dio. IS. C1ear f rom t h'ISof - exh'b'
I Its norma I appearance. A t any rate, It+ +experimental result that Did and Dio form a complex locus.
5) Complex Nl-U-Di loci.
Several genes U, UB', Nt b Nt 2 , Dio, Did and oa, most of which giveRESEARCHES CARRIED OUT IN 1956

31

similar effects, form a pseudoallelic series, and they occupy a certain
length of the chromosome XIV. As in multiple alleles, recombinantscannot be obtained from the crosses among them except in very rarecases. Their function is related to morphogenesis in an early developmental stage and some of them exhibit complete or partial recessive lethal
action.
It has been known that terminal fusion between chromosomes VI and
XIV occurs under natural conditions (Itikawa '52). This fact shows some
intimate relation between these chromosomes. Both E and Nl-U-Di pseudoallelic genes which are located on each of the two chromosomes VI,
XIV, resemble one another and give similar phenotypic effects. There may
be some relation between these two gene series. However, we can not say
anything certain without further investigation on this point.

17. Genetical and Biochemical Studies on the Yellow Lethal Silkworm
VI. Chitin Production and Melanin Metabolism(By Mitsuo TSUJITA and Bungo SAKAGUCHI)'

1) Chitin:-In the yellow lethal larvae, the cuticular layer of the hypodermis, especially that of the mandible, does not develop properly, so thatthey cannot chew mulberry leaves and starve to death. As the amountof chitin contained in the cuticular layer of the larval hypodermis may be
regarded as indicator of hardening of the cuticular layer, measurementsof the amount of chitin contained in normal and mutant larvae were carried out by FRAENKEL'S method (1947). The experimental results are given
in Table 1.
Table 1.

-~t~ai:sI

Amount of chitin·IP£ho~~~g~: f66~c

D;y wei¥ht ofI
hypodermIS (mg) in 5% KOH (mg) i--+-"--I-~O---

lern l77.5% of Chitin

,

,

14.01

8.01

14.6
11.3

------ ._-----'---------'---------As shown in this table the production of chitin in the yellow lethal larvae is much smaller than in the normal larvae.
2) Phenolase and phenol substances:-By using a WARBURG manometer,
the phenol oxidase activity of the epidermal tissue in the larvae was measured directly after the 1st moulting of + and lem 1 larvae. The following table shows the experimental results.

32

RESEARCHES CARRIED OUT IN 1956
Table 2.
~------_._-----~.

Strains

Phenol oxidase activity-

Tyrosinase
I
Dopa oxidase- 02 uptake-------Relative--' -O;-iiptak~-Relative--mm 3/hour
activity
mm3 jhourI
activity---~-·~--_·~--·~-I-----I

+

37.8
32.5

lem 1

100.0
86.0

107.5
75.3

I

~

100.0
70.0

A weak activity of tyrosinase was detected in the mutant larvae andthe dopa oxidase activity in the normals was much stronger than in thelem 1 larvae.
Paper chromatography was used for the separation of phenolic substances and their nature was examined by the Diazo reaction and bysome other methods. The experimental results obtained are given in thefollowing table.
Table 3.

Detection of phenolic substances in larval hypodermis---==---~~--!---~rosine

Strains0.45*==="-----

I

Dopa
0.3*

-----------

+

±
±

lem 1

----

+

I

Unknown substances
0.1*

+
+

(developing sol vent: 4 Butanol:
1 acetic acid: 1 H20)----- - - - -* Rf. value

Tyrosine and dopa substances could not be detected in the normals but
in the yellow lethal larvae a trace of tyrosine and a large amount of
dopa could be found.
The experimental results of Table 1 and 2 suggest that in the mutant
larvae a slight block exists at the step of tyrosine --i>- dopa and a considerable block at the step dopa --i>- x substance in the sequential reactions of melanin formation.

18. Genetical and Biochemical Studies on the Metabolism of
Pteridines in Insects(By SaburQ NAWA, Bungo SAKAGUCHI and Toshifumi TAIRA)

In regard to the mechanism of pterin metabolism in insects such as.
Drosophila and silkworm, the following scheme has been considered by
the authors:

RESEARCHES CARRIED OUT IN 1956

33

Xanthopterin-B - 2-amino-4-hydroxypteridine-6-carboxylic acid~ 2-amino-4-hydroxypteridine (AHP) ~ Isoxanthopterin.
These pterin compounds in the eye-color mutants of Drosophila are closely related to the formation of red pigment in eyes. Futhermore, it has
been shown from genetical and biochemical studies that the gene lemon
lethal (tem l ) in silkworm works in close relation to the metabolism ofthese substances.
LOWRY et al. (1949) have reported that xanthine oxidase-preparations fromthe milk of mammals were capable of catalyzing the reaction designatedas A in the scheme. In both Drosophila and silkworm, an enzyme oxidizing AHP to isoxanthopterin was found and its nature investigated.
The enzyme in the silkworm was found during its whole life-cycle fromegg to adult. Since a large number of silkworm eggs were available,
they were used as the material for this experiment. Eggs of a normal
strain of silkworm were homogenized with 0.1 M phosphate buffer at pH
7.5, and the preparation was centrifuged. The supernatant solution was
adjusted to 0.6 saturation with ammonium sulfate. The precipitate obtained from the centrifugation was dissolved in phosphate buffer. Afterincubating the enzyme solution at 37° for 4 hours with crude trypsin, thedigestion mixture was dialyzed with running water for 2 days. The dialyzed fluid was reprecipitated by 0.45 saturation with ammonium sulfate.
The centrifuged precipitate was dissolved in water, and the unsolved material was removed. The enzyme solution obtained by the above procedure loses as much as about 30 to 40 per cent of its activity after being
kept at 5° for 24 hours. The enzymatic oxidation of AHP to isoxanthopterin (reaction A) was measured by the increase of optical density at 335
mil, while that of xanthine to uric acid (reaction B) was measured at
290 mil. This enzyme can catalyze both of the reactions A and B shownin the above scheme.
In reactions A and B, the aerobic activity of the enzyme was only afew per cent of what it was in the presence of methylene blue. Since
the enzyme found in silkworm is not autoxidizable, it must be fundamentally different from the xanthine oxidase found in milk or in mammaliantissues, which is autoxidizable. Westerfeld et al (1955) have reported thatthe xanthine dehydrogenase found in bird tissues, such as chicken liver,
was not autoxidizable to any significant extent. Thus, the enzymes from
insects and birds appear to be similar.
To measure the relative ratio of reaction velocity under the optimal
condition for each substrate, the pH optima were determined (Fig. 1).
Using milk oxidase, the pH optima with AHP and xanthine as the substrate were in the neighborhood of 5.5 and 8.5, respectively. The maxi-

RESEARCHES CARRIED OUT IN 1956

34

mal rate of xanthine oxidation for milk enzyme was about 5 tImes ashigh as that of AHP oxidation, while silkworm enzyme oxidized AHP at

B

T

6.5

7.0

8,0

8,S

9,0

lOD

----7

rH

Fig. 1. The pH optima with AHP (A) or xanthine (B) as substrate in thepresence of methylene blue.

approximately the same rate as that of xanthine oxidation in the presenceof methylene blue. These results support the hypothesis that pterins
found in insects have a more important function than those in mammals.
In Drosophila, the eye-color mutants seem to have different enzymatic
activities, although the relation between the enzyme and other substances
has to be further considered. For example, the experimental results forthe enzyme, obtained from the supernatant of homogenized prepupae ofbw, sed, and wild type strains in Drosophila, were as follows. The participation of methylene blue in the reaction increases the oxidative velocity
in both reactions A and B. The crude enzyme preparation from wild typeor bw strain catalyzed the reaction to some extent even if methylene blue
was absent, while that from sed strain did not. This may be because thesed strain has little electron acceptor in vivo. So far as we know, the sed
strain has a large quantity of xanthopterin-B in its testis, and also hassome other special properties in regard to pterins.

RESEARCHES CARRIED OUT IN 1956

35

This evidence suggests that there may be a close relationship between
the metabolism of pterins and that of purines. Thus, the mutants lemon(tem) and lem l in silkworm have a large quantity of xanthopterin-B inlarval epidermis, and the strain homozygous for lem l comes to death because it cannot eat mulberry leaves at first molting stage. The phenomena mentioned above will be better understood through further studiesof the metabolism relating to purines and pterins.

19. Microdetermination of Uric Acid in Drosophila melanogaster
during Metamorphosis(By Toshifumi TAIRA and Saburo NAWA)

It has been assumed that the red eye pigment of Drosophila melanogaster could be traced back to pteridine derivatives (by Heyman et aI, Hadorn
et aI, Forrest and Mitchell, Viscontini et aI, and also the present authors), and that pterin may come from the conversion of uric acid (byForrest and Mitchell).
The writers have been engaged in the study of the relationship between
pigment formation and pterin metabolism on the basis of this hypothesis.
During this year, microdetermination of uric acid in eye-color mutants of
Drosophila melanogaster was conducted by the spectrophotometric method
using uricase.
Fifty individuals, from larval to adult stage, of eye-color mutants, namely Oregon-2, v, bw, se, sed and lV, were used as materials. After homogenizing the materials in a solution of glycine buffer (pH 9.4), the solution was boiled on a water-bath for five minutes at lOOoe, and then centrifuged at 4,000 r.p.m. for two minutes. 0.5 m!. of the supernatant was
mixed with 4.5 m!. of the uricase solution, which was obtained by dissolving 4 mg uricase crystalline in 100 m!. of glycine buffer.
The test solution was examined spectro-photometrically at the wave
length of 292 m,u, and it was incubated for four hours at 37°e. Then the
optical density was measured again by the same method. The quantityof uric acid was computed from the values of 6E thus obtained. The
results are shown in Table l.
The data in Table 1 suggest that (a) the quantity of uric acid in various
mutants reaches the maximum at the stage of postpupae, (b) the modeof increase and decrease in quantity of uric acid in both bw and w strains,which have only a small amount of pterin compounds, is similar to thatfound in other strains having many pterin derivatives, and (c) there is no
direct metabolic relation between uric acid and pterin.

36

RESEARCHES CARRIED OUT IN 1956
Table 1.

Strains

Quantitative change of uric acid in eye-color mutants duringmetamorphosis (rlmg).

Third
LarvaePrePupae

MidPupae

Young
AdultsPreAdults

PostPupae
(~)

(-9-)

(~)

2.3

1.7
1.5

1.1

-----------

Or-2
v
bw

E.

0.4
0.4

Be

0.6
0.4

Bed

0.4

w

0.4

3.1
1.9
2.6
2.0
3.0
2.2

4.0
3.1
2.8
2.8
3.4
3.5

3.8
3.0
4.7
3.0
4.7
3.9

1.9
2.6
1.9
3.6
5.4

2.4

1.2
0.8

1.8

0.7

3.3
5.3

1.1

2.1

GENETICS AND CYTOLOGY OF CEREAL CROPS AND
RELATED PLANT GROUPS
20. Studies on the Substitution and Restoration of the Nucleus(By Hitoshi KIHARA)

Two species belonging to two different genera were used in this study,
namely Aegilops caudata and Triticum vulgare. Substitution and restoration of the nucleus were effected by back-crossing the reciprocal hybrids
between the two species to T. vulgare as the male parent.
The first back-crosses (SB I and RBI) had 36-52 somatic chromosomes.
49-chromosome plants were found most frequently. The BI-plants wereagain pollinated with vulgare-pollen.
So far we have obtained SBs- and RBs-strains which had invariably 21
bivalents. Seed-fertility of both strains was normal, while pollen-fertility
was nil in SBs and perfect in RB s.
At least two characters (non-waxy and black ear) were transmitted to
the SB- and RB-strains from Ae. caudata, either by crossing-over, or byexchange of chromosomes during the meiosis in BI.

21.

Cytogenetical Studies on FI Hybrids of Agropyronwith Triticum and Aegilops(By Seiji MATSUMURA, Mikio MURAMATSU and Sadao SAKAMOTO)

The genus Agropyron comprises three sections, namely Euagropyron,
Elytrigia and Roegneria. Intrasectional hybrids are easily obtained, but

RESEARCHES CARRIED OUT IN 1956

37

intersectional crosses are difficult. In section Roegneria, tetraploid A.
yezoense has a genome constitution homologous with that of A. ciliare, but
their hybrid is completely sterile. Also, in section Elytrigia all 3 genomesof hexaploid A. trichophorum and A. glaucum are homologous.
Hybridization experiments between Triticum and Agropyron showed thatthe easiest crosses were those between the Emmer group and Elytrigia
section, while crossing with the Einkorn group was very difficult. F 1
hybrids were obtained between A. glaucum and several Triticum species,
i.e. T. polonicum, T. durum, T. dicoccum and T. pyramidale. They were
nearly or completely sterile. At MI varying conjugation patterns from
311 +29 r to 1211 + ll r were observed and the mode of bivalents was at 7-8.
The F 1 hybrid between T. vulgare and A. glaucum was completely sterileand showed various kinds of chromosome conjugation from 811+26r to1311 +16 r, with the mode at 11 11 . Judging from the occurrence of 7-11
bivalents in these hybrids, allosyndesis of several chromosomes between
the genomes of Triticum and those of Agropyron may be assumed, andmoreover, the possibility of autosyndesis of a few chromosomes between
the genomes of A. glaucum or Triticum is indicated.
Crossing of A. glaucum with three species of Aegilops, i.e. Ae. longissima, Ae. cylindrica and Ae. variabilis, was successful. All hybrids werecompletely sterile. Various kinds of chromosome conjugation were observed from 1m+5n + 15r to IOn +8r in the hybrid with Ae. longissima,from 2m+4n +21r to 1m+9n + 14r in that with Ae. cylindrica and from
5u +251 to IOn +151 in the hybrid with Ae. variabilis. It is noteworthy
that in all hybrids the average chromosome conjugation amounted to 6-7
bivalents suggesting autosyndesis between the genomes of A. glaucum.
The wide fluctuation in the number of bivalents indicates the occurrenceof some allosyndesis between the genomes of the tested Aegilops species
and A. glaucum.

22. Complementary Dominant Lethal Genes in Rice
(By Hiko-Ichi aKA)

Cross combinations showing hybrid inviability, though a rare feature
among cultivated varieties of rice, were found among several varieties
from India, P.T.B. 10, P.T.B. 7, and others. In their hyqrids, the seeds
germinated normally, and the seedlings also grew normally up to the development of the fifth leaf. Subsequently, deterioration of chlorophyll andretardation of growth set in, resulting ultimately in the death of the plants,
unless the environment was favorable. The same cross combinations at

38

RESEARCHES CARRIED OUT IN 1956

the tetraploid level showed a similar behavior. On crossing these varieties
with various others, it was found that this phenomenon was noticed only
among about ten Indian varieties, which could be grouped in two classes
separated by this hybrid inviability from each other.
For studying the genetical basis underlying this phenomenon, two varieties, A and B, whose hybrid is inviable, and a third variety C which
produces normal hybrid plants with either A or B, were crossed in theorder (A x C) x B, or (B x C) x A. The offspring showed a 1: 1 ratio of
normal and inviable plants. Reciprocal crosses gave similar results.
It may be inferred, therefore, that a set of complementary dominantlethals, L 1 and L 2 , govern this hybrid inviability, and the parental varieties
A, Band C are of such genotypes as L 1 +, + L 2 and + +, respectively.

23. Genetic Basis of Hybrid Break-down in Rice
(By Hiko-Ichi aKA)

When distantly related varieties of rice are crossed, it is often foundthat, though the F 1 plants grow normally, showing hybrid vigor, a partof the F 2 plants show a poor growth, death or sterility, possibly due tonon-adaptive recombinations of parental genes. In a typical case of thiskind-a cross between 451 (an Indian variety, Continental group) and 521(a Japanese variety, Temperature-Insular group~-, a genetic experiment
was conducted to investigate this phenomenon. In this cross, though the
F I showed a vigorous growth, about one third of the F 2 plants became
yellowish at the beginning of the tillering stage, and did not grow any
further.
The F I of 451 x 521 (or 521 x 451) was back-crossed to the parents, andthe progeny was examined. It was found that the ratio of normal toinviable plants was 3: 1. The F 2 ratio was judged to be 11: 5. There
was no difference between reciprocal crosses. These segregation ratios
may be explained by asssuming that a set of duplicate genes Al and A 2
are concerned, and that at least two dominant A's, i.e., AlAI, A 2A 2 or
A IA 2, are necessary for normal growth. According to this assumption,
the parental varieties may be considered to be of AIAla2a2 and ala lA 2 A 2
constitutions.
These duplicate genes may be called" complementary recessive lethals,"
since the inviability results from the interaction of the recessive alleles.
In order to test the validity of this theory, 521 was crossed with a variety
647, which gives no aberrant hybrid progeny either with 521 or with 451,
and the F 1 so obtained was again crossed with 451. In the first generation

RESEARCHES CARRIED OUT IN 1956

39

Table 1. Segregation of normal and inviable plants in F z
and back-crosses of 451 x 521.
Cross

Normal Inviable

Exp. Num.
(115)

451 x 521
521 x 451

42
47
89

18
23
41

41.25 : 18.75
28.13 21.87
89.38 40.62
(3 1)

0.044
0.085
0.005

(451 x 521) x 451
q
x 521(521 x 451) x 451
q
x 521

32
47
26
41
146

15
18
9

35.25
48.75
26.25
42.75
153.0

11.75
16.25
8.75
14.25
51.0

1.199
0.251
0.010
0.286
1.281

-

16
58
-

of this cross, all plants grew normally. In the second generation, fourout of nine families showed a 11:5 segregation of normal and non-viable
plants. This may be explained without difficulty by the former assumptionof genes if 647 had A 1A 1 A 2 A 2 •24.

Hypothesis of " Duplicate Fertility Genes" zn Rice((By Hiko-Ichi OKA)

The writer has pointed out earlier that in some hybrids between distantly
related varieties of rice, though the F 1 was completely fertile, sterile
plants occurred in the F z , and that this phenomenon could not be explainedby the hypothesis of Gametic-Development genes, but might be explainedby assuming duplicate genes whose double-recessive combinations lower
the fertility of the carrier. An experiment to support this view was conducted, results of which are reported in this paper.
The varieties crossed, 1 add 719, both belonging to the continental(Indica) group, are completely self-fertile. Their F 1 was also completely
fertile in pollen formation as well as in seed set. However, sterile plants
were found in the F 2 generation; the F 3 lines derived from these sterile
plants appeared to be either pure for sterility or segregated into plants
with varying fertility, as shown in Table 1.
It was found that in the sterile lines, the environmental variance for
fertility was more than four times that found in other sterile rice plants.
This sensitivity of environmental factors may suggest that these sterile

RESEARCHES CARRIED OUT IN 1956

40

lines have a low seed-setting capacity. This may account at least partly
for their wide variation in fertility, as shown in Table 1.
Table 1.
.

