NATIONAL INSTITUTE OF GENETICS(JAPAN)ANNUAL REPORT
No.6(1955)•f~

Published by

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

1956

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Annual Report~f'of theNational Institute of Genetics
No.6,

1955

Published by

The National Institute of Genetics (Japan)
1956

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CONTENTS
General statement .. . . . . . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . . . .
Abstracts of diary for 1955
Staff
Research program for 1955 . . .. .. . . .. .. . . . . .. .. .. .. .. .. .. .. .. . . .. ..
Researches carried out in 1955.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . .

1
3
4
5
9

A. Human genetics, .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
9
1. Genetics of van der Hoeve's syndrome.. .. .. .. .. .. .. .. .. .. ..
9
2. Tests for partial sex-linkage of the gene for achromatopsia..
9
3. Sex ratios among sibships showing xeroderma pigmentosum
and achromatopsia.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
B.

Genetics and cytology of mammals and some other animals ..
4. Studies on a new mutant "Tremor" in the house mouse.. . .
5. Studies on the t-alleles in populations of a Japanese wild mouse
6. Cytological and genetical studies on sterility in mammals, 1.
Spermatogenesis of male tortoiseshell cats
7. CytologIcal and genetical studies on sterility in mammals, II.
Note on a hydrotestis found in the Wistar-King-A rat strain
8. A new micromelic mutant in domestic fowl . . . . . . . . . . . . . . . .
9. The sex chromosomes in Hyla arborea japonica GUENTHER.. ..
10. Karyotype of Apus aecqualis PACKARD (Phyllopoda, Crustacea)(

J

C. Cytology of tumors
11. Utility of a pretreatment technique using hypotonic RINGER'S
solution for observation of chromosomes of various animals
12. Utility of various concentrations of chloride solutions forchromosome study . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . .. . . . .
13. Comparative study of chromosomes in normal hepatic andascites hepatoma cells of the rat..........................
14. Karyological observation on a hepatoma developed in thewhite rat
15. Observations on hyperploid cells in regenerating liver afterpartial hepatectomy of the rat

11
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12
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18
20
21
22
23

D. Genetics and biochemistry of the silkworm and other insects
16. Bi- and uni-lateral variations in certain characters of the silkworm due to unstable genes
24

CONTENTS

ii

17.
18.

A new Eca strain of the silkworm .. . . . . . . . . . . . . .. . . . . . . . . . .
A No-lunule mutant in the silkworm induced by X-ray treatment
Induction of the mutants Eca and NI by X-ray treatment.. ..
Studies on maternal inheritance of the lethal yellow in thesilkworm. Exchange of ovaries between +/lem l and lem/
lem l larvae
Genetical and biochemical studies on the yellow lethal silkworm.
IV. Changes in quantity of pterin compounds in Explanted
ovaries
Genetical and biochemical studies on the yellow lethal silkworm.
V. On the metal metabolism of this mutant..............
Photoperiodic effects of alternated dark and light phases on
diapause of Antheraea pernyi.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Genetical and biochemical studies on pteridine metabolism ..
Biochemical studies on the hibernating character in the Chinese
tussah silkworm, Antheraea pernyi II. The role of sugar
metabolism in hibernation

28

E. Population genetics of some insects and a land snail .. . . . . . . . .
26. Population genetics of a ladybeetle and a land snail
27. Population genetics of balanced polymorphism in Drosophila
..
..
rufa
" .. ..
28. Variation in the elytral pattern of convergent lady-birds(Hippodamia convergens) collected in Colorado

38
38

19.
20.

21.

22.
23.
24.
25.

F. Genetics and cytology of rice
29. Polygenic nature of "gametic-development genes" in rice ..
30. Restriction of gene recombination in hybrid populations of rice
31. Inheritance of several agronomic characters in a varietal hybridof rice," .. .. ..
32. Observations on natural populations of Formosan wild rice.. ..
33. Karyology of Oryza sativa L. I, Karyological studies on haploid
rice
,"
"
,
G. Genetics and cytology of barley, wheat and Agropyron.. . . . . . .
34. Nullisomic dwarfs and tetrasomic giants in hexaploid wheat..
35. Karyotypes of diploid Agropyron species
36. Agropyron and its related genera collected in Nepal . . . . . . . .
37. Off-type plants observed in a wheat variety, "Saitama No. 27"
38. Polygenic differences in agronomic characters among somelocal strains of a barley variety "Hakata No.2"