Variation in fertility of two rice varieties, 1 and 719,
their hybrids and back-cross progeny.

_~~--

Fertility
Generation in parent 90

80

70

PI (1)931

11

P 2 (719)

2
2

4

3

1

5

6

20

90%(F I)F2

a F 4 line

(Exp.)

6

5

o

12

3

~

32%

1

236

3

1

40%

2

7

12

5

5

10

plantsstudied
10

9

11

13

- - - _ . _ - - _ . _ - - - ~ ~ - -Fax P 2 F I'f
F2(Exp.)

Num.of
20

51

42
46.7

(Exp.-11 : 5)a Fa line% of seed setting
60
50
40
30

13

68

21.3

;(2=1.89
P>O.1
17

4

67

- - ~ - _ . , , -

1

1

2

1

5

9

11

6

5
1

1

1

39
9.2 7.0 5.7 6.0 5.3 3.4 1.6 0.6 0.1 ;("=9.94
P>0.05
1
2
1
1
5
5
20
9
17
16
16
14
8
3
1
109
4.2 17.4 14.6 14.7 15.3 17.7 13.6 7.3 2.9 1.3 ;("=4.28
P>0.50- - - - - - _... _ - - - - - -A few Fa plants with low fertility were back-crossed to the parental
varieties, and variation in fertility in the first and second generations
were observed. The results are set out in Table 1. The back-cross hybrids
were semi-sterile. In the second generation, though fertility appeared tovary continuously, the frequency of fertile plants could be judged to beabout one fourth. The segregation ratio was then explained to be 1: 2 : 1,
and the distribution of fertility was computed under the assumption thatthe variations due to causes other than the genes under consideration,
follow a nomal distribution with the Same standard deviation as that of
the fertile parental varieties in fertile plants, and that of the semi-sterilelines in semi-sterile plants. As shown in Table 1, the observed distributions gave good fits to the expected one thus computed. The second
generation of the back-crosses may then be regarded as showing a 1: 2: 1
or 1:3 ratio.
The results of this crossing experiment may lead to the following assumption of underlying genes: A set of duplicate genes, Al and A 2 (ondifferent loci, independent from each other), are concerned, and plants
with two or more dominant A's (AlAI, A 2 A 2 or A IA 2 ) are fertile, whileplants with one or none have a low fertility. The parental varieties, 1

RESEARCHES CARRIED OUT IN 1956

41

and 719, might have such genotypes as A 1A 1a 2a 2 and ala 1A 2A 2 respectively.
Their F1, carrying A 1a 1A 2a 2, would be fertile, but the F 2 would segregate
into 11 fertile and 5 semi-sterile plants. The F 3 sterile lines (not showing
a segregation) would have alala2a2 constitution, and a fertile to 3 sterile
plants segregation would result if back-crossed to either parent.
The assumed role of the duplicate genes is exactly the same as that
proposed in the foregoing paper regarding inviability of a part of F2. In
both cases, it was assumed that two dominant alleles of a set of duplicate
genes were necessary either for normal growth or for seed setting. It
however appeared that there was a slight difference between A1ala2a2 andalala 2a 2 plants, the former showing a better growth or a higher fertility
than the latter. Further studies may be needed to confirm the validity ofthis assumption. If one dominant gene was enough for maintaining viability, only the double-recessive plants, alala2a2, would be inviable or sterile,giving rise to a 15: 1 instead of 11: 5 ratio. The writer had expected thissituation when starting these experiments. Such a situation may also
actually be present among the commercial rice varieties.
Duplicate genes as pointed out in this paper seem to be widely spreadamong rice varieties. They might bring about the so-called hybrid breakdown in hybrid populations, and might work as an isolating barrier between
distantly related varieties of rice.

25. Karyosystematic Studies in Poaceae, IV(By Tuguo TATEoKA),

An examination of chromosome configurations has been carried out inseveral Poaceae. In 1956, twelve species listed in Table 1 were examined
cytologically. Also, some genera whose systematic position has been disputed were submitted to investigation from the standpoints of systematiccytology and anatomy.
1. Genus Phaenosperma-Although in several respects the external morphology of Phaenosperma suggests its systematic position in Eragrostoideae,
this genus is more closely related to some Festucoideae than to any
Eragrostoideae according to the results of the examination of chromosomes
and leaf structure.
2. Genus Garnotia-To refer Garnotia to Eragrosteae or Agrosteae has
been conveniently adopted by many systematists, but there is no reliablebasis for such views. The anatomical features of the leaf of some Garnotia
species are clearly different from those of the typical members of Eragrosteae and Agrosteae, and at the same time they are suggestive of an

42

RESEARCHES CARRIED OUT IN 1956
Table 1.

Chromosome numbers of some Poaceae.
Species2nBrylkinia schmidtii OHWI
Diarrhena japonica FRANCH. et SAV.
D. fauriei OHWI
Astrebla lappacea DOMIN
A. pectinacea F. MUELL.
Tripogon japonicus OHWI
Mosdenia phleoides STENT
Coelachne japonica HACK.
Cleistachne sorgoides BENTH.
Themeda triandra FORSK.
Schizachne purpurascens SwALLEN
Ehrharta calycina SM.

40
38
38
40
40
20
40
40
36
30
20
24

affinity between Arundinella and Garnotia. However, the spikelet structureof the two genera is clearly different. It seems correct to place Garnotia
near Arundinelleae as an independent tribe, Garnotieae.
3. Genus Thysanolaena-The examination of leaf structure of Thysanolaena supports C. E. HUBBARD'S (1934) opinion that this genus should betreated as an independent tribe. The observed characteristics, as well as
the morphological features, show that Thysanolaeneae and Arundineae areclosely related.

F.

CYTOLOGY AND GENETICS OF NICOTIANA ANDSOME OTHER FLOWERING PLANTS
26.

Cytogenetic Studies on the Genus Nicotiana, IX(By YfJ TAKENAKA, Yoshiyuki AMANO and Tuguo TATEOKA)

The reduction divisions in PMC's were studied in 4 interspecific hybrids:

N. gossei x N. longifiora, N. gossei x N. plumbaginijolia, N. paniculata x
N. tabacum and N. megalosiphon x N. tabacum.
1) F 1 of N. gossei (n= 18) x N. longijlora (n= 10).
At MI in PMC's of the F 1 of N. gossei x N. longifiora, from 0 to 3
chromosome pairs were found, with the mode at 1. The frequency of
PMC's with only univalents followed that of PMC's with one bivalent and,RESEARCHES CARRIED OUT IN 1956.

43

that of cells with two bivalents totalled 20%. PMC's with 3 bivalents
were very rare. KOSTOFF (1943) also found univalents or 1-2 bivanlents
and very rarely 3 bivalents in this hybrid combination. Considering thesmall number of bivalents it is difficult to determine whether the few
chromosomal affinities are allosyndetic between the genomes of both parents
or autosyndetic between the two genomes of N. gossei.
2) F 1 of N. gossei (n=18)xN. plumbaginijolia (n=lO).
Concerning this hybrid or its reciprocal, no report has been yet published,so far as we know. At MI in PMC's of this hybrid, the bivalents ranged
from 0 to 4, with the mode at 2. PMC's with 1 and 3 bivalents were
frequently observed but those with 0 and 4 bivalents were very rare.
Since N. plumbaginzfolia is a species closely related to N. longiflora,
meiosis in F 1 of N. gossei x N. plumbaginijolia should be similar to thatfound in F 1 of N. gosseix N. longiflora. But at MI of PMC's, the former
had one more bivalent on the average than the latter.
3) F 1 of N. paniculata (n=12)xN. tabacum (n=24).
At MI in PMC's of this hybrid, from 0 to 4 bivalents were found, withthe mode at 1. PMC's without bivalents and with 2 bivalents were veryfrequently observed, but those with 3 and 4 pairs very rarely.
GOODSPEED (1954) studied the same hybrid and found from 0 to 4 bivalents, with the mode at O. His observations generally agree with our
results. But in the same hybrid, KOSTOFF (1943) found usually from 2 to
12 bivalents, and one or sometimes more trivalents and multivalents. The
cause of the difference between KOSTOFF'S on one hand and GOODSPEED'S or
our own results on the other is not determined. But KOSTOFF also foundthat the reciprocal hybrid, N. tabacum var. macrophylla x N. paniculata, hadmost frequently 2-5 bivalents. This result approaches GOODSPEED'S andour own findings.
It appears from the results of GOODSPEED and from our own observations
that chromosomal affinities in this hybrid exist rather between the genomesof N. tabacum than between the genomes of both parents, since the number of bivalents is approximately the same as in haploid tobacco (TAKENAKA
and TANAKA 1956).
4) F 1 of N. megalosiphon (n=20)x N. tabacum (n=24).
As far as we know, no report on this hybrid has yet been published.
At MI of PMC's of this hybrid, the bivalent range observed was from 1
to 8, with mode at 3 to 4. This pairing is probably due to allosyndetic
affinities between the genomes of both parents. Otherwise, if we assume
that N. megalosiphon is of amphidiploid origin like N. tabacum, the chromosome pairing observed in this hybrid can also be interpreted as caused byautosyndetic affinities between the genomes of each parent. The number

44

RESEARCHES CARRIED OUT IN 1956

of bivalents found in this hybrid could be, of course, also interpreted as
due to the former as well as to the latter affinities.

27. Cytological Studies in Euphorbiaceae. I. Chromosome
Numbers of Some Species Euphorbiain(By Shohachi SHIMOYAMA)
Chromosomes of Euphorbia have been examined by HARRISON (1930, 1931),
MOYER (1934), PERRY (1943), and D'AMATO (1947) among others. Theirstudies have revealed 6, 7, 8, 9, and 10 as basic numbers for this genus.
The author's observations of somatic chromosomes of root tip cells insome species of Euphorbia found in Japan have shown the following results.
1) E. maculata L.
The materials were collected at Mishima, Shizuoka Pre£. The chromosome number is 2 n= 12. All chromosomes are J-shaped.
2) E. pseudochamaesyce FISCH., MEY., et LALLEM.
Plants examined were obtained at Mishima. Twenty chromosomes werecounted in root tip cells; all chromosomes are of J-shape.
3) E. pekinensis RUPR.
This species is very polymorphic. The materials were collected at
Yamanaka, Yamanashi Pre£., and Nikko, Tochigi Pref. as weli as at
Mishima. The chromosome numbers found are 2 n=28 (plants at Mishima),
and 2 n=56 (plants at Yamanaka, Nikko and Mishima). One pair of large
chromosomes with a secondary constriction was found in the nudes platesof the individuals having 2 n=28. Individuals having 2 n=56, had twopairs of such chromosomes.
4) E. Sieboldiana MORR. et DENCE.
The materials were collected at Mishima. The chromosome number
observed was 2 n=20. The chromosomes, being clearly larger than thoseof the above three species, were V- or J-shaped.

28. Genetics of the Photoperiodic Behavior of the Japanese Morning
Glory, Pharbitis Nil CHOIS. II. Sensitivity of F Plants to Dark Periodj(By Sadao SAKAMOTO)
In order to investigate the genetical background of photoperiodic behavior
in Pharbitis Nil CHOIS. (a short-day plant) two strains with different responses, namely a wild strain No. 856 collected in Nepal and a strain

...

45

RESEARCHES CARRIED OUT IN 1956

called Tendan from North China, have been crossed reciprocally. Tendan
is more sensitive to dark period than No. 856. The sensitivity of F 1 plants
to dark period was measured by the position of the node on the main axis
bearing the first flower bud. The materials were grown in a temperatureand humidity-conditioned greenhouse kept at 30°C and 80% relative humidity under the natural day-length in Misima (35°N). Ten experiments
were carried out successively from March to December 1956.
The average positions of the node bearing the first flower bud in F 1
plants and parental strains are shown in Table 1.
Table I. Variation in the average position of the node on the mains axis
bearing the first flower bud under natural day-length in Misima (35°N).
No. ofI

II~peri~~en~_1

III

IV

V

VI

VII

VIII

IX

X

Date of sowing I Mar.1 Apr.1 May 1 June 2 July 3 Aug. 1 Sep.1 Oct. 1 Nov.2 Dec. 1- - - -----------_._----,

Parents
856
TendanF1
856 x Tendan :I
Tendan x 856 [

2.9
2.9

4.4
2.7

3.0

23.1
4.4

15.3
5.1

7.4
3.6

3.2
3.0

2.8
2.4

2.4
2.2

2.6
1.9

2.9
3.0

3.5
3.1

4.2
5.3

16.3
17.0

6.6
6.9

4.0
4.7

3.0
4.0

2.8
3.0

2.4
2.8

2.2
2.3

00

__.-

----~-----------_._-,-.

00;--_.----

No flower bud was found below the 20th-30th node.

There was no significant difference between the reciprocal crosses. The
sensitivity of F 1 plants was nearer to that of Tendan than to the intermediate values between the parents. Only in experiment IV (sown June2), was the value found for F 1 plants higher than the mean of the parental
values.
Judging from this photoperiodic behavior of F 1 plants, it seems that
Tendan's sensitivity to dark period is prevalent over that of No. 856.

29. Crossing Experiments with Citrullus vulgaris SCHRAD.
and Citrullus Colocynthis SCHRAD.
(By Kazuo FURUSATO and Akira MIYAZAWA)

A cross between Citrullus vulgaris and C. Colocynthis was carried out
with the following results.
1. When C. Colocynthis was the male parent, the seeds did not develop
to maturity and did not germinate. However, parthenocarpic fruits were

46

RESEARCHES CARRIED OUT IN 1956

formed which grew to the_ same size as the fruits of self·pollinated C.
vulgaris. It has been reported (KHOSHOO 1955) that germinating seeds had
been obtained from this direction of the cross. It may be that other varietiesof C. vulgaris behave differently in this respect.
When the reciprocal cross was made, i.e. with C. vulgaris as the maleparent, a great majority of the seeds germinated well, and fruits of normal
size were produced. The F 1 hybrids obtained from this cross direction
showed at first metaphase regular chromosome pairing with lIIl (bothparents have n= 11).
2. When diploid C. vulgaris was crossed with a tetraploid derived fromthe same variety, only non·germinating seeds were produced. But when
diploid C. Colocynthis was crossed with tetraploid C. vulgaris, triploid germinating seeds were obtained which developed into plants of normal growthand size and yielded seedless fruits like the triploid seedless watermelons.
The triploids showed at MI variable chromosome pairing with 11m when
it was complete, and other, secondary, configurations with trivalents,
bivalents, and univalents.
3. When tetraploid C. vulgaris was crossed with the original diploidstrain, germinating triploid seeds were obtained. Also, when tetraploidC. vulgaris was crossed with diploid C. Colocynthis as the male parent,
triploid seeds were produced which gave triploid plants with seedless fruits(Table 1).
Table 1.

Viability of seeds and chromosome conjugation foundin the above described experiments.

Cross combination

Seeds

C. vulgaris (2 x) xC. Colocynthis (2 x)

empty
viableempty
viableviableviableC. Colocynthis (2 x) x C. vulgaris (2 x)
C. vulgaris (2 x) x C. vulgaris (4 x)
C. Colocynthis (2 x) x C. vulgaris (4 x)
C. vulgaris (4 x) x C. vulgaris (2 x)
C. vulgaris (4 x) xC. Colocynthis (2 x)

Chromosome
conjugation
lIn

11m
11 m

4. The F 2 generation and the test cross (F 1 xC. vulgaris) showed asegregation represented in Table 2. C. Colocynthis had fruits with whiteflesh, white seeds and bitter taste; C. vulgaris had fruits with pink flesh,black seeds and sweet taste. In the F 1 the flesh was white, the taste
bitter and the color of seeds was intermediate.
The figures of Table 2 are small but we may assume (1) for flesh color
two genes and the segregation ratio of 9: 7, (2) for taste one dominant•

47

RESEARCHES CARRIED OUT IN 1956
Table 2. C. Colocynthis x C. 'lJUlgaris F 2 and test cross (F1 x C. vulgaris).

White
--

Seed color

Taste

Flesh color
Not white

Bitter

Not bitt.

- - - -

F2

19

v. cr. 18

I

17
86

25
50

Black andinterm.

White- - - - _ .. _ - - - -

2
0

34
104

11
54

- - - ---------

gene and the segregation ratio of 3: 1, and (3) for seed color two or more
duplicate genes.

•

30.

Dextrality and Sinistrality in Plants(By F. A. LILIENFELD and Hitoshi KIHARA)

In Medicago tuberculata WILLD. and M. litoralis ROHDE, both plants withclockwise coiled (right-handed) and counterclockwise coiled (left-handed)
pods occur. Both kinds are constant. Crosses between right- and lefthanded plants were carried out.
In F 1 right dominates over left, and in F 2 monohybrid segregation takes
place.
Ours is the first experiment of this kind carried out with plants. In
the well known animal counterpart, Limnaea peregra, right too dominates
over left but the segregation is delayed and does not manifest itself until
F 3, owing to the maternal influence upon coiling direction.

31. Attempt to Use Disease-Resistant American Varieties in
Triploidy Breeding of Sugar Beets(By Seiji MATSUMURA)

Triploid seeds of sugar beet were obtained in 1954 from intervarietal
crosses between Hon-iku No. 398-4x (No. 4398) and three American 2x
varieties with higher resistance to diseases (US 226, GW 304, GW 443).
Seeds, called 3x-A and 3x-B, were collected from the 4x and 2x motherbeets respectively, planted in the ratio of 3: 1. Comparative studies ofyield, sugar content and disease resistance were carried out in several
triploid combinations and the diploid GW 443 in the experimental fields of
Hokkaido in 1955 (Table 1). GW 443 was more resistant to diseases andgave a higher yield (with a 10-15% increase in sugar content) than Hon-

48

RESEARCHES CARRIED OUT IN 1956
Table 1.

VarietyComparison of disease resistance, yield and sugar content
in several triploid combinations.
1

SusceptiSusceptibility
bilityI (August)_(October)

Yield perTan***1 Rate Index** RateIndex,***
Kin 'Rate

I

I--------------------,-

1)
2)
3)
4)
5)
6)
7)
8)
9)

GW 4434398 x HI t 162
399" xx HIHI 401"" x HI 390
x HI 192
" xUS
226
"
x GW304"
x GW443"

Sugar %

L. S. D. 5%

0.17
1.20
1.43
!
1.17
1.01
0.89
0.47
0.22
0.45
0.41

100;
701,
841
630
595
524
275
129
265

0.99
4.25
4.78
3.28
4.06
2.88
2.43
0.57
1.25
0.79

--

100 5,510
429 5,236
483 5,145 ,331 4.848
410 5,619
291 5,491I
245 5,726
58, 5,824
126 5,568
!
315
1

1

Rate

%

Sugar content per
Tan*
***',
Kin: Rate---------.