30
31

32
33
33
34
34
35
36

37

39
40
41
41
42
44
46
47
48
48
49
50
51
52

CONTENTS

iii

39. Population structure of the barley variety "Iwate Mensury
No.2"
52
H. Radiation genetics of wheat and barley
40. Effect of X-rays on fertility and mutation rate in cereals.. ..
41. Chromosome aberrations in Einkorn wheat induced by irradiation
42. "Virido-albina" mutant in Einkorn wheat induced by X-rays
I. Cytology and genetics of Nicotiana . . . . . . . . . . . . . . . . . . . . . . . . . . . .
43. Cytogenetic studies on the genus Nicotiana, VII
44. Cytogenetic studies on the genus Nicotiana, VIII. A haploid
plant of Nicotiana tabacum.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45. Genetical studies on the cherry-red leaf color in tobacco ....

53
53
55
56
58
58
61
62

J. Genetics and cytology of some flowering plants.. . . . . . . . . . . . . . . 64
46.
47.
48.
49.

•

50.
51.
52.
53.
54.
55.
56.

Further investigations of sex chromosomes in Rumex acetosa L.
Cytogenetics studies on the hybrid between Lilium tif?rinumand L. Maximowiczii.... . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The degree of heritability of five characters in eggplant ....
Genetics of the photoperiodic behavior of Japanese morning
glory, Pharbitis Nil CHOIS., a short-day plant.. .. .. .. .. .. ..
Polyembryony in Citrus
Parthenocarpy in Citrus Natsudaidai
Polyploid grape varieties.. .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F 2 offspring of the hybrid between watermelon and colocynthe
Heading and flowering of sugar cane........................
Production of triploid sugar beet seeds.. . . . . . . . . . . . . . . . . . . . .
Karyotaxonomic studies in Poaceae, III .. . . . . . . . . . . . . . . . . . . . .

K. Genetics and Biochemistry of plant pigments..................
57. Studies on natural anthocyanins
58. Genetic control of acylation of anthocyanin pigment in eggplant
59. Further analytic studies of flower pigments of Japanese morning glory in relation to flower color inheritance . . . . . . . . . .
60. Separation of natural anthocyanins by column chromatography
Studies on competition.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chromosome number, hybridity and competitive ability in rice
Further note on the effect on competition of a varying numberof competing and non-competing individuals
63. Possible establishment of an equilibrial state due to competitionin mixed populations of autogamous plants.. . . . . . . . . . . .. . .

L.

61.
62.

64
66
67
68
69
70
70
71
71
72
73
74
74
75
76
77
78
78
79
80

CONTENTS

iv

64. Competition between autotetraploids and their diploid prototypes
in Nicotiana tabacum L. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
65. Variations in competitive ability among varieties and hybrid
strains of rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
66. Variation in competitive ability of rice varieties appearing in
response to the method of growing.. . . . . .. . . . . . . . . . . . . . . . . 84
M.

Genetics and cytology of microorganisms and viruses

67. Electron-microscopical studies of ultra-thin sections of Penicillium chrysogenum II. The fine structure of mitochondrialike cytoplasmic granules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
68. Studies on a double lysogenic strain of Pseudomonas solanacearum
69. Studies on the lysogenicity of Pseudomonas solanacearum: I.
Removal of lysogenicity of the bacterial strain T -c200 by
ultra-violet irradiation
70. Studies on the multiplication of bacterial virus affecting
Streptomyces f{riseus (II)

85

85
87

87
89

N. Theoretical Genetics.. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
71.

Index for individual selection in autogamous plants on thebasis of individual measurements, line means and line-groupmeans....................................................
72. Formulas for estimating the effect of one chromosome on aquantitative character by the so-called "reciprocal·translocation method"
73. Solution of a process of random genetic drift with a continuous
model.. .. .. ..
74. Stochastic models for senescence in Paramecium based on
random segregation of macronuclear elements
75. Genic selection in a finite population (Interaction between genic
selection and random genetic drift).. . . . . . . . . . . . . . . . . . . . . . .
76. Rules for testing stability of selective polymorphism
Books and papers published in 1955 by staff members