100; 14.93
96 14.09:
93 14.55
88 16.00
102, 15.36
I
100 15.70
104 14.88

1

1

1

1

1

106 14.88!
101 15.83
1

1

!,

'

0.71

100
94
97

lOi,
103
105:
100
100
106

820
734
748,
779
866
867
848
864
880
44

1

1

100
90
91
95
106
106
103
105
107

* Tan=ca. 0.1 ha.
** Index=The larger the index, the more susceptible were the leaves.
*** Kin=0.6 Kg.
t HI=Hon-iku Number.

iku No. 192, the most widely grown variety in Hokkaido. The sugar yieldof four triploid combinations of tetraploid No. 4398 with two Hon-iku Nos.
192 and 390 and two American GW 304 and 443, was rather better thanthat of diploid American GW 443, although the Hon-iku combinations weremarkedly more susceptible to diseases than GW 443.

32.

How to Improve Seed Production of Triploid Sugar Beets(By Seiji MATSUMURA and Sadao SAKAMOTO)

In practice, production of so-called "triploid" seeds according to acertain planting arrangement (f. inst. 4x and 2x mother beets mixed in theratio of 3: 1) is difficult, inconvenient and uneconomical for a large scale
seed production by farmers. In order to find a simpler method to produce
triploid beets, mixed sowing of 2x and 4x seeds in several ratios, 3: 1, 5: 1
and 8: 1, has been studied in 3n-No. 1, Hon-iku No. 398-4x x No. 162-2x.
The somatic chromosome numbers of the offspring were determined.
Triploid seeds, obtained from mixed sowing in the ratio of 8: 1, had avery low germination and could not be used in practice. There was no

RESEARCHES CARRIED OUT IN 1956

49

significant difference in germination between the seeds obtained frommixed sowing either in the ratio of 3: 1 or 5: 1. The frequency of 3x
seedlings obtained from the so-called triploid seeds was 45.6%, 46.5%
and 42.496 for the ratios 3:1, 5:1 and 8:1, respectively. The frequencyof 2x seedlings decreased with the increase of the numerical ratio of 4x
to 2x seeds in mixed sowing; namely 50.496, 44.1% and 39.4% in the sameorder of ratios. On the other hand, the frequency of 4x seedlings showed
the inverted relation. namely 4.0%, 9.4% and 18.2% in the same order.
From this experiment the ratio of 5: 1 gave the best results. Therefore,
it is advisable to mix 4x and 2x seeds in the ratio of 5: 1 for a larger
scale production of triploid seeds by farmers.
Moreover, the relation between the frequencies of 2x-, 3x- and 4xseedlings and the rate of germination of triploid seeds were studied in
mixed sowing using the ratio of 5: 1 mentioned above. The 2x seeds
germinated generally earlier than the 3x and 4x. Among the seeds, which
germinated within 6 days after sowing 73% were 2x, while only 36% were
3x and 40% 4x. But, 63% of all 3x seedlings were found from the seeds,
which germinated later between the 7th and the 11th day after sowing.
Thus, to thin out the small seedlings in practical cultivation of triploids,
we should call the farmers' attention to this fact of late germination of
3x seeds. Furthermore, to promote the percentage of 3x plants from
triploid seeds, selection of seeds and seedlings with the help of dominantmarker genes and an increase of self-incompatibility of the parental strains
should be attempted.

G.

GENETICS AND BIOCHEMISTRY OF PIGMENTS AND
OTHER SUBSTANCES IN PLANTS

33.

Anthocyanin in the Fruit-coats of Two Varieties of Egg-plant,
Burma and Black Beauty(By Yukihide ABE and Kanji GOTOH)

It was shown earlier that the formation of acylated delphinidin glycoside (Burma-type) was effected by a dominant gene, whose recessive allele
governs the production of delphinidin 3-glucorhamnoside (Black Beautytype). This view is based upon the results of paper chromatographic examination of the pigments of both varieties and the F l - and F 2 -generationsof their hybrids.

RESEARCHES CARRIED OUT IN 1956

50

In order to obtain further information, the anthocyanin of the fruit-coatof Burma has been isolated in a crystalline state (hair-fine needles) as
picrate. A series of chemical analyses of the pigment converted into
chloride has shown that it is a derivative of p-hydroxycinnamoyl delphinidin
3, 5-diglucoside combined with rhamnose (probably one moL). On the other
hand, the anthocyanin of Black Beauty obtained in a crystaIline form has
proved to be identical with delphinidin 3-glucorhamnoside (Shibata 1956).
Consequently, it may be concluded that the difference between the pigments of the two varieties of egg-plant with regard to chemical constitution is controlled by a single pair of alleles.

34. Further Studies on Paper Chromatography of Anthocyanins:
Examination of Glycoside Types by Partial Hydrolysis(By Yukihide ABE and K6z6 HAYASHI)

The method of paper chromatography of natural anthocyanin pigments
was developed by BATE-SMITH (1950, 1954) and HAYASHI et aI. (1953). Thismethod proved to be effective for the identification of aglycones, but further
studies were stiIl required for identifying the types of glycosides.
In this study, several different types of glycosides, e. g. 3-monoglucoside, 3-monogalactoside, 3-glucorhamnoside, 3-glucoxyloside, 3, 5-diglucoside
and acylated glycosides, were successfully separated by the additional useof several solvent mixtures. On the other hand, it has been found thata stepwise degradation of anthocyanins into lower glycosides, depending
upon the nature of the original glycoside, is clearly demonstrated by paper
chromatograms when the glycoside is mildly hydrolysed.
It is expected that the test of the chromatographic behavior of glycosides in different solvent-mixtures together with the above-mentioned
partial hydrolysis will make the identification of the naturaIIy occurring
anthocyanins more reliable (Bot. Mag. Tokyo. 69: 577-587, 1956).

35.

Dominance Relationships of Flower Color in Varietal F 1 Hybridsof Swiss Giant Pansy, Viola tricolor maxima HORT.
(By Toru ENDO)

Forty-two crosses were made among seven varieties of pansies differingin flower color. The parental varieties were Mont Blanc (white), Rhinegold (yellow), Raspberry Rose (reddish purple), Fire Beacon (yeIlowish

RESEARCHES CARRIED OUT IN 195651red), Lake of Thun (light purplish blue) and Berna (deep purple). All
except the variety Berna showed almost the same pattern in the blotchedparts of the lateral and anterior petals. Reciprocal crosses showed nodifference in flower color.
In the cross within the acyanic group (Mont Blanc x Rhinegold), theflower color was pale yellow. This shows that yellow is incompletely
dominant over white. F 1 hybrids between the acyanic and cyanic groups
generally showed that the anthocyanin-forming ability of the latter group
was dominant over the lack of this ability in the former. In some exceptional cases, however, the dominance relationship was reversed. For
instance, the yellow color of Rhinegold appeared to be dominant over the
reddish color of two varieties, Alpenglow and Fire Beacon. Among thevarieties of the cyanic group, it was found that bluish was always
dominant over reddish and the deeper colors were generally dominant overthe fainter ones. The experimental results so far obtained are not sufficient to determine whether epistatic relations are involved or not in addition to the dominance relationship of the genes. In order of decreasing
dominance, the varieties may be arranged as follows: Berna> Lake ofThun > Raspberry Rose> Rhinegold > Alpenglow ::::: Fire Beacon::::: Mont
Blanc.

36. Chemistry of the Bitter Substance in the Fruits of Citrullus
Colocynthis, SeRRAD.
(By Yoshito OGAWA, Toru ENGO and Yukihide ABE)

Citrullus Colocynthis is a wild species of Cucurbitaceae distributed inSouth Arabia and Western India. The fruits have a pronounced bitter
taste to a great majority of hum:ms. The inheritance of the bitterness
was studied by other members of this Institute, the whole project being
initiated and guided by H. Kihara. A chemical purification of the bitter
substance was carried out.
The flesh of the fruit was mashed and treated with ether or methanol.
The bitter substance could be completely transferred into either ether ormethanol. After evaporation of the solvent a dark green oil remained,
which tasted very bitter. The bitter substance of the oil was stable
either in acidic or in alkalic medium, and stood heating up to lOODC. It
was again treated with ether, and then washed in basic (2N.NaOH) andacidic (2N.HCI) media to remove impurities. In this way the bitter substance was obtained in the ether solvent. This crude material was purified by chromatography on alumina. The result is shown in Table 1.

52

RESEARCHES CARRIED OUT IN 1956
Table 1.

Chromatography on alumina of "Citbittol".

Solvents

No.
I- 1 1 Chloroform
2
"
3
4
5
Chloroform + ether
6
ether
7
8

"

Amount of .
outflowing I
solvent (ee.)

105Comment

Taste
None

Green fatty subst.

"
"

"
"
"
"

"

"

"

"
"

"
"

"
"

"
"
"

9
10

ether +methanol

11

methanol

BitterYellow oil

12
13
14
15
16
17
18

"

"
"
"
"

"
"
"
"
"
"
"

"
"
"
"
"

"

"

"
"
"

None

"

Colorless needle erys.

"

"

"
"

Colorless fine grain erys.

"

Yellow fine grain erys.
._------The purified bitter substance was oily (b.
p. 81°q, and consisted only ofC, Hand O.
By SCHOTTEN -BAUMANN -SKRUP'S method, it
was crystallized as a p-nitro-benzoyl-ester,
composed of colourless needles (m. p. 102°C
from ethanol) as shown in Fig. 1.
The oily bitter substance was named" Citbittol".

P-nitro- benzoyl-citbittol
m. p. 102°C(150 x)RESEARCHES CARRIED OUT IN 1956

H.

53

POPULATION GENETICS AND STUDIES ON
QUANTITATIVE CHARACTERS
37. Genetic Basis of Polymorphism(By Taku KOMAI)

Polymorphism (or morphism in Huxley's terminology) usually develops
in relation to a life in a variable environment or under a variable ecologicalor physiological requirement, especially when the environment or requirement varies from extreme to extreme, such as, from high to low temperature, from dry to wet air, from light to dark surrounding, from concealment to display, as well as for concealment in surroundings of different colors, and mimicry to models bearing different markings. The
polymorphisms are controlled by a simple genetic mechanism. The
dimorphisms so far studied have been shown to be controlled by a single
set of alleles which show a complete dominance-recessiveness relation. If
the heterozygote has an intermediate phenotype, trimorphism may result.
Tetramorphisms seem to be controlled by two sets of para-alleles which
produce allied but distinct phenotypes. Polymorphisms of still higher
orders seem to be due to more than two sets of such para-alleles. Heterosis is apparently an essential property of all polymorphisms. The
numerical ratio among the morphs is kept constant as long as there is nochange in environment or in the physiology of the species. If any change
in the latter takes place, the ratio changes accordingly. If a polymorphic
species inhabits a wide area within which a climatic gradient occurs, acline may develop in the relative incidence of the morphs and genes.
The para-alleles seem to have a heterozygous inversion as the cytologicalback-ground.

'\

38. Statistical Studies on the Breeding Behavior of Wild
Populations of Setaria pumila(By Kan-Ichi SAKAI and Shinya IYAMA)This report deals with an investigation of the breeding behavior of S.
pumila by the method of analysis of variance. This method of investigation, which is described below, will be useful for determining the frequency of occurrence of natural cross-pollination in wild as well as
cultivated plant species.

54

RESEARCHES CARRIED OUT IN 1956

Assume that from a population of a plant species we collect l plants,
each bearing a number of seeds, at random. If we raise m progenies
from each of l plants and investigate n seeds from each offspring withregard to their size, we can construct the following table of analysis ofvariance.
Sourced.f.

Total
Between plants
Between offspring within plants
Within offspring

lmn-l

---

I Meansquare

I

Expectation ofmean square

l-1

rJe2

l(m-l)rJe2

lm(n-l)eJe,2+ rlrJ02 +mnrJ 1,2+ nrJ02-------'--------

From this table we can get the estimated values of 110 2 , 1102 and I1 p 2.
If we denote the frequency of A and a genes in a population as x andI-x, the frequency of AA, Aa, and aa may be written as x-y, 2y andl-x-y. Let the frequency of occurrence of cross-fertilization be q, thenthe components of genetic variance included in 110 2 and I1 p 2 will become
11 P 2.•[(2-q)2(X-X 2- ~y)l D

11 o2..

[qx(l-x)(2-q)+ ~y(2-2q+q2)lD ,if there is no dominance, no epistasis and no linkage between the genes
concerned. D in these formulas stands for genetic variance due to additive effect of genes. The value of y in a perpetuating wild population
will be (NEI, 1953)y2qx(l-x)l+q

if the population has been unaffected by the pressure of natural selection
with regard to the character under discussion.
Thus we get
I1 p 2=x(l-x)(2-q)2/(1 +q)

andl102=qx(l-x)(4-q)/(1 +q)

and

Seeds taken at random from the wild populations of Setaria pumila weregrown in the experimental field and the harvested seeds were measured

RESEARCHES CARRIED OUT IN 1956

55

with regard to their length and width. The result of analysis of varianceof the length and width of seeds is presented in Table 1.
Table 1.

Analysis of variance of length and width of seeds in the progenyof Setaria pumila and the estimates of rJ.2, rJ02 and rJ p 2 •----_.-

Sourced. f.

Between parents
Between offspring within parents
Within offspring
-~

----

Seed
length195310220.251630.06772
0.00429

Seed
width

0.187420.059160.00279

-

II

-----

Expectation ofmeans square

rJ.2+15rJ02 +54.31rJ p2
rJ.2+15rJ02
f1e?
------

i
I

~

i

--

- -

Mean squareI-

0.00429 II 0.00279
0.00423 0.00376
0.00339 I 0.00236

I~-

The values of q for length and width of seed computed on the basis ofestimated values of variance components were 67 and 76%, respectively.
It should be noted in this connection that the correlation between length
and width of seed was +0.6251 in the experimental material under discussion.

39. Genetical Studies on the Cherry-Red Leaf in Tobacco Plants(By Kan-Ichi SAKAI and Shinya IYAMA)'It

In the last issue of this Annual Report, it was stated that the cherryredness of tobacco-leaf was a heritable character in the Bright Yellow
variety. In 1956, three lines from each of six line-groups were grown for
the examination of cherry-red leaf character. The examination was also
made for a number of F 1 hybrids between lines. The first experiment
was conducted by the randomized block method with two replications, eachplot containing 12 plants. The second experiment was conducted by thesame method with three replications, each plot containing 15 plants. Seven
leaves from each plant were harvested and, after drying, they wereclassified into 5 classes ranging from 0, showing no sign of cherry-redness,
to 4, showing the highest degree of occurrence. The class vaiues were
weighted so as to make the ratio of the between-plant variance over thewithin-plant variance maximum. On the basis of this weighting, the score
X was constructed for individual plants. The formula for the year 1956

56

RESEARCHES CARRIED OUT IN 1956

was as follows:

where Xi stands for the number of leaves within plant individuals of thei-th class of cherry-redness.
The analysis of variance of the scores showed that the variation amonggroups of lines was highly significant while that among lines within groups
was non-significant (Table 1).
Table 1. Analysis of variance of cherry-redness of harvested leavesof 18 lines belonging to 6 groups of the Bright Yellow
variety of tobacco plant (1956).
Sourced. f.

Mean square

Expectation of m.s.

Between groups

5

0.2455**ae2+ra,2 +r7lag 2

Between lines within groups

12

0.0145(Je'2+r crs 'l.

Replication

1

0.0880*Error

170.0125

----

-

-----

ae2
- - - - - - ~*, ** Significant at the 5% and the 1% level, respectively.
r: Number of replications.
71:
Number of lines per group.
as 2 : Variance due to strain differences within the same group.
ag 2 : Variance due to group differences.
2g2
h2= 2 a 2/) 0.863.

+t

ag +as + aer

Table 2. Analysis of variance of the cherry· redness of dried leaves of
18 lines of the Bright Yellow variety of tobacco plants obtainedin two successive years, 1955 and 1956.
d. f.

Mean square

Between lines

17

0.1649**Between years

10.2013**

Lines x years interaction

17

0.0149Between plants within strain within year

54

0.0156

Source**Significant at the 1% level.

57

RESEARCHES CARRIED OUT IN 1956

Data of 1955 and 1956 were tested statistically; the result of the analysis
of variance is presented in Table 2.
The table shows that yearly effect was significant for the occurrence ofcherry-red leaves, though the interaction between years and strains was
insignificant. It is concluded accordingly that lines of high occurrence ofthe cherry-red leaf character in one year seem to be high in another year
and lines of low occurrence in one year low in another.
To find dominance relations, if any, of genes responsible for the cherryred leaf character, two groups of crossings were made. In one group,
the No. 1 line which was of low occurrence of cherry-redness served asa constant parent crossed with four different lines, and in the other group,
the No. 13 line which was of high occurrence served as another constantparent crossed with the same four and one other line. Crossing was madereciprocally, and the occurrence of cherry-redness in two constant parents
and five different parental lines as well as in reciprocal F 1 hybrids arepresented in Table 3.
Table 3.

Occurrence of cherry-red leaf character in various F 1 hybrids
among different lines of the Bright Yellow variety.

CrossesI - - Reci~roc.alsI
1- Con- 'C
d I MidGroup-- - - - - - Average stantr?sseparental_ _~_M_a_tin~_ I cilen~ce I Mating , cil:~ce'parent ~ne__ value
'I

'I

1

(l)x(7)(1) x (15)( 1)I0.3068; (7)x(l)0.4152 (15) x (1)0.18330.14610.24510.28071.

0.08320.0832

0.48110.45130.28220.2668~ :;: ~:~: ,J~:I ~~~~ ~. ~- ~ ~ ~:~~~~, ~:~~:~, ~:~:~~I ~:~~:~I ~:~::~
1i

Average(13)1

1_0.142~1 0.1850_ 0._~832,_0__29_60~~~~0.2280(13) x (1)(13) x (15)(13) x (1)(13) x (22)(13) x (29)0.29570.39090.21130.07370.1362(1) x (13)(15) x (13)(1) x (13)(22) x (13)(29) x (13)0.3334'0.27050.14090.1846 ,0.1274'

Average' 0.2216----- - - - -----0.21140.31460.33070.17610.12920.13180.2049'0.20490.20490.20490.2049,0.21650.20490.4811 ,0.45130.08320.04670.0392,---

0.34300.32810.14410.12580.1221I

0.2203-------,----

The analysis of variance of data showed that statistically significant differences were found between different hybrid combinations and that, inthe (1) group, there was a significant difference between reciprocals though
no definite maternal effect was established. The data listed in Table 3
show that only a slight dominance effect, if any, was present.