90

92
93
94
96
97
99

Radio Isotope Laboratory

GENERAL STATEMENT
In the current year the Institute has acquired a new department, theDepartment of Mutational Genetics, devoted to the study of mutations,especially those induced by irradiation and chemical agents. S. MATSUMURA
has been appointed to take charge of this department, with two new staff
members, T. SUGAWARA and S. KONDO, to work in cooperation with him.
Thus, our Institute has now six departments with 36 research members
including 9 part-time or associate members.
K. OGUMA retired in Oct. 1955 from his directorship, and was replacedby H. KIHARA, formerly professor of genetics in Kyoto University and also
our part-time staff member. Oguma will continue at the Institute as a
research associate.
T. KOMAI, K. SAKAI, as well as M. KIMURA who is on leave of absenceat the University of Wisconsin, were invited to .take part in the Symposium
on Population Genetics held at Cold Spring Harbor, L.I., N.Y. June 6~13,
under the sponsorship of the Long Island Biological Association, where
they read papers. They also attended, by invitation, the Symposium on
Mutation sponsored by the Biology Department of Brookhaven National
Laboratory held at the Laboratory June 15-17. Before and after these
symposia, both KOMAI and SAKAI travelled rather extensively in the UnitedStates visiting many laboratories and institutes of genetics.
A new concrete building, 65 tubo in floor dimensions, designed for2

GENERAL STATEMENT

genetic studies with isotopes, is being constructed and will be completedby March 1956. Five residential houses for staff members, with land,
were donated by Sizuoka Prefecture. A test barn for poultry breedingwith accessory equipment was given to the Institute by the Whole-Japan
Association of Poultry Genetics for the use of the Department of Applied
Genetics.
The library has steadily expanded by acquisition of new periodicals,
books and reprints, by purchase, donation or exchange. Dr. R. GOLDSCHIMIDT
especially has continued to send many new reprints, books and periodicals
which now total 1,138. These are of immense value and great help
to our research.
The Institute was honored by the visit of H.I.H. the Crown Prince
AKIHITO on April 13, 1955. The Prince, who is the heir of the Emperor
with respect to both the throne and biological studies, spent more thanfour hours in the Institute, showing great interest in reports and demonstrations made by four staff members, and in equipment belonging to theInstitute.
Among the foreign visitors during the current year, were: Dr. K. SUGIURAof the Sloan Kettering Institute for Cancer Research, New York, Drs.
R. BRADFIELD and R. F. CHANDLER of the Rockefeller Foundation, Dr. andMrs. D. C. WARREN of Purdue University, and Dr. and Mrs. F. J. RYAN of
Columbia University and Fulbright Exchange Professor at Tokyo University.
The following grants were given during the current year to aid researchby our staff.
From the Fund for Grants-in-Aid of the Ministry of Education to Researches in Institutions: to the Director, for Radiation genetics and its
application to practical breeding ¥ 5,600,000.
From the Fund for Grants-in-Aid to Cooperative Investigations: to
T. KOMAI and co-workers (including K. SAKAI), for: Studies on heterosis¥850,000; to K. OGUMA and co-workers (including T. KOMAI, S. MAKINO,
T. H. YOSIDA and K. TUTIKAWA), for: Cytological and genetical researches
on tumors ¥ 600,000; to Y. TANAKA and co-workers (including M. TSUJITA),
for: Studies on linkage in the silkworm ¥ 480,000; to K. SAKAI andco-workers (including T. KOMAI and H. OKA), for: Studies on polygenic
inheritance ¥ 550,000; to S. MATSUMURA and co-workers, for: Researchesof physiological genetics of crop plants under standardized temperature,humidity and day-light conditions ¥ 550,000; Y. TAKENAKA and co-workers(including K. HAYASHI), for: Genetics of the morning glory ¥ 400,000.
From the Fund for Grants-in-Aid to Investigations in Applied Sciences:
to Y. TANAKA, for: Research on artificial control of diapause in the wild

ABSTRACTS OF DIARY FOR 1955

3

silkworm, Antheraea pernyi ¥ 200,000.
From the Fund for Grants-in-Aid for Promotion of Improvement ofAgricultural Techniques of the Ministry of Agriculture and Forestry; to
K. SAKAI for: Comparative studies between pedigree method and bulk
method in plant breeding ¥ 85,000; to M. TSUJITA, for: Studies on midgut
polyhedrosis of the silkworm ¥ 90,000.

ABSTRACTS OF DIARY FOR 1955
Jan. 13.
Meeting of Organization Committee of the International Genetics
Symposia.
Jan. 19.
Meeting of the Society of Biometrical Genetics.
Jan. 20.
Meeting of the group of investigators on the wild silkworn
Antheraea pernyi.
Jan. 27.
Twelfth meeting of Board of Councillors.
Jan. 28.
Thirty-third meeting of Misima Geneticists' Club.
Symposium on Genetic Studies on Tobacco Plants.
Feb. 17.
Feb. 21.
Meeting of Biology Group in the Special Committee of theStudy of Effects of Radiation.
Feb. 28.
Thirty-fourth meeting of Misima Geneticists' Club.
Ninth meeting of Biological Symposia.
March 18.
March 21.
Thirth-sixth meeting of Misima Geneticists' Club.
March 25.
Thirth-seventh meeting of Misima Geneticists' Club.
March 25.
Thirty-fifth meeting of Misima Geneticists' Club.
Tenth meeting of Biological Symposia.
March 26.
April 13.
The Crown Prince's visit.
April 20.
Meeting of Organization Committee of the International
Genetics Symposia.
May 10.
Eleventh meeting of Biological Symposia.
July 1.
General meeting of Whole-Japan Association of Poultry Genetics.
July 15.
Thirth-eighth meeting of Misima Geneticists' Club.
July 26.
Thirteenth meeting of Board of Councillors.
August 4. Meeting of Organization Committee of the International
Genetics Symposia.
August 16.
Meeting of poultry breeders to discuss the methods ofimprovement of poultry strains.
September 20.
Thirty-ninth meeting of Misima Geneticists' Club.
October 7.
Fortieth meeting of Misima Geneticists' Club.
Forty-first meeting of Misima Geneticists' Club.
October 29.
Forty-second meeting of Misima Geneticists' Club.
November 7.

STAFF

4

November 9.
Meeting of Committee of Exhibits for the International
Genetics Symposia.
~ovember 27.
Twelfth meeting of Biological Symposia.
November 30.
Forty-third meeting of Misima Geneticists' Club.
Thirteenth meeting of Biological Symposia.
December 3.

STAFF
Director
Hitoshi KIHARA, D.Sc.

Department and Laboratory Heads
Yoshimaro TANAKA, D.Ag., D.Sc., Head of Department of Morphological
Genetics
Taku KOMAI, D.Sc., Head of Department of Physiological Genetics
Ya TAKENAKA, D.Sc., Head of Department of Cytological Genetics
Mitsuo TSUJITA, D.Ag., Head of Department of Biochemical Genetics
Kan-Ichi SAKAI, D.Ag., Head of Department of Applied Genetics
Seiji MATSUMURA, D.Ag., Head of Department of Mutational Genetics
Tosihide H. YOSIDA, D.Sc.
Kaza HAYASHI, D.Sc.
Hiko-Iehi aKA, D.Ag.

Part-time Staff and Research Associates
Kan OGUMA, D.Ag. Emeritus Professor of Hokkaido University
Sajir6 MAKINO, D.Se., Professor of Hokkaido University
Yosito SINoTa, D.Se., Professor of International Christian University
Hideo ETa, D.M., Assistant Professor of Tokyo University
Kazlio FURUSATO
Yoshinari KUWADA, D.Sc., Emeritus Professor of Kyoto University
Flora Aliee LILLIENFELD, Ph.D.
Yasunosuke OZAKI, D.M.
Katumi TANAKA, D.M.

Junior Investigators

Mota KIMURA, on leave of absence
Kanji GOTOH
Akira MIYAZAWA
Bungo SAKAGUCHI
Tetuo hNO, on leave of absence
Toshifumi TAIRA

Taru ENDO
Kiyosi TUTIKAWA

Takatada KAWAHARARESEARCH PROGRAM FOR 1955

Saburo NAwA
Seizo TSUDA
Tsuguo T ATEOKA
Yukio YAMADA
Yukihide ABE

5Takaaki ISHIHARA
Taro FUJII
Sadao SAKAMOTO
Kimiharu ONIMARU
Assistants 15

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

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

Seiji IMAI
Assistants 4Whole-Japan Association of Poultry Genetics
Kan OGUMA, President
Yoshimaro TANAKA, Vice-President and Director of Researches

Association for Propagation of the Knowledge of Genetics
Kan OGUMA, President
YO TAKENAKA, Managing Director
Seiji MATSUMURA, Managing Director

RESEARCH PROGRAM FOR 1955
Department of Morphological Genetics (TANAKA)
First Laboratory (TANAKA)
Studies on unstable genes in silkworm (TANAKA)
Linkage in silkworm (TANAKA)