RESEARCHES CARRIED OUT IN 1956

58

40.

Change of Genetic Variance in Quantitative Characters Due toChange of Gene Frequency in Hybrid Rice Populations(By Hiko-Ichi aKA)

In populations of hybrids between distantly related varieties of nce, it
is often found that the relative frequency of allelic genes is modified due
to gametic and zygotic selection. It may then be surmised that polygenes
for quantitative characters are also influenced, resulting in a change in
genetic variances of those characters.
Let us consider an allele pair A -a which contribute increments d, hand-d in AA-, Aa- and aa-plants respectively. Since selection for heterozygotes is not so important in autogamous plants, we may assume for thesake of simplicity that the only role of selection is to change the relative
frequency of dominant and recessive homozygotes. Then, denoting thedifference in frequency between AA - and aa-plants by x, the frequenciesof AA-, Aa- and aa-plants in F n will be written as1

1

2

2n - 2

--

1

+--x

-

1

-

'2n- 1andConsidering many similar genes with additive effects, the mean value ofthe population from the mid-parent point will be 1j2n - 1 Sh±Sdx, and thevariance can be written as
Sd2-S(dx)2 +(_11_) Sh2 ± 2...1. Sdhx .
( 1__1_)2n-1
2n-1 4n-1
n- 2

Since the effect of selection becomes manifest in later generations where
the effect of dominance is much reduced, the assumption that d, h and x
have no co-variation among one another may not lead to a serious error.
Under this assumption, Sdhx can be assumed to be zero. Assuming
further that d 2 and x 2 are not correlated, S(dX)2 can be regarded as equivalent to ;j32Sd2. Substituting D, H and X for Sd 2, Sh 2 and x2 respectively,
and denoting the environmental variance by E, the variance can be written as

1 _X)D+(-.ln 1
( 1__
2n 21

l )H+E.

4n - 1Thus, the decrease of genetic variance due to the change of gene frequency can be expressed simply by XD. From this, formulas for different
hybrid populations may be derived as follows:,

59

RESEARCHES CARRIED OUT IN 1956

These formulas indicate that, if the genetic variance found in F 2 istaken as the standard, the mean variances of families in F 3 and later
generations appear to be larger than the values commonly expected. The
variances of family means may, however, appear to be smaller, since thevalues of X's may have a tendency to increase markedly with the advanceof generations.
Table 1.

Observed and expected values of variances, with and without
the effects of selection being considered (heading date).

===~------------- ---===---- - - - - - - - - = - - = = = = = = = =Expected, Selection being

Generation

Observed_ _ _ _ _ _ _ _ _ _ _ I_ _ _Consid~~~. __ Not consi~~ed_

~.G

~.~

40.17
18.54

54.87
13.29

35.11
42.13
12.64

38.77
38.47
10.93

63.36
63.05
8.30

25.15
33.69
9.21

29.94
29.41
7.12

67.57
67.04
5.81

Sum of squares of deviations

121.11

4,659.80

VF.
WFs!F.

TTF.
V F5
W F 4/ F 5
VF"

35.63
44.68
16.28

I

___________ J_

The Pei-kuxTaichung No. 65 cross was propagated in bulk up to F 5 ,and about 40 lines were taken at random from each generation. They
were arranged, together with plots belonging to F 2 and the parental varieties,
according to the randomized block design, and various agronomic charaters

60

RESEARCHES CARRIED OUT IN 1956

were measured on a single plant basis. The variance components, D,
Hand E, of heading date were partitioned by the method described by
Mather, using the data for F 2 and Fa. The observed values of variances
gave good fits to the expected ones. However, having put those valuesof D, Hand E into the formulas for F4 to F 6, it was found, in general,
that, if the effect of selection was not considered, the observed values ofmean variances of families were much larger than expected, while theobserved values of variances of family means were smaller than expected.
This finding suggested an effect of selection. Then, by using the formulas
given above, the values of X's for successive generations were estimated.
It was found that XF2=0.186, XFa = 0.409, XF4=0.543 and XF5=0.682. As
shown in Table 1, the observed values of variances gave good fits to the
expected ones obtained by inserting these X's into the formulas. The
analysis of variance of the deviations between observed and expectedvalues indicated that the effect of selection, or the change of gene frequency, was highly significant.

41.

A Method to Estimate the Effect of Linkages between
Polygenes in Autogamous Plants.
(By Hiko-Ichi aKA)

When two genes A-a and B-b are linked, the recombination value beingp, the genetic variance due to those genes in F n is given by

where d a, db, h a and h b are additive (d) and non-additive (h) increments
due to those genes. The above formula would be too complicated to be
used for numerical calculation. An attempt to transform this formula intoa simpler one is reported in this paper.
It has been demonstrated by Mather (1949) that the effect of linkage on
a quantitative character becomes conspicuous only when the recombination
value is around 0.25. Therefore, if we assume that P=0.25 in the above
formula, then the effect of linkage can be approximately shown by the
relative value of dadb to da'+db'. If we consider many sets of such linked
genes, letting S(da'+db')=D, 2S~db

q, S(ha'+hb')=H and2~~]zb =r ,

61

RESEARCHES CARRIED OUT IN 1956

we have the following expressions for the various hybrid populations.
·11

VF 2=2 (1±*0.5 q )D+

4 (1+0.25r)H+El

1

1

-

1

1

Vi. =

1

-

1

VF 3 =-i (1± 0.5 q) D +16(1+0.25 r)H+E2
VF 3=-4(1±0.25 q)D +8 (1+0.1563r)H+E 1(1±0.4167 q)D+:i ~ +0.5208 r )H+E2
1

VF 4 =S(1±0.125 q )D+ (1+0.0976 r)H+E1
16

Vi<\= ~ (1±O.375q)D+ 2~i-~ +0.2790 r )H+E2.1
1
VF5= 16(1±0.0625 q)D+ 32(1 +0.0610 r)H+ E 1* + .. ·coupling; _ ... repulsion.
Table 1.

Observed and expected values of variances, with and without
consideration of the effects of linkage and selection.
(Plant height in logarithm)
Expected values, considering

Generation

Observed
valuesV F3/Linkage &Selection

Linkage
onlyNone ofthe two.021,38.021,43.023,16.015,09

Vi.
W F3 /F•
VF•.027,42.014,66.022,00.022,13.019,96.022,43.022,67.020,52.017,41.013,87.011,55.011,38

VF5
WF./F5VF5.033,06.027,07.017,34.031,63.028,50.015,91.029,49.026,36.013,07.014,46.011,39.009,53

VF 6
W F5 !F6V F6.031,35.026,18.010,51.030,59.026,96.011,93.033,41.029,78.010,46.014,64.011,10.008,61.000,06.000,13.001,51- - - - - - - , .. _ - - - - - - - - - . -Sum of squaresof deviations•... _ - _ . _ - _ . - - - - - - - - ' - _ . _ -- - - ~ - - - - _-----.-RESEARCHES CARRIED OUT IN 1956

62

It is usually experienced in rice that plant height, panicle length, andother dimensions in length of various organs show a significant effect oflinkages in repulsion phase. (Since these characters usually involve geneinteraction, a logarithmic transformation of the scale seems necessary.)In the Pei-ku x Taichung No. 65 cross referred to in the foregoing paper,
the partitioning of variance components with respect to these characters,
based on the data for F2 and F 3 , was carried out, and the expected valuesof variances in F 4 to Fa were calculated from those values of variancecomponents. The results are shown in Table 1.
As shown in the table, under the assumption of Mendelian segregation,
the observed values were found to deviate widely from the expectedvalues. If the effect of linkage was considered by the method mentioned
above, the deviations were largely reduced. By considering also the effectof selection (or of the change of gene frequency), the deviations were
further reduced. It then seems that the effect of linkage can be approximately measured by the present method.

42.

GenotYPic Correlations Among Five Economic
Characters in Egg-plant.
(By Kanji GOTOH)

This experiment is a part of a series of investigations on the inheritanceof quantitative characters in eggplant.
45 randomly selected lines, each from F 3 and F 4 generations of a hybrid
between two varieties, Kikunaga and Sendai-naga No.1, were grown inexperimental plots arranged according to the randomized block design with
two replications. Plant height, stem diameter, period from seeding toflowering, shape index of fruit and fruit number were recorded on an
individual plant basis.
Analyses of variance and covariance of the data obtained were conducted
on a plot mean basis, and genotypic variances and covariances were estimated for each character and for all combinations of the characters.
One of the parents, the Kikunaga variety, belonging to the late maturing
variety group, was of erect growth with thick high stem, while the otherparent, the Sendai-naga No.1 variety of the early maturing variety group,
was of prostrate growth with slender branches and fruits. The latter
variety produced far more fruits than the former.
Analysis of the data showed that the genotypic correlations were positiveand high for the following combinations of characters: plant height-stem
diameter (1.006 in F 3 and 0.717 in F 4 ); plant height-period from seedingRESEARCHES CARRIED OUT IN 1956

63

to flowering (0.624 in F 3 and 0.410 in F 4); stem diameter-period fromseeding to flowering (0.889 in F 3 and 0.882 in F 4). These facts suggestthat such agronomically important traits as described above may bestrongly governed by closely linked genes or by genes exhibiting pleiotropic effects.
Genotypic correlations between shape index or fruit number per planton the one hand and the other characters on the other hand were rather
low and probably of little genetic importance.
The genotypic correlations obtained generally showed higher values thanthe corresponding phenotypic correlations.

43. Genetic Variation in Heading Date in a Local
Variety of Barley, " Aokei No. 14".
(By Kanji GOTOR)

The writer has pointed out before that the variation in heading data of
the barley varieties, "Hosogara No.2" and" Iwate Mensury No.2",
are mainly due to the genetic heterogeneity of the populations. Additional
data obtained with another barley variety, "Aokei No. 14 ", are describedin this paper. The variety was obtained from the Aomori Agr. Exp. Sta.
Date of heading was recorded on a plant basis in 1954, and in 1955 200
derived lines were grown in a randomized block arrangement with two
replications. Records of heading data were taken on a line basis.
According to the data obtained, the range of variation in the date ofheading was 42 days (from March 29 to May 10) in 1954 and 38 days
(from March 24 to May I) in 1955. The correlation coefficient between
parents and offspring was +0.904 and was statistically highly significant,the parent-offspring regression coefficient was as high as 0.785.
From a visual inspection it was found that ., Aokei No. 14" consistedof two distinct groups. One of them was an early maturing erect type
and the other a prostrate type, though within each group variability was
noticed in heading date.
This variety was also heterogeneous with regard to the presence orabsence of hairs on the leaf sheath, 53.3% of plants being pubescent. No
association was found between hairiness and maturity. The three barleyvarieties so far studied ripen simultaneously when grown in localities
where they are adapted. However, they showed a wide variation in ripening time when grown in Misima. One of the important environmental
factors causing such a variability may be the different length of thewinter days in both localities.

64

RESEARCHES CARRIED OUT IN 1956I.

STUDIES ON THE TECHNIQUE OF BREEDING

44. Method of Estimation and Use of Genetic Correlationin Forest- Tree Breeding.
(By Kan-Ichi SAKAI)

One of the most difficult problems in forest-tree breeding lies in the factthat trees often need too many years for reaching maturity. The author
introduces a method of estimating the value of the genetic correlation bet·
ween a character that will be expressed after a tree grows up and somemore or less related character measured in a young stage of the tree. It
is assumed that the trees in a population produce seeds by random pollio
nation.
Let the phenotype of a character A, e. g. trunk size, of a grown-up
tree in a population be PI, the phenotype of some more or less relatedcharacter B, e.g. growth rate, of the tree's offspring in the nursery be P 2 ,and the phenotype of the character A', corresponding to A of parent tree,
which will be realized after the young trees grow up be P a• Figure 1
illustrates the relation among those three characters.
Hi and E i in the diagram standrespectively for genotype and(A)(A')
environment taking part in theexpression of the phenotype
Pi. hi stands for the squareroot of the heritability of thei-th character. YljP and riPstand respectively for thephenotypic and genotypic cor·
relation between the i·th andj -th characters
Then, we getandFigure 1. Path diagram illustrating p:leno·
typic and genotypic relationships between
mother trees and their offspring.

because the parent plants are
assumed to be pollinated at
random in the population.
Thus we come to have theequation,

RESEARCHES CARRIED OUT IN 195665

in which h z is the square root of the heritability of the character of theyoung trees in the nursery and will be found by the method of analysis
of variance. To find the value of hi is impossible, but if we assume thatthe heritability of trunk size of mature trees be not much different fromthe heritability of growth rate of young trees, we can find the genetic
correlation between P z and P a, making h1=h z, as

Selection of mother-trees on the basis of characters of offspring willbring the genetic gain

where .:lG z and .:lGa stand respectively for the genetic gain in the character of trees after maturity and for that in the character of young trees
by selection on the basis of young trees. djU is the square root of genetic
variance of j-th character. The i is the selection differential. Thoughda H is impossible to find, the ratio (d3H/dl') will take a constant value fora given population. If we assume that d3 H = dz H , the approximate amountof genetic gain to be expected by the selection may be computed.

45.

Application of the Coefficient of Relationshipin the Breeding of Autogamous Plants(By Kan-Ichi SAKAI)

The coefficient of relationship may be useful in the choice of parental
strains for hybridization in the breeding of autogamous plants. The relationship between parental strains
and the pure-breeding lines derived
Parentfrom the cross of the parental
AABB
aabb
strains is illustrated in the following table. In this case parents --~A~--I
1o
are assumed to be AABB and aabb.
I
AAbb
i
t
Accordingly, the relation between
aaBBtiparents and offspring is on theaabb
o1average,

66

RESEARCHES CARRIED OUT IN 1956

R po = 1+~+!+!+J±1 = 1

8

2Similarly, the relationship between two lines taken at random from thesame cross will be on the average,
Roo=it .

If two pure-breeding hybrid lines are selected from the same F" line, therelationship between them will be
Roo(F,,)=lX(1--2';_2)+ ; (2 L2)=1- 2';-1 'because the probability of a gene pair being heterozygous is 1/2"-2 andthe probability of being homozygous is 1-1/2"-2. For a new line selected from an already established variety by the method of so-called
pure-line selection, the relationship between that line and its parent or the
relationship between two selected lines cannot be determined exactly, but
it will be in the range from 1 to !.

On the basis of such relationships, we can compute the coefficient ofrelationship between two strains by looking into the pedigree. The following is an example showing the pedigree of two wheat varieties, A and B,
explaining the method of computing the coefficient of relationship between
them as well as between them and one of the parental varieties.
A

8

RAB=clr~ge+chkle=(~)4+m5=O.094
Rp3A=ch=(~)2=O.25

R p3 B=egh+elk=2x W3=O.25 .

The coefficients of relationship among parental materials will help thebreeder to plan his crossing program.

RESEARCHES CARRIED OUT IN 1956

J.

67

STUDIES ON COMPETITION AND MIGRATION
46.

Competition between Different Species and Species
Hybrids in Nicotiana.
(By Kan-Ichi SAKAI and Takashi NARISE)

Competitive ability of three species of Nicotiana, viz., N. sylvestris, N.
tomentosijormis and N. Debneyi, and several species hybrids was tested
using the Bright Yellow variety of tabacum as the standard. The hybrids
were: F 1 and amphidiploid hybrids between tabacum and sylvestris, abackcrossed progeny of the amphidiploid by tabacum, the F 1 hybrid between sylvestris and tomentosiformis, and the amphidiploid hybrid between
Debneyi and tabacum.
Pure-stand plots of Bright Yellow and mixed plots of that variety withdifferent species or species hybrids were arranged according to the randomized block design with three replications. The mixture was made byalternate jllanting of plants of the test variety with those of the tested
species or species hybrids. The distance between adjacent rows was 90
cm and the interhill spacing within each row was 45 cm.
Plant height, number of capsules, plant weight and number of leaves of
the test variety Bright Yellow in pure-stand plots and mixtures were recorded on an individual plant basis.
Table 1. Plant weight (g) of the test variety Bright Yellow inpure-stand plot and in competitive plots with other species
or species hybrids, on individual plant basis.
BrightYellow(control)Competingspecies

BY syl 'IB.Y.XSYlV.
sylvestris B.Y. x sylv. A· . xh · 2Xv . Amphi·2X
mp 1xB.Y.

I.."---~-"."----i---------,-Plant weight(g) of the
327.3
404.9
Bright Yellow
variety
I
I'

~,-"-

--- -----

313.9

296.3

·~_._~c~_·~_r_;i~: __'__:!~ _T_fi_r;:_:_~_~O_s~_i-_-;-· _t_o_~_~F_~_~ _;_if_. _1_
358.8- - c._D_T_m_ep_yh_it_-2_~_·

D ebl1_ _ _ey_i-_"

Plant weight(g) of theBright Yellow
variety

273.8

409.2

451.2

446.5

Y_.

68

RESEARCHES CARRIED OUT IN 1956

Analysis of variance of the data obtained showed that the competitiveeffect of different species hydrids on tabacum was statistically highly significant. Data on plant weight for Bright Yellow in pure-stand plot andmixtures are presented in Table 1 as an example.
It should be understood that species which caused Bright Yellow to havea smaller weight were stronger in competitive ability than those whichallowed it to have a larger weight. Thus, the following order of species
and species hybrids with regard to their competitive ability has been
established:
(1)

(2 )

(3)

B. Y. ~ SYIV:) xB. Y.
( Amphl-2X> (B. Y. x SYIV.) > (B. Y. ~ SYIV.)
F1

Amphl-2X> sylv. >B. Y.
Sylv. > Tomentosiformis > (SYlv. x tomentosif.)
F1

DebneYiXB. Y.) > D b 'B.Y. > (Amphi-2X=
e neYt

The conclusion drawn from this experiment is in agreement with theprevious findings that competitive ability of a hybrid in comparison with
its parental species is dependent upon the genetic constitution of theparental species and that doubling of chromosomes in F 1 producing anamphidiploid decreases the competitive ability.

47. Competitive Ability of Barley Varieties at Various
Fertility Levels of the Soil.
(By Kan·Ichi SAKAI and Hiko-Ichi OKA)

Competitive ability seems to be controlled by genes. It becomes thenof great interest from plant breeding as well as from evolutionary standpoints to find if there is an interaction between the effect of those genes
and some environmental conditions. OKA and SAKAI (1956: the last issueof the Annual Report of this Institute) described the results of their experiment on the effect of soil fertility on survival rates of two mixed rice
varieties. The present report deals with the effect of various fertility
levels of the soil on the expression of competitive ability of seven varietiesof barley.
The seven varieties used are: Kagosima-Kobai-1, Sizuoka-Siro-6-rowed1, Kuromugi-48, Sakigake, Kanto-Kawa-2, Suifu, and Siro-Chinko. Six
fertility levels of the soil were prepared by applying the following doses

69

RESEARCHES CARRIED OUT IN 1956of the standard mixture: 0,1/4,1/2,1,2 and 4. Each variety was grownin a pure-stand plot and in a mixed plot with the Siro-Chinko variety
which served as a test variety of the competitive ability of experimental
plants. The plots were arranged according to the split-plot design withfour replications, in which the main-plots differed with regard to soil fertility.
Plants in the plots with no fertilizer were damaged seriously by frost
during the winter. Plants grown at the lower levels of fertility also showedsome damages. Thus, the statistical analysis was made separately foreach fertility level, the no-fertilizer plots being excluded from the analysis.
The analysis of variance of plant weight of the test variety" Siro-Chinko" is presented in Table 1.

Table 1.

Fertility
level,

Analysis of variance of plant weight of the test
variety at different levels of soil fertility.
1

1/2

1/4

2

4

1

Source1d.d I M.S. d.d

M.S. 1d.d

M.S. I d.dM.S.

d.d 1 M.S.

R-e-p-l-ica-tJ-'on---2fl48~i-:- 2-123.3 1 3180~5 --3-----5-9-.6--'--3Competition
Error

6,
11

69.4
44.8

6! 61.4*1
I 15.2,

10

6
17

98.8
59.71

1

6
17
.._..

------"-_

356.0**:
48.2_--_._-~-

480.2

6
653.5**
17, 125.4._------------t

One or two missing plots are involved.
*, ** Significant at the 5% and 1% level, respectively.

Table 2. Analysis of variance of plant weight, weight of ears and numberof ears of the S-S-6-Rowed variety in pure-stand plots and in
mixture with the test variety.
Mean squared.£.

SourcePlant
weightof-- we~~~J ofl Number
ears
----

----~-

Replication-1--34 'Fertility level
Competition (Pure: Mixed) I
Fertility x Competition
Error
1

1
4
27

134.0
5520.7**2748.5*319.3*
90.8

14.6
926.1 **
469.7***, ** Significant at the 5 % and 1 % levels, respectively.

42.1
20.3

I

4.8
384.2**
77.4*
8.9*
2.3

70

RESEARCHES CARRIED OUT IN 1956

The analysis of variance shows that the effect of competition tends tobecome more significant at the higher levels of soil fetility. Of the sevenvarieties, the variety Sizuoka-Siro-6-rowed appeared to be the strongest
competitor, so the plant weight, and the weight and the number of ears
per plant of this variety in pure-stand and in the mixture with the SiroChinko variety were analyzed statistically. The results of analysis ofvariance are presented in Table 2.
This table shows that the effect of competition as well as the effect ofinteraction between fertility and competition are statistically significant inall characters but one. Plant weight, ear weight and ear number of the
Sizuoka-Siro-6-rowed variety in pure-stands and mixtures at five kinds offertility levels are presented in Table 3.
Table 3. Plant weight and weight and number of ears per plant of the
S-S-6-rowed variety in pure-stands and in the mixtures with thetester variety at 5 different levels of soil fertility.
Fertility level

1/4

1/2

1

1

2

4

l.p~re-: Mix- I Pure'! MiX-l P~~e-I Mix- ! Pure'! Mi~~I· P~~e-IMix. stand ture I stand ture stand ture stand ture standi ture

Pla~~-weight (g) 1.113~i 107.1 1173.1 238.21245.5 299.1 11.301.3 389.3 \.301.0 432.6
Weight of ears (g)i 11.77 11.61117.30 23.18124.96 32.96 31.54 39.28 31.09 43.76
1
Number of ears i 4.09 3.93 6.26 9.161 9.71 11.79 14.93 18.36 18.49 24.151-------------------------

48. Correlation between Competitive Ability and Other Charactersin Hybrid populations of Rice
(By Hiko-Ichi OKA and Kan-Ichi SAKAI)

The writers have been interested in the study of variation in competitive ability among varieties or strains derived from varietal hybrids ofcultivated plants. This paper deals with correlations of competitive ability
with other characters or gene differences in competitive ability found in
hybrid populations of rice. FlO strains of P. T. B. 10 (an Indian variety,
Continental or Indica group) x Kinoshita-mochi (a Japanese variety, Temperate-Insular or Japonica group), and F g strains of Pei-ku (a Formosan
native variety, Continental group) x Taichung No. 65 (a Horai variety of
Formosa, Temperate-Insular group), were used as materials. Competitive
ability was measured, in the experiment with the first cross, by the
panicle number of the "tester" variety mix-planted with each strain, and,

RESEARCHES CARRIED OUT IN 1956

71

in the experiment with the second cross, by the panicle number of eachstrain mix-planted with the" tester" variety; in both the cases, the difference in panicle number between the mix-planted and singly-plantedplots was used as the measure of competitive ability. The field experiments were carried out in the Taiwan Provincial College of Agriculture
in Taichung, Formosa.
The correlation coefficients found between the competitive ability andother various characters were as follows;
Correlation coefficients with competitive ability.
Characters
Plant height
Panicle length
Panicle number
Seed number per plant
No. of Days of growing period
Length/width ratio of grain
Weight for shedding
Index-number of alkali-test
Germination speed*

First Cross

Second Cross

0.30~

-0.08

0.14
0.16
0.12
0.31
-0.18
-0.30*
0.14

-0.14
0.25*
0.17
0.13
0.02
-0.16
0.07

Between the 5% and 1% levels of significance.

The correlation coefficients given above suggest that competitive ability
is not correlated with any specific agronomic character. It appears thatvariation in competitive ability in hybrid populations may not bring abouta change in quantitative characters, so far as the phenotypic measurement
is concerned. However, characters which distinguish distantly related
varieties generally showed a correlation with competitive ability; strains
with characters similar to the varieties of the "Continental" group tended
to show higher competitive abilities than those similar to the varieties ofthe "Insular" group. The corresponding tendency was also found between
competitive ability and the degree of hybrid sterility with the parental
varieties, when the strains were crossed with both parents. It was further found that strains with genes derived from a parental variety belonging to the Continental group, i. e. Ph (Phenol reaction), Rc (Red seed coat),and c (colorless apiculus), had higher competitive abilities than those withthe genes allelic to them, derived from a parental variety belonging to
the Insular group. This tendency was most marked in the seed coatcoloration gene Rc,

RESEARCHES CARRIED OUT IN 1956

72

49.

Experimental Studies on Migration Using " Population- Tubes"
in a Strain of Drosophila melanogaster.
(By Kan-Ichi SAKU, Takashi NAR13E, Yuichiro HlRAIZUMIand Shinya IYAMA)

To inquire into the problem of migration in relation to competition in
Each population
tube had three radial branches protruding from its periphery, and a number of the tubes were connected with each other (See DIS 30: 166. 1956).
Using a set of four population-tubes as shownin Fig. 1, migration wasstudied with a laboratory
strain of Drosophila meA certain
lanogaster.
number of flies of theSamarkand strain were
kept for one day in a tube,
and then the tube wasJonnected with three newtubes. One experiment
dealt with the relation
between the number ofFig. 1. Photograph showing a set of 4 populationmigrated flies and thetubes connected with each other by radial
period of time during
branches.
which the migration wasallowed to take place. This experiment gave the following result.
It seems that mass migration has occurred in the first 6 hours if thenumber of flies in the original tube was more than 150, though the mig-

Drosophila flies, "population-tubes" were constructed.

Table 1.

Initial no. offlies in theorginal tube

Number of flies migrated in various periods of timeafter establishing connection with new tubes.
No. ofreplications% of flies migrated to new tubes after

6hrs .

24

48

96

72

120

144

I

100-149
150-199
199-249
250-300

5
4
4
5

1.84
14.66
14.92
19.59
..

0.95
11.02
14.47
21.35

2.25
13.31
15.41
24.39

_ - - - - - - - - - ~ ~ -3.32
14. 5118.47127.55

15.52 ; 6.51! 7.21
20.95 I 22.4i 25.01
23.50 I 24.59I 24.00
29.90 I 32.46 32.91
1
1

73

RESEARCHES CARRIED OUT IN 1956

ration continued even after that time. Migration taking place after 24hours through 144 hours was examined statistically. It was found thatduring this period the increase in the percentage of migrated flies took
place approximately linearly and that there was no significant difference
among the rates per day of migrating flies in four kinds of population
densities. The average increase of migrated flies per day after 24 hours
following the connection with new tubes was 2.25% of the population.
The other experiment was carried out to find out if the mass migration
was dependent on the number of flies present in the original tube. In
this experiment, the migrated flies were counted two days after the connection with new tubes. Data from this experiment are presented inTable 2.
Table 2.

Relation between the percentage of migration andthe number of flies in the original tube.
Initial number of flies in the original tube------;-- -0-50

NO~~:i:n_ei_l_iNo. of migrating flies
(%)

50-99

---------

100-149 I 150-199 I 200-249 I 250-300-:_-_-_-2_-~~~--6-_-_'I_lc-_-_-7-

6

1.89

26.49

2__

5.88

0.65

23.47

I

1---

5- -

24.93

I
!

Table 2 indicates that mass migration of the Samarkand strain of Drosophila melanogaster occurred when the size of the original population
exceeded 150. Thus, in the present experiment, two kinds of migration
were found to occur: one, the so-called "mass migration", which occurs
as the result of pressure of population density, and the other, the so-called "random migration", presumably the result of random movement of
individual flies.

50.

Migration Studies in Several Wild Strains oj
Drosophila melanogaster.

(By Kan-Ichi SAKAI, Takashi NARI'sE and Shinya IYAMA)

Six wild strains of Drosophila melanogaster were collected from different
localities in some parts of Japan. They were propagated as populations
for two generations in the laboratory and were tested for their migrating

RESEARCHES CARRIED OUT IN 1956

74

activity. In the original tube, 80, 120 and 160 flies were placed, and thenumber of migrated flies from the original tube was counted after 2 days.
The experiment was replicated four times. Analysis of variance of data
is presented in Table 1, which shows that local strains are different withregard to migrating activity.
Table 1.

Analysis of variance of number of migrated flies
for three densities of original population.

SourceMean squared.f.

-----~~-----

Population density
Local strains
Density x strain
Replication
Error

308.98*489.31**

2
5
10
3
51

44.46
113.1767.48*, ** Significant at the 5% and the 1% level, respectively.

The percentage of migrated flies in six wild strains is presented in Table
2.
Table 2. Percentage of migrated flies from the original
tubes at three levels of population density.
Migrating activity (%)
Strains
TatebaIguro
Kama
Te-sima
Isima
Katsunuma
+)

80+)

120+)

160+)

Average

39.4
44.3
48.8
50.1
55.6
55.0

40.9
55.3
55.2
59.3
60.7
55.8

42.8
54.7
58.8
57.7
55.7
64.8

41.03
51.43
54.27
55.70
57.33
58.53

The number of flies placed at the start of the experiment in the original
tube: Population density.

The migration in these wild strains was incomparably more active thanin the inbred laboratory strain, Samarkand, in which the migration hardly
occurred unless the number of flies in the original tube exceeded 150.
The next question to be answered was: Is there a threshold in the sizeof population below which the burst of migration rarely occurs? A series

RESEARCHES CARRIED OUT IN 195675

of experiments each with 4 replications were again conducted making thesize of population in the original tube at 10, 20, 40 and 60 flies. Analysis
of variance of the data obtained in these experiments showed that theeffect of population size as well as the effect of interaction between densities and strains were highly significant.
The migration percentage in relation to various sizes of population in
the original tube is graphically illustrated in Fig. 1.
7060"'e::,., 60

...

..,'"
cc
a:: 40
":£

f-

...
0

..,u:z 30f-..,a::"":z 20..,a::

"-

:IE

::>

:z

NUMBER OF FLIES IN THE ORIGINAL TUBE

Fig. 1. Relation between migration percentage and size of population, in one
laboratory stock, Samarkand. and six wild strains.

Fig. 1 shows that the thresholds in the size of population responsible
for the burst of mass migration differ from strain to strain: the criticalsize of population was 60-80 in Tateba- and Kama-strain, 60 in Tesimaand Isima-strain, 40 in Iguro- and Katsunuma-stram.

76

RESEARCHES CARRIED OUT IN 1956

K.

RADIATION GENETICS IN ANIMALS

51.

Effect of External Irradiation with {3-rays upon
the Germ-Cells of the Silkworm(By Yataro TAZIMA)When radioactive phosphorus is administered to the organism, a certain
amount of it might become incorporated as a phosphorus constituent ofchromosomes. The rate of occurrence of chromosome aberrations might
be effectively increased as a consequence of the incessant attack of {3-rays
upon the chromosomes. Therefore, injection of radioactive phosphorus
into the organism might be considered as an effective method for inducing
mutations. However, it would be impossible to relate this effect to theamount of radiation, since the radioactive phosphorus content of the chromosomes is not constant because of metabolic activities which take place inthe course of development. Another difficulty of this method lies is surveying the specific radiation effects at different developmental stages ofof germ-cells, since it is not possible to remove the radioactive phosphorus
at a definite stage of development.
For these reasons, external irradiation with {3-rays of germ-cells ofsilkworm was undertaken in order to estimate the relative sensitivity as
well as mutability at different developmental stages for a definite radiationenergy of a {3-source.
An inbred strain N of Chinese bivoltine race was used in this study.
This strain had the normal alleles for pe and reo Female and/or male germ·
cells of N strain were irradiated by {3-rays at different larval stages of theparents, i.e., fourth stadium, early fifth stadium and late fifth stadium.
A small piece of filter paper which had been immersed in an aqueous
solution of p32- salt and desiccated was used as the {3-source. This piece offilter paper was left pasted for a certain length of time on the dorsal sideof the eighth abdominal segment of a larva, where the gonads are located.
Irradiated individuals were mated to red (re) or double recessives (pe re)after emergence, so that the mutation frequency could be estimated bya study of the frequency of uncoverings at the marked loci. The wild
type, +, for pe (pink) and re (red) is black. Individuals which revealed
themselves as such uncoverings may be regarded as having sustained point
mutations, small deficiencies or gross structural changes. Though it may
not be possible to identify to which type of mutations those changes belong, they may serve as indices to estimate the effect of radiation, i.e.,mutability at specific loci. Sensitivity was estimated by the frequency ofeggs that were left unfertilized or died early after fertilization.

Table 1. pe re (or re) ¥- x treated ~-------.==::...:..::..--==-

Stf~g~ 0 t dparen s rea eYearcontrol

Duration of I Total emission Average numtreatment
fromber of eggs
in hrs.
I
S-source
I laid per mother0 hrs.

1Vth stadium
1955 , early half of theVth stadium
late half ~f theVth stadlUm

118.5

0 MeV.

380.1(25)

3.6%**

9,167

0.00%01.331 x 1010

244.3(24)

28.7

4,180

0.18

97

1.744 x 1010

96

1.440 x 1010

334.0(21)

50.8

3,450

f/

*

f/

f/

79

8.104 x 1010

*

f/

f/

f/

408 9 (20)
.

4 7
.

7 792
,

0 27
.

162 9 (18)
87 0
. .

(f)

0 13

&2

332

0.00

til

':;0
:;0

204.4(16)92.9

376 1(20)
.

21. 2

6 100
0 10
, .

0
0

286.1(11)

17.4

2,647

>-l

0.37

1956 I72

la~t~a;:ad~~~he I

79Ii

8738x1010.
8.104x 1010

'Ii

138 9(22).
602.2(25)* re ¥- x treated ~** Lots with all eggs left unfertilized were excluded from calculation.
number of lots observed.

c:::

Z

treated + ¥- x re ~Table 2.

::r:
tTl

442

--- ---early half of the I
Vth stadium~(J8.738 X 10 10, late half ~f theVth stadlUm

'I

1%6

0.33

__

72

~

(f)

tTl

_______

early half <;Jf theVth stadlUm

Frequency ofdeficient types
per 1010 MeV.
of S-source
per single locus% of unfertiTotal number
lized and early I of fertilized
dying eggs
eggs observed~0>~---1-----;-7~~--1-----0~.

13.3

,"

13,1190.10

Figures in parentheses indicate the

:::l

78

RESEARCHES CARRIED OUT IN 1956

1. 8-irradiation of the male.
The results are set forth in Table 1.
It is noteworthy that the average number of eggs per mother was verysmall in the groups irradiated at the fourth stadium and the frequency ofunfertilized and early dying eggs was very high in groups irradiated at
the first half of the fifth stadium, some of them being totally sterile. On
the contrary, the effect was very small in the groups irradiated at the later
half of the fifth stadium, giving almost the same frequency as the control.
In the fourth and early fifth stadia, the germ-cells remain mostly as
spermatogonia. Meiosis starts after the insect enters into the fifth stadiumand is completed only after the sixth day of the same stadium, provided
that the fifth stadium had covered eight days. In the later half of thefifth stadium, most of the germ-cells are in spermatid and/or spermatozoan
stage. It can, therefore, be said that spermatogonia and spermatocytes
are probably very sensitive to radiation, while spermatids and spermatozoa
are fairly resistant.
There was not much difference between the mutability of marked locibetween spermatogonia, spermatocytes and spermatids.
2. 8-irradiation of the female.
The same trends as above was observed when the female germ-cells
were irradiated (Table 2). The frequency of unfertilized eggs was remarkably high in the group irradiated in the early half of the fifth stadium,
while it was very low in the later half. Also, with regard to the numberof eggs laid per mother there was a marked difference between the early
irradiated (Av. 138.9) and the late irradiated (Av. 602.2) groups.
The oogonial cells multiply rapidly in the ovary during the fourth andearly fifth stadia. Development of oocytes starts at the later fifth stadiumof the parent, and most of them enter into early prophase approximately
at the stage of pupation.
It may be added here that in Drosophila spermatogonia are considered
to be relatively more resistant to radiation than spermatocytes, in contrast
to my results with Bombyx.