Second Laboratory (KIHARA)
Studies on the ancestry of wheat (KIHARA)
Studies on substitution of nucleus in wheat (KIHARA)
Studies on Agropyron, a relative of Triticum (MATSUMURA and SAKAMOTO)

6

RESEARCH PROGRAM FOR 1955

Nullisomic dwarfs among the offspring of pentaploid wheat hybrids(MATSUMURA)
Physiological genetics of the reaction of morning glory to day length(SAKAMOTO)

Third Laboratory (KOMAI)
Genetics of van der Hoeve's syndrome (KOMAI et al.)Partial sex-linkage in man (K. TANAKA)

Department of Cytological Genetics (TAKENAKA)
First Laboratory (YOSIDA)
Cytology and genetics of tumors (OGUMA et al.)
Karyological characteristics of tumor cells (OGUMA, MAKINO and YOSIDA)
Genetics of tumor susceptibility (YOSIDA and ISHIHARA)
Histology and cytology of testes of male tortoiseshell cats (ISHIHARA andYOSIDA)
Determination of sex and sex-chromosomes in animals (YosIDA and ISHIHARA)
Cytogenetics with tissue culture method (YOSIDA)

Second Laboratory (TAKENAKA)
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 and LILIENFELD)
Genetics of Pharbitis Nil (TAKENAKA et al.)Classification of Gramineae by karyotypes (TATEOKA)
Karyology of rice plant (TAKENAKA)

Third Laboratory (TSUJITA)
Studies on minute structures of cells with electron-microscope (TSUJITA,TSUDA and WATANABE)
Virus, especially its genetics (TSUJITA, TSUDA and YOSHIZAWA)

Department of Physiological Genetics (KOMAI)First Laboratory (KOMAI)
Studies on heterosis (KOMAI et al.)Problems on mouse genetics (KOMAI and TUTIKAWA)
Population genetics of the lady-beetle, Harmonia axyridis (KOMAI)
Population genetics of the land-snail, Bradybaena similaris (KOMAI)
Population genetics of Drosophila rufa (TAIRA)The T locus in Mus musculus molossinus (TUTIKAWA)RESEARCH PROGRAM FOR 1955

7

Second Laboratory (OKA) and Third Laboratory (SAKAI)
Analysis of genes responsible for hybrid sterility in rice (OKA)
Analysis of genes controlling temperature response in germination of rice
(OKA)
Heritability of various characters and genetic correlations in rice (SAKAI
and OKA)
Population-genetic studies on wild rice plants (OKA)

Department of Biochemical Genetics (TSUJITA)First Laboratory (TSUJITA)
Biochemical genetics of insects and microorganism (TSUJITA, NAWA andSAKAGUCHI)
Embryological and biochemical studies of silkworm (TSUJITA and SAKAGUCHI)
Biochemical studies of some mutants in silkworm and Drosophila (NAWA
and TAIRA)

Second Laboratory (HAYASHI)
Biochemistry of the mechanism underlying variations in flower colors due
to anthocyanins, especially blue colors (HAYASHI and ABE)
Biochemical genetics of flower colors in Viola tricolor (ENDO)
Genetic studies of anthocyanin pigments in the varieties of eggplant (ABEand GOTOH)

Department of APPlied Genetics (SAKAI)First Laboratory (TANAKA)
Breeding for high egg production in poultry (TANAKA and KAWAHARA)
Genetics of some hereditary nervous diseases in poultry (KAWAHARA)
Heritability and genetic correlation of economic characters in poultry(YAMADA)
Genetic study of long-tailed fowl (TANAKA)
Experiments on the control of diapause in Antheraea pernyi (TANAKA)
Studies on variation of quantitative characters in inbred mice and Drosophila and effect selection on them (YAMADA)

Second Laboratory (SAKAI)Studies on polygenic inheritance (SAKAI et al.)Studies on competition between plants of differents genetic constitution(SAKAI et al.)Population-genetic studies of "red rice" growing among land rice (SAKAI
et al.)8

RESEARCH PROGRAM FOR 1955

Comparative studies of pedigree method and bulk method (SAKAI)Studies on the nature of "good" characters in tobacco plants (SAKAI)
Local differentiation of races in barley (GOTOR)
Genetic studies on quantitative characters of eggplant (GOTOR)
Polyploidy and sterility in fruit plants (FURUSATO and MIYAZAWA)