52. Genic Control of Xray Sensitivity of Silkworm Germ-Cells(By Yataro TAZIMA)

As was reported earlier, in the silkworm a conspicuous difference is
known to exist in the relative sensitivity of germ-cells to X-rays according
to the strains and to the stage of gametogenesis (TAZIMA and OHTA, 1952;
TAZIMA, 1956). X-ray sensitivity of an "Aka-aka" was relatively higher

79

RESEARCHES CARRIED OUT IN 1956

than that of ad strain (TAZIMA, 1956). Since the former strain is characterized by rb gene and the latter by ad gene, the author undertook an
experiment to find out whether or not the X-ray sensitivity of both thosestrains was influenced by the two genes, rb and od.
After crossing the two strains (ZOdW, +/+-9- xZ+Z+, rb/rb ~)*, four
different combinations for both characters were segregated in F 2 females,
namely od rb (ZOdW, rb/rb) , od+(ZOdW, +/+; 2 ZOdW, +/rb), +rb(Z+W,
rb/rb) and++(Z+W, +/+; 2Z+W, +/rb).
These four different types of females were X-rayed simultaneously withthe same dose, in the same dish, to allow an accurate comparison of theirrespective X-ray sensitivities.
X-irradiation was given at the rate of 83.24 r per minute, in total dosesof 1665, 3330 and 4994 r units. Irradiation was carried out 8 days and18 hrs after mounting, that is on about five day old pupae. The treatedfemales were mated to re or pe re males after emergence. Since all of
the F 2 segregants carried +re gene, F 1 individuals were expected to be
black (+) except for the newly induced mutants at +re locus. By counting the number of red eggs, the mutation frequency could be calculated.
The result is as follows.
Table 1. Irradiation of four kinds of segregating females in F 2
from the cross adxrb (treated + female x untreated re male).
Uncoverings at the re locus- ~~~~~-

----

+

+
ad +

+ rb
ad rb

%
4.2
8.7
8.3
14.0

%

7.5
15.0
11.8
7.9

%
14.2
11.8
26.8
34.8

1665 r3330 r

4994r

%

--%

%

**

0.120±0.042
0.173±0.053
0.308±0.066
0.324 ± 0.090

0.496±0.129 I 0.846±0.166
0.571±0.146 i 1.118±0.271
0.630±0.135 1.142±0.198
0.524±0.019 1.460±0.242* Lots with all eggs left unfertilized were excluded from calculation.
** Standard error.
With regard to unfertilized and early dying eggs, the difference between+ + and od rb it is clear, but it is not certain that such a difference exists
between the + rb and the od +. In general, however, combinations
having rb seem to be much more sensitive than the others. As for muta·
bility, a difference is recognizable between ++ and od rb.
Although not very conclusive, these data appear to suggest that X-ray
sensitivity of germ-cells is controlled to a certain extent by the rb and +alleles.

* ad is a sex-linked gene locating on Z chromosome.

80

RESEARCHES CARRIED OUT IN 1956

53. Chronic Gamma Irradiation of Mice at Different Developmental
Stages and its Effects upon the Breeding Behavior(By Tsutomu SUGAHARA, Kiyosi TUTIKAWA, and Yoshihiko SUGIURA)

A preliminary experiment was arranged for examination of the mutation
rate by the multiple recessive method. Mice were subjected to chronic
gamma irradiation of the entire body at different developmental stages
and the breeding behavior of the treated mice was studied in terms ofmating ability, litter size, sex ratio and abnormal progenies. All irradiations were made from the r-ray source of C06 o, in a specially designed
irradiation room, at a dose rate of 0.36 r per hour, 22 hours per day and5 days per week. A total dose of 450 r was obtained in about 80 days.
The CBA mice undergoing this treatment were kept in aluminum cages.
On completion of the scheduled irradiations, all animals were mated withadult NH mice by placing each male with one or two females for ten
days. During the period of three months animals were remated 3 to 6
times. The treated mice were divided on the basis of their developmental
stages during irradiation into two groups, A and B. Group A consistedof animals receiving radiation from fertilization, through new birth, until
the age of 160 days. Group B was composed entirely of adult animals.
Seventeen males and five females of the first group, and five males andfour females of the second group were studied. The results obtained
are summarized below:(1) Sterility: The percentage of sterility was high for all males in thefirst mating and decreased in the subsequent matings, as in the case of
LAF 1 male mice exposed to a total dose of 1100 r at 8.8 r per day asreported by Lorenz et al (1954). The females of group B, on the contrary,
were all fertile in the first mating and became sterile subsequently. Females of group A were all sterile and no recovery from sterility was observed within a three month period.
(2) Pregnancy with no litter: Nearly half of the females mated with
irradiated males developed the typical changes of vaginal smears anddelivered no litter in the first mating, and some of them behaved likewisein later matings. Presumably this was due to the death of all embryosin the uterus, suggesting the occurrence of clusters of dominant lethal
mutations. As it was very difficult to diagnose pregnancies in the earlystages, cases of pseudopregnancies could not be recognized and eliminated.
For this study, females which had copulation plugs in their vaginal orifices
or showed typical changes of the smear were all considered to be pregnant. It is possible that there were some cases of sterile sperms or oocytes
among them. For the purpose of calculation of mean litter size, the num-

RESEARCHES CARRIED OUT IN 195681

ber of pregnant females instead of that of litters born was used as acorrected estimate.
(3) Mean litter size: (Table 1) Quantitative comparison of the litter
size from irradiated males suggested that group A corresponded roughly
to a single X-ray dose of 300 r, and group B to that of 600 r. As forirradiated females group A was more heavily damaged than group B.
(4) Sex ratio: (Table 2 and 3) In the case of irradiated males of groupA a statistically significant increase occurred in the proportion of males
in their progeny. This increase in the frequency of males was graduallymore pronounced from matings one month after the irradiation onwards.
(5) Abnormal progenies: Recessive mutations at three loci of doubleTable 1. Mean litter size.
Order of mating

lIst

I

,

2nd ! 3rd 14th

5th

i

i

6th

Total

No. of mean
2.9 litters litter size

I
I,-------,--'--,-----.

Months after irradiation i 0.4
I0.9

1.4, 1. 9

2.4'

i maleI a
I
4.6
6.2 i 5.7 i 5.8
6.7 i 4.6
42
irradiated 1 - - - · - - , - - ' - · - - - - - - - - - · - - - -!

Group A female:

1~~3J :.9! :.3,_:.~--:.~1 :.6 ~i irradiatedb0-----,
I

male
i irradiatedI

Group B i';~:a~~'___ ~adiated

0
----,

O.

0

i

0

---_.,---

0

5.66
4.76

I

- ---_.,-_ .. _-3 .1_:~.3_
3-:<lI-i;- 2.69

a
0 I 6.0 I'. 7..0. " 2,.5
6.0' 3.0"
b -0-!6.0-,-';:;I-Z-:-sT6:0T
i,

I'

a-T'-

[6~2-i-4.0--!--=-13.0r 9 _!~5.66-~i,__6·:~_~~,i~'_5~_.

Control non-irradiated

7.33

7

a) Litter size per born litter.
b) Litter size per pregnant.
Table 2. Sex ratio (males/females).
No. of
F 1 micemale irradiatedGroup-A female irradiatedmale irradiatedGroup-B female irradiatedControl

238
0
35
51
52

!

Sex ratio

Statistical significanceof the difference from
1:1 ratio (p=0.05)

1.67

+

1.91
1.21
1.36

82

RESEARCHES CARRIED OUT IN 1956

recessive NH mice were not observed in Fl, which is only to be expectedin view of the small size of the population (total 268 mice). Seven micedied within thirty days, and one of them was small and had a short andnicked tail.
The irradiated males and females appeared to differ in their breeding
behavior. Females were more sensitive than males. The radiosensitivityof the reproductive organs in the embryonic and very young males appeared to be quite low compared with that of the adult males.
Table 3.

Sex ratios of successive litters of the group A males.

Order of mating

1

2

3

4

5

6

----

Months after irradiation
Age at mating (in months)
No. of F 1 miceSex ratio

54.

0.4
2.4

0.9
2.9

1.4
3.4

14

31

0.4

1.2

40
1.1

1.9
3.9

!
I

41

2.4
4.4
67

2.9
4.9
23

1.9

2.0

2.8

Radiosensitivity of Various Mice Strains(By Tsutomu SUGAHARA, Yosihiko SUGIURA and Tetsuaki HASIMOTO)

The differential response of various strains of mice to a single X-ray
dose was studied by observing the number of days of survival after
a lethal dose. The survival curves showed a few characteristic peaks
which corresponded to the modes of lethal effects. A relative small number of animals and a short observation period were found to be sufficient,
Table 1.

Mean survival of various mice strains exposed to a single
X-irradiation of 1,000 r.
--

StrainSex_ _ _ _ _ _ _ _ _ _ _ _--,'-CBA
C57BL
C58

SPS
hy x C 57 BL-F2

No. of animals
t_ested
7
5
8
5
12
7
29
29
7

7

!

-

Mean days survival(95% rangeL_ _3.36±0.206
8.00±1.449
4.50±1.262
4.60±2.421
7.17 ±1.915
7.55±0.872
6.93±0.620
6.69±0.781
6.57±1.285
8.43± 1.177

RESEARCHES CARRIED OUT IN 195683

as compared with the number of animals and the period of observation
used in the conventional measurement of LD 50 for 30 days.
The irradiations were made as follows: the mice were placed in hollow
cylinders of acrylate resin which were fixed radially on a rotating disc.
The animals were irradiated with a single dose of 1000 r delivered at therate of 20.3 r/min. in air at the distance of 47 em. from the target (160 KVP
X-ray, 3 ma curr., 2 mm Al filter). The animals tested were six to twelve
months old.
No correlation was found between length of survival and body weightat the time of irradiation. The frequency curve of survival days for both
sexes had two peaks, at the fourth and at the eighth day, and was significantly different from the normal distribution. With reference to the sexes,
for males the peak at the fourth day was higher than at the eighth day,and the reverse was true for the females. The differences in the mean
number of survival days between males and females and between various
strains were statistically significant, as shown in Table 1. In general, thefemales were more radioresistant than the males.

55.

The Effects of X-Irradiation on Nitrogen Metabolism
in Drosophila melanogaster(By Toshifumi TAIRA and Saburo NAWA)

Only a few studies have been reported on the effects of X-irradiation
upon the metabolism of Drosophila. When the larvae of Drosophila areirradiated with either X- or r-rays, melanotic tumors are often found in
addition to other morphological abnormalities. Their incidence, however,differs among genotypes and varies according to environmental conditions.
Both sed and cn;ca among the eye-color mutants seem to have rather
a higher incidence of melanotic tumors than the others under the sameenvironmental conditions.
After irradiation of second-instar larvae of sed, grown on normal medium,with X-rays (160 KVP, 3 mA) of 1,000 r, a delay in pupation was foundthough the treated larvae were not all killed. Those pupae showed avacuole during metamorphosis, and no flies hatched from them. Larvae
with melanotic tumors often could not go through normal pupation. Prepupae, therefore, were used as materials employed for spectro-photometricalmeasurements of the quantity of uric acid by means of degradation withuricase. The results are shown in Table 1.
The examination of melanotic tumors by roentgen-photography, revealed
that the tumors showed a reduced X-ray absorption in comparison withRESEARCHES CARRIED OUT IN 1956

84

Table 1. Microdetermination of uric acid in prepupae of sed strainof Drosophila malanogaster.
Plots

Uric
I

Acid

(r/mg)

II

III

Mean

Control(Non-irradiation)
Irradiated Without
Melanotic Tumors
Irradiated With
Melanotic Tumors

4.16

4.04

3.78

4.0

±

0.13

3.78

3.72

3.38

3.6

±

0.15

2.79

2.88

2.37

2.7

±

0.19

Standard
Deviationother parts of the body_
From these results, we may reach the following conclusions:(a) The quantity of uric acid in Drosophila pupae decreases significantly
after irradiation.
(b) The quantity of uric acid is apparently smaller in the pupae withmelanotic tumors than in those without tumors.
(c) Since the decrease of uric acid suggests a decline of nitrogen metabolism, it may be said that irradiation causes an abnormal state in nitrogenmetabolism which brings about melanotic tumors and finally death of theaffected animals.

L.

RADIATION GENETICS IN PLANTS

56. Genetic Effects of Ionizing Radiation in Einkorn Wheat(By Seiji MATSUMURA and Taro FUJII)

Dormant seeds of Triticum monococcum var. fiavescens were exposed to
X-rays, r-rays and fast neutrons.
X-rays of different wave lengths at the same dosage (10 Kr) and intensity (82 r/min) were used with different filters; also the effect of r-radiation by COBO was examined for comparison. The thickness of the filter
was adjusted in inverse proportion to the wave length; that is, at 100 KVP
a filter of 2 mm AI, and at 180 KVP one of 0.8 mm Cu + 1.5 mm Al wasinserted into MATSUDA'S Type KXC-17 apparatus. At 50 KVP and 20 KVP,
irradiation was applied by two other types, Modified Type KR-75 andType TX-20 (Grenz-rays) without filter, respectively. The data are shownin Table 1.
There was no striking difference between hard and soft X-radiation, in

RESEARCHES CARRIED OUT IN 1956
Table 1.

85

Relation between wave length of X- or r-rays and frequency ofchromosome aberrations in Triticum mO'TIococcum.

_.-.~--------=-====== ~===

DosageVoltage

(Kr)

(KVP)

ch~omo-I

p~~~~-

"

(%)

. IL
th 1Ft'Chloro-IIer~Tl1- I eng
I . er 1some
phyll
nies
nation 10f seed- hty of ab a I
ta' 'thout
ratelings* 'spike in . err. - I?u.- I WI.
(cmi I. X (0/) tlOn In tIon In. I ger~Tl1( %)
o
.
.
I
/0
Xl (%) I X 2 (%) nation

G

I'

ControlI

10 (82 rJmin) I"(82 ,,) i" (81.4 "

20
50
100
(with filter 2 AI)
180" (81.2 "(with filter
0.8 Cu+1.5 AI)
r-ray
5 ( 8.3 " ) I
10 (16.6 " )"15 (25
"
) I
"
10 Ah
Neutron (4-7 MeV)
9
(10 neutron/A. sec)
15 Ah
I
"
20 Ah
I,

92.00 I 17.44(14.54)82.00 I 15.85
14.23
88.00
60.00
10.20

44.20
40.73
32.33

90.00

11.11

0.00 I

0.0

0.0

4.88
10.81

6.3
6.8
8.3

3.0
4.8
7.7

36.50

21.82

10.3

8.1

13.93
38.00 I 12.73
50.00 . 8.96
98.00 (14.25)

62.95
38.72
32.18

1.67
5.56
6.25
1.33

4.8
2.2
0.0
1.2

88.00 (14.53)
79.59 I (13.84)1

37.01
27.66

4.17
4.55

3.7
2.7

92.00

60.45

I

54.20

12.50 I

I
Ii

'

1.2
0.0
5.1
2.4
1.2
6.3

"

* X- and r-irradiated seeds were sown November 9th and the seedlings were
measured 26 days after sowing. () Sown December 12th and measured 26days after sowing.

so far as the germination of seeds is concerned, but the growth of seedlings showed a slight delay with the decrease of wave length. The higher
the dosage of r-rays or neutrons, the lower was the germination rate ofirradiated seeds, and the more delayed were the germination of seeds andgrowth of seedlings. It was shown, in terms of growth inhibition of theseedlings, that neutrons with a high specific ionization more uniformly
affect the irradiated seeds than X- and r-radiations with a low specificionization.
The mean single-spike fertility of X-rayed plants generally decreased
with the decrease of wave length. This relation is in good accord withthat between the growth of seedlings and wave length. Also, the relation
between the rate of induced sterility and wave length coincides roughlywith the relation between the frequency of chromosome aberrations orchlorophyll mutations and wave length. But at 20 KVP the aberration
frequency was unexpectedly high, while at 50 KVP it was too low.

86

RESEARCHES CARRIED OUT IN 1956

It was also ascertained, as expected, that mean fertility decreased withdecreasing germination rate accompanied by weaker growth of seedlings,
and the chromosome aberrations increased in proportion to the dosage of
r-rays and neutrons. Concerning the frequency of gene mutations in X2 ,the head progenies which did not germinate at all, must be added to thechlorophyll mutations.

57.

Effects of X- and r-radiations upon Wheat Seedlings and Their
Modification Due to Temperature or Polyploidy(By Seiji MATSUMURA, Taro FUJII and Sohei KONDO)

Dormant seeds of Triticum monococcum were subjected to X- and r-ray
treatments at the dosage 10 and 20 Kr. The germination rate of treatedseeds and the growth of seedlings were compared for acute and chronic
irradiation. In the former X- and r-irradiation was applied either immediately before sowing or the irradiated seeds were kept for 30 days instorage and in the latter r-irradiation lasted 54 days. In one experimentwith acute irradiation one part of the treated seeds were kept at room
temperature (about 20°C) and the remainder at low temperature (5~C) for
30 days.
There was no marked difference in germination rate between untreated
and treated seeds at 10 Kr, while the germination rate was reduced to
1/2-2/3 at 20 Kr. In the case of 30 day storage, r-rays inhibited thegrowth of seedlings more than X-rays, while the irradiation applied justbefore sowing showed the reverse relation. It was found further especially with r-rays that low temperature was more effective in inhibiting
growth than room temperature. At 10 Kr, the acute r-irradiation was
more effective in this respect than the chronic one. On the other hand,
the reverse relation between acute and chronic r-irradiation was observed.
To examine the relation between the sensitivity to ionizing radiationand polyploidy, dormant seeds of Triticum monococcum (2x), T. durum(4x) and T. vulgare (6x) were exposed to X- and r-rays at the dosage 1040 Kr. In general, r-irradiation had a markedly stronger inhibiting effectupon seed germination and seedling growth than X-irradiation. 2x was
most sensitive to X- and r-rays and 6x was most resistant. There was
unexpectedly no significant difference between 4x and 6x.

87

RESEARCHES CARRIED OUT IN 1956

58. Mutants in Tobacco Plants Induced by X-rays andTheir Application(By Seiji MATSUMURA and Taro FUJII)

Dormant seeds of the variety Bright Yellow (in 1955) and its mutant" early" (in 1956) were exposed to the same dosage (30,000 r) of soft andhard X-rays with varying kilovoltages. The germination rate of treatedseeds generally decreased with the increase of kilovoltage. Namely, it
was 66.5, 47.8 and 25.5% at 20, 50 and 100 KVP respectively in 1956, whilethat of untreated seeds was 69.0%. Many recessive mutants were observed in the X2 -generation of Bright Yellow, such as narrow, oblongleaves, dwarf, etc.
The mode of inheritance of many mutants obtained in the previous experiments was investigated in the Xg-X 6 generations of Bright Yellow and
Dixie Bright 101.
"Early" (No.6) and" pubescent" (No. 12), mutants of Bright Yellow,
appeared after a 10,800 r-irradiation at 90 KVP in one of the earliest experiments (1950). Their leaves, as well as those of "yellowish green"(No. 13) derived from 50,000 r-irradiation at 180 KVP (1951) of Bright
Table 1.

Yield in Kg. and value in Yen of leaves of X-ray mutants offlue-cured tobacco. (1956)--------- ...- -Strains!

I

I

per Tan*per Kg.

Average
grade

17.6
17.2
17.4
16.5
17.9
15.4
15.8
15.9

134
129
135
153
132
133
180
176

303
276
344
294
339
257
277
256

3.78
4.32
3.10
3.92
3.17
4.55
4.21
4.56

40,46935,52846,33045,15844,90334,061
49,99445,172

17.0
16.9

170
178

222
268

5.14
4.35

37,75347,741

16.8
18.2

153
159

241
303

4.91
3.77

36,86048,386% of dry IYield in Kg.Value in Yen

matterReturn per
ITan* in Yen

I-,-------",-'._----

Bright Yellow

6-2-1
6-2-2
6-3
12-2
13-1
13-2
19 (the same strain
as No. 13)
20 (Dixie Bright)
23 (the same strain
as No. 20)2122 (D. B. x X-rayed
B. Y.)--------* Tan=ca. 0.1 ha.

88

RESEARCHES CARRIED OUT IN 1956

Yellow, seem to be of good quality (Table 1). These mutants may prove
to be useful for the improvement of tobacco and in 1957 comparative experiments with these mutant strains will be carried out on a large scalein various districts.
The" round leaf" mutants derived from 30,000 r-irradiation at 180 KVP
of Dixie Bright 101 (Nos. 20 and 21) (1953), and the" broad leaf" mutants
observed in the offspring of Dixie Bright pollinated with irradiated pollen(290 r, 50 KVP) of Bright Yellow (No. 22) (1953) showed a pronounced
resistance against white fleck.

59. Studies on Chlorophyll Mutants in DiPloid Wheat
Induced by Radiation(By Taro FUJII)

Further studies on several mutant strains of Triticum monococcum var.
flavescens induced by X-rays, were made.
The mutant strains "chlorina" (light green leaves) and "basi-viridis
II" (base of leaves yellowish green) were crossed in 1955. All the F 1 plantsfrom this cross were morphologically normal, and showed high germinating capacity and high seed fertility. In the F 2 generation, chlorina andbasi-viridis II were found to be controlled independently by a recessive
gene each, and a segregation according to the dihybrid ratio was observed.
The chlorophyll content in both parents amounted to about 50% of thatof the normal plants, but when basi-viridis II was illuminated by fluorescent lamps (about 4,000 luxes) in the dark phytotron (20°C), this mutant
gradually recovered the green coloring and its chlorophyll content reachedthat of the normal plants, while in the chlorina mutant such a marked
recovery of chlorophyll was not found. The chlorophyll content of the
double-recessive plants grown in the field was about 20% of the normal
and a high degree of mortality was observed. When these plants weregrown in the phytotron, their leaves gradually became light green, andtheir chlorophyll content was restored to the chlorina level but further
recovery did not occur. It is possible that the chlorina gene is epistatic
over the basi-viridis II gene.
In 1956, crosses virido-albina x basi-viridis II (both parents have theability to recover the chlorophyll content), virido-albina x chlorina, andchlorina x striata (neither has the ability to recover) were made. It was
found from these experiments that these characters might be controlled
by different genes, as all of the F 1 plants were normally green.
In 1955, X-rays were applied again to two mutant strains (chlorina andRESEARCHES CARRIED OUT IN 1956

89

slender) which had been induced by X irradiation. Results of these experiment are shown in Table 1. The percentage of chromosome aberraTable 1.

Effects of X-irradiation on Einkorn wheat and its mutants.

I £mog,St,,;,

u~~~:+;,r~ii~l~~~t;~

Averagefertility
in Xl (%)

1--:-~~I--~:----il~~~~·~I~~:~~- ~.0---'--:-:-:-~~1~~:~~1

Normal10 Kr
15 Kr
Chlorina
5 Kr
10 Kr
15 Kr
Slender
5 Kr
10 Kr
15 Kr

88104.5( 94.1)
78
1,101.8(100.0)0
3.1

36.7( 41.2)j
27.5( 30.9)i

194.8(100.0)807887.9( 92.7)
I
66
89.3( 94.2)
7676.9( 81.1)' 97.1(100.0)
98
96106.5(109.7)
72
101.5(104.5)

0
5.6
17.9
0
2.2
8.3

68.1(100.0)
34.4( 50.5)
20.1( 29.5)
1O.1( 14.8)
47.8(100.0)
55.2(115.5)
49.7(103.9)

76

9.1

25.0( 52.3)1

93.1( 95.9)%of chrorophyllmutation
in X2

o
7.8
7.9

o
o
o
o
14.3

o
3.6
1.6
6.3

tions in Xl and that of chlorophyll mutations in X2 were higher than in
the normal plants. Further, the chlorina strain showed in Xl more clearly
than the normal plants a marked decrease in the average fertility with
the increase of dosage. On the other hand, the slender mutant did notshow these trends. This might be due to genotypic differences in thesusceptibility to X-rays.

M.

60.

GENETICS AND CYTOLOGY OF MICROORGANISMS
AND VIRUSES
Transductional Analysis of Phase Variation in Salmonella(By Tetsuo IINO and Joshua LEDERBERG*).The flagellar antigens of Salmonella can be dIvided into two groups,
viz., phase-l: a, b, C, etc., and phase-2: 1.2, 1.5, enx, etc. Cultures of diphasic salmonella strains are composed of two types of cells. One type*

Department of Genetics, University of Wisconsin, Madison, Wis., U.S.A.

RESEARCHES CARRIED OUT IN 1956

90

manifests an antigen in phase-I, and another in phase-2. The variationfrom one phase to another may occur at the frequencies of 10- 3 to 10-5
per cell per division depending on the strains (STOCKER, 1949). This phenomenon is called phase variation. For the genetic analysis of the phenomenon, transduction _was used to achieve recombination of antigenic
factors.
Lysates obtained from Salmonella typhimurium TM2 culture, which has"i" antigen as phase-l and "1.2" as phase-2 (This is decribed as i:1.2),
were mixed with cultures of S. abony CDC-I03 (b:enx). The mixtures
were cultured on semi-solid media containing anti-b and anti-enx serums.
The swarms developed from these cultures, which are expected to haveflagellar antigen other than band enx as a result of transduction. haveantigenic composition b: 1.2 or i:enx, but never i:b, 1.2:enx or i: 1.2. This
result indicates that the antigenic specificities of phase-l and phase-2 arecontrolled by independent loci in each, which will be symbolized by HI
and Hz. Transductional experiments in reverse directions and between
different strains proved the generality of this conclusion and led to theestablishment of two series of multiple alleles of HI and Hz. Therefore,
flagellar antigen genotypes for each phase are HIa, HIb, HI", etc. and
HzI.z, H z!.5, Hzen z , etc. respectively.
Next the same experiment is done with a single phase culture in whichmore than 90% of the cells are in one phase (Antigen of the predominant
phase is described with under line). Then, different transductions arerecovered in different frequencies depending on the combination of thephase of donor and recipient as follows:
Donor
RecipientTransductions i:enx
recoveredb: 1.2i: 1.2b:enx
39
1

i: 1.2b:enx
3
0

i: 1.2b:enx
23
23

i: 1.2b:enx
321

As it is clear from this table, frequent transductions of HIt are recovered
when the recipient is phase-l regardless of the phase of donor, whereastransductions of Hz!.z are recovered only when donor is phase-2 on any
recipient. The parallel results were obtained in the reverse transduction(transduction from S. abony to S. typhimurium). The few exceptions observed are assumed to be due to the cells of alternate phase which havebeen mixed at the proportion of lower than 10%. As HI and Hz aretransduced independently and the efficiencies of transduction do not differ
markedly. HI-transduction and Hz-transductions are produced in every
combination of phases. However, anti-b and anti-enx serums were contained in the media for selection, and they suppressed the development

RESEARCHES CARRIED OUT IN 1956

91

of transductions i:enx and E:1.2, which could not express transduced antigen types immediately. The difference of the result in different phasecombinations may be explained by the non-recovery of such fractions oftransductions. Consequently, it is concluded that HI can be expressed
only when transduced into phase-l cells regardless of the phase of donor,
whereas H 2 can be expressed in any phase of recipient but only whendonor is phase 2.
From these results, the following hypothesis is proposed: "H2 can taketwo different states, active and inactive. Active H 2 inhibits the phase-l
antigen production, specified by HI, and controls the production of thespecific phase-2 antigen. When H 2 changes to the inactive state, whichcorresponds to the change from phase-2 to phase-I, the production ofphase-2 antigen stops and alternatively the production of phase-l antigen,specified by HI, proceeds."

61.

Electron Microscopy of Thin-Sectioned Nuclei in Paramecium(By Mitsuo TSUJITA, Kyozo WATANABE and Seizo TSUDA)

The inner minute structure of the nuclei of Paramecium is not yet wellknown. Recently the structure of the nuclei in Ciliatae as revealed byelectron microscopy has received considerable attention. BREITSCHNEIDER(1950), FINLEY (1951), SONNEBORN (1953), TSUJITA, WATANABE and TSUDA(1952, 1954) and EHRET and POWERS (1954, 1955) have studied the fine structure of the macronucleus by electron microscope.
The present paper deals with some additional information on the finestructure of the nuclei of Paramecium caudatum observed in ultra-thinsections. A clonal culture of Paramecium caudatum, which originatedfrom one individual, was employed.
The macronucleus of P. caudatum is surrounded by a thin nuclear membrane. Inside numerous minute particles, spherical or oval in shape whichsometimes look like beads appear connected by fine strands. These particles measure about 0.1-0.2 flo in diameter. The bead-like structures are
distributed throughout the whole macronucleus. Spherical granules whichmeasure 0.4 flo or more in diameter are scattered here and there. They
are often observed in abundance at the periphery of the nucleus.
From methyl-green pyronin staining of the materials fixed by alcohol
it is evident that these granules take pyronin dyes. From this fact it
may be inferred that they are nucleoli.
Although we can easily observe the inner structure of the macronucleus,
it is difficult to get a good view of the inner structure of the micronuc-

92

RESEARCHES CARRIED OUT IN 1956

Ieus because the latter is much smaller. The micronucleus is also surrounded by a thin nuclear membrane which shows almost the same appearance as that of the macronucleus. As seen from the figure, in theright part of the section of the micronucleus appear entangled filamentous
bodies, while in the other part globular particles connected by strands canbe seen, some of the latter looking like thick fibers or spiral structures.
The inner structure of the micronucleus somewhat resembles a prophaseof cell division in higher organisms; however whether it is a true prophase is uncertain. To clarify this point further studies are required.
In the micronucleus we cannot see nucleolar granules as observed in themacronucleus.

Fig. 1.

Electron micrograph of a thin section of a macronucleus of ParameIn the concavity of a macronucleus, a micronucleus can be seen.
x 9,000.

cium.

There are several reports on the fine structure of the nucleus of Paramecium. BREITSCHNEIDER (1950) observed in the macronucleus of P. caudatum by electron microscopy many irregular spherical bodies connectedby thin strands, and fewer larger bodies. He interpreted the former as
chromosomes, and the latter as nucleoli. But no proof was offered of thecorrectness of this view. According to KIMBALL'S cytological observations
by phase contrast microscope, the macronucleus of Paramecium contains
two types of bodies, namely spherical granules which are scattered moreor less at random and many fine filaments almost completely filling out

93

RESEARCHES CARRIED OUT IN 1956

the nucleus. SONNEBORN (1953) reported also that there are two kinds ofgranules in the macronucleus.
In our preparations many globular particles connected by fine strands
or bead-like structures could be observed in the macronucleus. From thefact that these substances show positive reaction to Feulgen and that they
stain with methylgreen by methylgreen-pironin-staining method, it may
be said that these structures have some relation to chromosomes. The
bead-like structures somewhat resemble spirals.
In our previous paper we have suggested that there may be some relation between the nucleoli of the macronuleus and the granules in thecytoplasm. Recently this point has been also discussed in detail by EHRETand POWERS (1955).

N.
62.

MATHEMATICAL GENETICS

Random Genetic Drift in a Tri-allelic Locus; Exact Solution witha Continuous Model(By Motoo KIMURA)

In the last report the author presented the exact solution of the processof random genetic drift in a locus with a pair of alleles. The details
have been published in Proc. Nat. Acad. Sci. (Vol. 41). Also the asymptotic solution has been worked out for a multi-allelic locus by studying
the process of change in the moments of distribution. The detailed reo
suIts have been published in Evolution (Vol. 9). Recently the author succeeded in obtaining the exact solution for the case of three alleles basedon a continuous model and the partial differential equation method.
Consider a random mating population of N breeding individuals and let
AI, A 2 and A 3 be the three alleles whose respective frequencies in the
population are x, y and z (x+y+z=l). If we denote by ¢(x, yiP, q;t) the
probability density that the frequencies of Al and A 2 are respectively
x~x+dx and y~y+dy in the t-th generation, given that their initial frequencies are P and q at t=O, then it is possible to show that ¢ satisfies
the following partial differential equation:a¢at

1 8 2 {x(l-x)¢}- L __~"-{xy¢}+ _1__ ~2.{y(1_Y)¢} .
2N 8x8y
4N 8y2
4N 8x 2(0 <x <x+y 1)<

The required solution satisfying the initial condition¢(x, YIP, q, O)=o(x-P)·o(x-q)

94

RESEARCHES CARRIED OUT IN 1956

has been published in "Biometrics". The probability distribution of genefrequencies in the unfixed classes where all the three alleles coexist indicates that the distribution surface finally becomes flat and decreases inheight at the rate of 3j2N per generation as opposed to 1j2N for a pairof alleles. (d. Kimura, M. 1956. Biometrics 12: 57-66.)

63.

Selection in a Finite Population (Case of Complete Dominance)(By Motoo KIMURA)

Studies of interaction between natural selection and random genetic
drift should be important in evolutionary genetics. In the last report thepresent author discussed the process of genic selection (case of no dominance) in a finite population using the partial differential equation method
and showed how the exact solution could be constructed in terms of theoblate spheroidal wave function. Very often, however, there is some dominance between alleles, and usually "complete dominance". In what
follows new results obtained for the case of complete dominance will bereported.
Consider a random mating population of N breeding individuals. Suppose that the gene A is completely dominant over its allele A' and thedominants AA and AA' have selective advantage s, measured in MALTHUSIAN parameters, over the homozygous recessive (A' A'). If we denoteby ¢J(xIP;t) the probability density that the frequency of A lies between
x and x+dx in the t-th generation given that it is p at t=O, then 1> satisfies the following partial differential equation:~;=-/ii :;,{x(l-x)¢J}- ~-{s."C(1-x)21>}.
For a small value of Ns we can expand the eigenvalues into power seriesof Ns. The most important information is the smallest eigenvalue (A o)given by the series
2NAo=1- 1 - c+_I~-c2+ 1L c3_ 23·41·29599 c1 •••5
2.5 3 ·7
2.55 ·7
23 .33 .5 6 .7 3 • II
where c=Ns. Here Ao gives the ultimate rate of decrease of the probability that A and A' coexist in the population, namely the rate of decay.
The most remarkable fact suggested by the present analysis is that ascompared with the case of pure random drift, selection toward dominants(s> 0) decreases the final rate of decay, while selection against dominants(s 0) increases it. The detailed study of this problem together withdiscussions of other topics will be published in Ann. Math. Stat.

<RESEARCHES CARRIED OUT IN 1956

95

64. Probability Distribution of Gene Frequencies in
Natural Populations(By Motoo KIMURA)

In 1938 WRIGHT published a formula for the probability distribution ofgene frequencies at the steady state, which may be written in the following form.

where x is the gene frequency, and Ms x and VSx are respectively themean and the variance of the rate of change in x per generation. As
far as one locus with a pair of alleles is concerned the formula is quite
general and it may be regarded as one of the most important formulasin population genetics.
In the evolution of species, however, genic interactions may be quite
important and hence extension of WRIGHT'S formula to cover multi-variate
cases should be required.
Let us consider a bivariate case with two random variables x and y on
which no constraints are imposed. Thus x and y may represent the frequencies of any two alleles in the case of a single locus with three allelesor the frequencies of any two non-allelic genes in the case of two locieach with a pair of alleles. We shall designate by ¢(x, y) the probability
density of x and y at the steady state, and by Ms x ' Ms y, VSx' VS y andWSxs y the means, the variances and the covariance of ox and oy.
Then
we obtain the following theorem: If the simultaneous linear equationsin ejJ", and ejJy{
have a unique and non-trivial set of solutions (ejJ"" ejJy) and if

is an exact differential, which we write as dejJ, then the steady state distribution is given by ¢(x, y)=Ce'i', where C is a constant determined by
the conditionH¢dxdy= 1 (terminal classes excluded).

96

RESEARCHES CARRIED OUT IN 1956

The theorem can be extended to cover multivariate cases in general.
As an application of the theorem or of its extended form, it is possible
to give a rigorous poof of the simultaneous distribution of gene frequencies obtained by WRIGHT (1949):
l;¢(Xl' X2, ••• , X'k) = Cli 2N ll Xi4.zrmxi-l ,I-I

in which m is the rate of migration and Xi is the frequency of the i-thallele in the migrants.

65.

The Rate of Change of Population Fitness by Natural Selection(By Motoo KIMURA)

R. A. FISHER'S" fundamental theorem of natural selection" states that therate of increase of the average fitness (a) of a population (measured in
MALTHUSIAN parameters) is equal to its genic or additive genetic variancein fitness (Vu) at that time, namely
dri
dt = V,.

Since the variance is a non-negative quantity, the fitness in relation to a
fixed external environment always tends to increase. The formulation
seems to be compatible with the general picture of evolution in the pastand may be considered as a quantitative description of an essential feature of evolution.
However, in addition to increases in population fitness attributable tochange in gene frequencies, the average fitness may be altered by suchthings as changes in the mating system when dominance or epistatic factors are involved, or changes in the relative fitness of individual genotypes.
Thus with one locus segregating we have
dri = V u+ ~'" p ij datj"'P U d U -d Iog {} ij--d--d-- +,L,
t
ij
t
ij
dt

or more concisely(O""'d log (}jdt)

where {}lj=PijjXiXj, Xi is the relative frequency of the i-th allele Ai, Plj
is the frequency of AlA j and du is the dominance deviation of au (fitness
of AiAj) from additivity.

RESEARCHES CARRIED OUT IN 1956

97

With an arbitrary number of loci each with arbitrary number of alleles
the corresponding formula is(!P==d log cp/dt)
where c is the deviation from additivity due to dominance or epistasis
and cp is defined as the ratio of the actual frequency of a genotype to thefrequency expected from random combination between alleles (in the caseof dominance) or between loci (in the case of epistasis). The summation
is over all relevant loci.
Thus the rate of increase of population fitness by natural selection isexpressed as a sum of the three terms: A term due to additive genetic
variance, one due to average increase of individual fitness of genotypes.. and one due to the joint effect of genetic interaction and change in mating
system.

66.

A Model of a Genetic System Which Leads to Closer Linkage
by Natural Selection(By Motoo KIMURA)

At the 1955 Cold Spring Harbor Symposium (XX: Population Genetics),
Dr. P. M. SHEPPARD proposed the following problem for mathematicalanalysis: Assume a locus with a pair of alleles, say Al and A 2 , kept inbalanced polymorphism by heterozygote superiority in fitness. Anotherpair of alleles, B I and B 2 , are at another locus on the same chromosome,and interact with the genes in the first locus in such a way that Al isadvantageous in combination with B I but is disadvantageous in combination with B.J , while the situation is reversed for the gene A 2 • Then thesecond locus will remain polymorphic if linkage between the two loci issufficiently close. Under this model, close linkage would maintain a larger fraction of the fitter genotypes than loose linkage and an inversion
or other crossover reducing mechanism will be favoured by selection.
The present author carried out mathematical analysis of this problem
and has succeeded in confirming SHEPPARD'S view in quantitative terms.
(ct. KIMURA, M. 1956. Evolution 10: 278-287.)

98

RESEARCHES CARRIED OUT IN 1956

O.
67.

TECHNICAL NOTES

Dosimetry of Gamma Rays with Glass(By Sohei KONDO)

It is well known that glass usually takes a brown or violet color whenirradiated by ionizing radiations. According to the modern view, thecoloration is, as in the case of alkali halides, ascribed to electrons trapped
at negative ion vacancies or at other defects present inside the glass.
For the present treatment, however, the nature of those centers is of noimportance; we may assume that there are a certain number of colorable
centers due to imperfections and that the electrons freed by irradiation
can be bound to them to form colored centers.
Let us take N as the total number of the colorable centers per unit
volume in glass, n as the number density of colored centers due to irradiation by r rontgen. Then, it may be assumed, as in the case of LEA'S
hit theory, that the increase in the colored centers, dn, due to an infinitesimal increase dr, is proportional to the number of uncolored centers:
dnjdr=a(N-n) ,(1)

where a is a constant.
On the other hand, the light absorption coefficient of glass, p, is proportional to the concentration of colored centers n. Hence from (1) we
obtain(2 )where p~ is the saturation value of p.
equation (2) reduces to

In the low dosage limit of r,(low dosage limit)(3)This means that the color intensity of glass induced by irradiation is
proportional to the dose of radiation so long as the dose is not very high.
The relation (3) is well represented in Fig. 1. Furthermore, the remarkable homogeneity of glass is shown in Fig. 2 where the maximum (notthe standard) deviation is given. Thus, we may conclude that even asmall piece of glass can serve as a very accurate dosimeter.
There is, however, a defect, and that is the bleaching of the induced
color occurring spontaneously even at room temperature, further accelerated by heat and visible light. Therefore, the linearity between the..

RESEARCHES CARRIED OUT IN 1956

99

f: a.bsorp,t.:.olt coeffiCi&71t
e,;;'

(().t

4::tO 7rt.1"- )
El

~.5

.2.0

Fig. 1. An example of thelinear increase in the induced absorption coefficient of glass with increasing doses of gamma raysdelivered for the same
duration of time.

1.5

1.0
El

consta.nt j,rrM,ition ti?!l&0.5( ~O ~ ... )o_~---&-<:> 0Gl0d'/fere1l.l

.;

~OO

IlrO

_COltSJ;...

C!)..

mea", ...t..."
05+ tOOl

IDOD

Fig. 2. Homogeneity ofglass with respect to itschange in the absorption
coefficient due to gamma
rays as seen from values
for glass pieces sampledfrom the same glass plate.

spec~mtns

Fig. 3. A curve showing
the non-linear increase in
the absorption coefficientof glass with increasing
doses of gamma rays delivered at a constantrate. (Compare with alinear increase line - - - -.).t dC>e r. te. ( 10 "r/#. .. )

100

Kr

IDDOD /'Ir

RESEARCHES CARRIED OUT IN 1956

100

color intensity and the radiation dose can be observed only under constantirradiation time but not under constant dose rate of irradiation (see Fig. 3
in log-log scale). This bleaching effect is now under investigation with'a view to making possible the use of glass dosimeters, accurate up to one
percent in measuring errors.

68.

Thermodynamical Fundamental Equation forSpherical Interface*(By Sohei KONDO)

The relation between the radius of the Gibbs dividing surface, a, andsuperficial density was investigated in detail and the generalized Kelvinrelation was obtained. Consequently the fundamental equation for spherical interface is expressed by

dE= TdS+J1.dN-Pf1,dVf1,-Pf3dVf3+rdA+(8r/8a)Ada ,where the last ambiguous point of the conventional Gibbs treatment iseliminated. This method is being utilized in the thermodynamic treatment of surface tension ("Molecular theory of surface tension in liquids"
written in collaboration with Prof. S. ONO, Tokyo University, for the
Handbuch der Physik Vol. 10).

* (ct. J. Chern. Phys. 25, 662-669, 1956).

BOOKS AND PAPERS WRITTEN BY STAFF MEMBERS

101

BOOKS AND PAPERS PUBLISHED IN 1956
BY STAFF MEMBERS
ABE, Y. and K. HAYASHI. 1956. Studies on anthocyanins, XXIX. Further studies on
paper chromatography of anthocyanins, involving an examination of glycosidetypes by partial hydrolysis. Bot. Mag. Tokyo. 69 (822): 577-585.
ENDO, T. 1956. Analysis of flavone pigment in Triticum and its related generawith reference to genome constitution. Jap. Jour. Genetics 31: 109-114.
FUJII, T. 1956. Mutations in Einkorn wheat induced by X-rays. II. Virido-albina
mutants. Proc. Japan Acad. 32 (7): 494--499.
1956. Virido-albina mutant in diploid wheat induced by X-rays. WIS
3: 11-12.
GOTOH, K. 1956. Variance and covariance analysis of quantitative inheritance in
eggplant. (in Jap. with Eng. resume) Jap. Jour. Breed. 6 (3): 180-184.
- - 1956. Genetic analysis of varietal differentiation in cereals. III. Competitive ability of local strains of the barley variety" Hosogara No.2". Jap. Jour.
Genetics 31 (1): 1-8.
- 1956. Genetic analysis of varietal differentiation in cereals. IV. Polygenic differences in agronomic characters between local strains of a barleyvariety" Hakata No.2". Jap. Jour. Genet. 31 (6): 172-175.
HAYASHI, K. and Y. ABE. 1956. Studien tiber Antnocyane, XXVIII. Papierchromatographische Dbersicht der Anthocyane im Pflanzenreich, (III). Dber Anthocyane
der Gebirgspflanzen. Bot. Mag. Tokyo. 69 (815): 227-235.
Hu, C. 1956. Cytogenetic studies in Nicotiana XII. Reduction divisions in hybrids
between N. hngsdorffii and three other species. Jap. Jour. Breed. 6 (2) 117-121.
ISHIHARA, T. 1956. Cytological studies on tortoiseshel1 male cats. Cytologia 21(4): 391-398
KIHARA. H. 1956. Search for origin of cultivated plants. Kagaku, 26: 81-87 &135-140.
-, K. YAMASHITA and M. TANAKA. 1956. A new strain of Triticum polonicum. Wheat Inform. Servo 4: 3.
_. (editor) 1956. Land and Crops of Nepal Himalaya. 562 p. Japan Society
for the Promotion of Science, Tokyo.
- - (editor) 1956. Expedition of Deserts and Glaciers. 298 p. (in Jap.) Asahi
Press, Tokyo.
KIMURA, M. 1956. Random genetic drift in natural populations. (in Jap. with Eng.
resume) Population Genetics: 168-183.
1956. Random genetic drift in a tri-al1elic locus; exact solution with acontinuous model. Biometrics 12: 57-66.
1956. Rules for testing stability of a selective polymorphism. Proc. Nat.
Acad. Sci. 42: 336-340.
- - - - 1956. A model of a genetic system which leads to closer linkage by
natural selection. Evolution 10: 278-287.
1956. Stochastic processes and distribution of gene frequencies under

102

BOOKS AND PAPERS WRITTEN BY STAFF MEMBERS

natural selection. Cold Spring Harbor Symposia on Quantitative Biology 20:
33-53.
----- and J. F. Crow. 1956. Some genetic problems in natural populations.
Proc. 3rd Berkely Symposium on Math. Sta. and Probability. IV: 1-22. (Univ.
of Clif. Press).
KIMURA, M. and J. Lederberg. 1956. Transduction mapping. Microbial Genetics
Bulletin 13: 38-40.
KOMAI, T. 1956. Population genetics and its application. (in Jap. Population Genetics(Baifukan, Tokyo): 3-12. with Eng. resume).
1956. Genetics of lady· beetles. Advances in Genetics, VIII: 155-188.
1956. Genetics of Japan, past and present. Science 123: 823-826.
1956. The origin of tortoiseshell male cat and its sterility. Proc. XIV
Int. Congr. Zool.: 144.
1956. Inheritance of coat colors in cats, and the origin of tortoiseshellmales. (in Jap. with Eng. resume) Population Genetics: 39-44.
-- - and S. AB. 1956. Population genetics of butterflies. (in Jap. with Eng.
resume) Population Genetics: 77-83.
----, M. CHINO and Y. HOSHINO 1956. Population genetics on the lady-beetle,
Harmonia axyridis. (in Jap. with Eng. resume) Population Genetics: 45-60.
- - - and S. EMURA. 1956. Population genetics of the land snail, Bradybaena
miliaris. (in Jap. with Eng. resume) Population Genetics: 61-76.
------ and T. ISHIHARA. 1956. On the origin of the male tortoiseshell cat. Jour.
Hered. 47 (6): 287-29!.
, K. KISHIMOTO and Y. OZAKI 1956. Genetics of microcephaly in man. (inJap. with Eng. resume) Population Genetics: 31-38.
, H. KUNII and Y. OZAKI. 1956. A note on the genetics of vand der Hoeve's
syndrome, with special reference to a large Japanese kindred. Amer. Jour.
Human Genetics 8: 110-119.
, Y. YAMADA, Y. HIRAIZUMI and O. KITAGAWA. 1956. Effect of selection
after X-ray irradiation. D.I.S. 30: 125.
KONDO, S. 1956. Thermodynamical fundamental equation for spherical interface.
Jour. Chern. Phys. 25: 662-669.
LILIENFELD, F. A. and H. KIHARA. 1956. Dextrality and Sinistrality in plants I.
Medicago tuberculata WILLD. Proc. Jap. Acad. 32: 620-625.
---- and
1956. Idem. II. Medicago litoralis ROHDE. Ibd. 32:
626-632.
MATSUMURA, S. 1956. Radiation genetics in wheat III. Relation between chromosome aberrations and X-ray dose or wave length in diploid wheat. Cytologia
21 (2): 107-113.
1956. Chromosome aberration in Einkorn wheat induced by radiations.
WIS 3: 10-1!.
1956. Radiation and heredity. (In Jap.) Kagaku 26 (10): 528-532.
1956. The Radioisotope Research Laboratory recently established in the
National Institute of Genetics. Radioisotopes 5 (1): 60-64.

BOOKS AND PAPERS WRITTEN BY STAFF MEMBERSt

103

MATSUMURA, S. and T. FUJII. 1956. Effect of X-rays on fertility and mutation rate
in Einkorn wheat. WIS 4: 4.
- - - - - and1956. Radiation genetics in wheat II. Relation between themutation effect and the dose or wave length of X-rays in a diploid wheat.
Seiken Zih6 7: 45-51.
, S. SAKAMOTO and T. TATEOKA. 1956. Agropyron and its related genera.
Land and Crops of Nepal Himalaya 2: 249-253.
MURAMATSU, M. and S. SAKAMOTO. 1956. Morning-glories. Land and Crops of
Nepal Himalaya, 2: 193-212.
-- and - - - - 1956. F 1 hybrids between three species of Aegilops andAgropyron intermedium. Wheat Inform. Serv., 4: 14-15.
NAWA, S. and T. TAIRA. 1956. Simple microdetermination of uric acid by usinguricase fermentation. D.I.S., 30: 162.
OKA, H. I. 1956. Polygenic nature of "Gametic-Development genes" controllingintervarietal hybrid sterility in rice. (Phylogenetic differentiation of the cultivated rice XII). (in Jap. with Eng. resume) Jap. Jour. Breed. 6: 51-55.
- - - 1956. Restriction on gene recombination in hybrid populations of rice.
(Phylogenetic differentiation of the cultivated rice XIII). (in Jap. with Eng.
resume) Jap. Jour. Breed. 6: 185-191.
- - - - 1956. Genic analysis of resistance to blast disease in rice, by biometricalgenetic method. Jap. Jour. Genetics 32: 20-27.
---- - 1956. Variation in nucleolar number among varieties of cultivated rice.
Cytologia 21: 44-49.
- - - - 1956. Variation in fertilizer response among rice varieties. Jour. Agr.
Assoc. China, New Series 13:35-41.
OSHIMA, C. and T. TAIRA. 1956. Genetic studies on the balanced polymorphism ofDrosophila rufa. (in Jap. with Eng. resume) Population Genetics: 104-120.
SAKAI, K. I. 1956. Population genetics in relation to plant and animal breeding.
(in Jap. with Eng. resume) Population Genetics (Baifukan, Tokyo): 13-28.
- - - 1956. Studies on competition in plant populations. (in Jap. with Eng.
resume) Population Genetics: 184-211.
- - - - 1956. Studies on competition in plants. VI. Competition between autotetraploids and their diploid prototypes in Nicotiana tabacum, L. Cytologia
21 (2): 153-156.
- - - - 1956. Competition in plants and its relation to selection. Cold Spring
Harbor Symposia on Quantitative Biology, 20: 137-157.
1956. Theoretical studies in plant breeding technique. III. Selection index
for individual plants on the basis of individual measurements, line means andline-group means in autogamous plants. (in Jap. with Eng. resume) Jap.
Jour. Breed. 6 (3): 175-179.
- - - , Y. HIRAIZUMI, T. NARISE and S. IYAMA. 1956. Experimental studies on
migration in Drosophila melanogaster. D.I.S. 30: 149-150.
TAIRA, T. and S. NAWA. 1956. Quantitative measurement of riboflavin, folic acid,and uric acid during metamorphosis of some mutants in Drosophila melanogaster. DJ.S., 30: 153-154.

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BOOKS AND PAPERS WRITTEN BY STAFF MEMBERS

TAKENAKI\, Y. 1956. Japanese morning glory. Exhibits, International Genetics
Symposia, 1956. 1-14. with 3 plates.
-- 1956. Cytogenetic studies in Nicotiana IX. Reduction divisions in hybrids
between N. tabacum and two other species. lap. lour. Genet. 31 (4): 104-108.
- - - - 1956. Ditto X. Reduction divisions in N. langsdprffii. Bot. Mag. Tokyo
69, 813: 162-165.
- - - 1956. Ditto XIV. Reduction divisions in five interspecific hybrids. lap.
lour. Genet. 31 (5): 155-16l.
- - - and M. TANAKA. 1956. Ditto XIII. Haploid plant of Nicotiana tabacum.
Bot. Mag. Tokyo 69, 814: 193-198.
TANAKA, Y. 1956. Genic analysis of lapanese long-tailed fowl. (Pub. by the Committee for Genetic Studies on the lapanese long-tailed fowl; in lap.).
T ATEOKI\, T. 1956. Miscellaneous papers on grass phylogeny (1). On the tribe
Phalarideae. (In lap.) lour. lap. Bot. 31: 1-5.
------ 1956. Ditto (2). On the tribe Aveneae. (In lap.) Ibid. 31: 84-90.
------ 1956. Ditto (3). On Festuceae (Part 1), Triticeae and Monermeae. (In lap.)
Ibid. 31: 179-186.
- - - - 1956. Ditto (4). On the tribe Festuceae (Part 2). (In lap.) Ibid. 31:
241-248.
- - - - 1956. Ditto (5). Phylogenetic considerations on the subfamily Festucoideae.
(In lap.) Ibid. 31: 267-272.
- - - 1956. Ditto (6). A review of the subfamily Eragrostoideae. (In lap.) Ibid.
31: 307-315.
-- - - - 1956. Ditto (7). A review of Panicoideae. (In lap.) Ibid. 31: 353-358.
- - - - - 1956. Reexamination of anatomical characteristics of the leaves in
Eragrostoideae and Panicoideae (Poaceae). (In Jap.) Ibid. 31: 210-218.
1956. On the systematic position of the Cleistagenes with special reference
to the characteristics of epidermis and the structure of leaf. (In lap.) Ibid.
31: 326-332.
- - - 1956. Karyotaxonomy in Poaceae IV. Chromosomes and systematic relationships of several species. Bot. Mag. Tokyo 69: 112-117.
- - - 1965. On morphological convergence between Brachypodium sylvaticum
and Agropyron yezoense. Cytologia 21: 146-152.
- - - 1956. The place of the genus Phyllorachis in the system of Gramineae.
Bot. Mag. Tokyo 69: 83-86.
- - - 1956. Notes on some grasses, I. Ibid. 69: 311-315.
- - - 1956. Ditto, II. Ibid. 69: 336-339.
TSUDA, S. 1956. Electron microscopical studies of ultra-thin sections in Penicllium
chrysogenum. lour. Bact., 71 (4): 450-453.
TSUJITA, M. 1956. The genetic relation between the" lem l " gene and the "al"gene. lap. lour. Genet. 31 (12): 327-330.
____ 1956. Theories on the structures of genetic units in microorganisms.
Kagaku 26 (10): 515-52l.
_ _ _ and C. MATSUI. 1956. On a new type phage produced from a double lysogenic strain of Pseudomonas solanacearum. Jap. Jour. Genet. (in the press ?).

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105

TSUJITA, M. and C. MATSUI. 1956. Lysogenic conversion of some genetic characters
including sugar fermentation in Pseudomonas solanacearum. Proc. Intern.
Genet. Symp.
------ and B. SAKAGUCHI. 1956. Genetical embryological studies of the E-allelicseries in the silkworm: The action of the two new genes, EMs and EMc. lap.
Jour. Genetics 31 (7): 207-216.
M., S. TSUDA and K. WATANABE. 1956. Fine structure of mitochondria in
Paramecium. (in Jap.) Denshikenbikyo, Electron microscope 4 (3): 13-17.
YOSIDA, T. H. 1956. Variation in elytral pattern of the convergent lady bird
(Hippodamia convergens) collected in Colorado. Ann. Zool. Japon. 29: 101-103.
- - - and T. ISHIHARA 1956. A simple squash technique for observations ofchromosomes in animals. La Kromosomo 29: 1005-1009.

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