Department of Mutational Genetics (MATSUMURA)First Laboratory (MATSUMURA)
Radiation genetics and its practical application (KIHARA et a1.)
Relation between the quality of radiations and mutations (MATSUMURA, ETO
and FUJII)
Radiation genetics of wheat and barley (MATSUMURA and FUJII)
Mutations induced by irradiation of tobacco plants (KIHARA, MATSUMURA
and FUJII)
Cytogenetic studies of the effect of substances inducing mutations and of
substances inhibiting mitosis (TAKENAKA)
Physiological and genetical studies on cultivated plants under controlledtemperature, humidity and day-light conditions (MATSUMURA et a1.)
Breeding of triploid plants and its practical applications (MATSUMURA et a1.)

RESEARCH STUDENTS AND RESEARCH ITEMS
Kyozo WATANABE: Cytology and genetics of infusorians
Yasuo SUZUKI: Population genetics of crop plants
Setsuji KATAOKA: Cytology of interspecific hybrids of lilies
Shin-ya IYAMA: Population genetics of upland rice
Yasu ONO: Cytogenetics of domesticated animals
Osamu YOSRIZAWA: Genetic studies of bacterial virus
Yoshito OGAWA: Cytogenetics of animals
Keiko SRIRATO: Genetics of Drosophila
Yasuo OTA: Cytogenetic studies of polyembryony in Citrus
Yutaka So: Karyological studies of inhibitory effect of various agents on
tumorous growths
Yuichiro HIRAIZUMI: Polygenic inheritanceRESEARCHES CARRIED OUT IN 1955
A.
1.

HUMAN GENETICS

Genetics of van der Hoeve's Syndrome(By Taku KOMAI)

A large kindred showing van der Hoeve's syndrome was discovered by
Dr. H. KUNII who runs an ophthalmological hospital in Yamagata Prefecture.
The members of this kindred were repeatedly examined by him and also
by Dr. Y. OZAKI, research associate of our institute, and an extensive
pedigree chart was completed. Based on this chart and accompanying
records, KOMAI conducted a genetic study of this kindred. It has beenconcluded that the abnormalities found in many of the members, bluesclera, bone fragility, luxation of joints, deafness, as wel1 as short stature
and a large head, are probably due to pleiotropic manifestations of a single
autosomal dominant gene. The manifestation of this gene, especial1ywith regard to bone fragility, varies widely. It may cause" osteogenesis
imperfecta congenita", which is a rare lethal or sublethal abnormality
causing pre-natal death of the afflicted child, or milder defects whichappear in the post-natal period. Among the latter, there is an almost
complete series ranging from severe crippling appearing in babyhood toapparent normality throughout life. Based on the data of the frequencyof "osteogenesis imperfecta congenita" recorded for Scandinavian people
and defects of the milder type estimated for Japanese, the rate of mutation of the gene for this syndrome was estimated. The value 3.95 X 10- 0
was obtained as a first approximation of the mutation rate of this gene.

2.

Tests for Partial Sex-linkage of the Gene for Achromatopsia(By Katumi TANAKA)

Among the parents of individuals showing total color-blindness in Japanese
literature, the manner of relationship is known in 20 consanguineous matings.
They include 1 half-sib, 17 first-cousin and 2 second-cousin matings. In 12
matings the husband was related to his wife through his father and theirprogeny were composed of (a) 15 normal males, (b) 18 affected males, (c)17 normal females and (d) 12 affected females. The remaining 8 sibships,
in which the husband was related to his wife through his mother, produced

10

RESEARCHES CARRIED OUT IN 1955

as offspring (a) 11 normal females, (b) 11 affected females, (c) 15 normal
males and (d) 6 affected males. The totals are thus: (a) 26, (b) 29, (c)32 and (d) 18. The crossover value is calculated by using Haldane's
formulas: x=d/(b+d)=0.3830 and x=(2a-c)/(a+c) =0.3448, where x is theestimate of crossover value. Combining these values we obtain x=0.3786±0.0667. The deviation is in the right direction for the hypothesis ofpartial sex-linkage, but it is not significant, since the difference between
0.5 and 0.3786 is only 1. 82 times the standard error.
Excluding the above-mentioned cases, 26 complete sibships including individuals showing this defect were analyzed by use of the indirect method(Finney's first method), The total linkage score SeA) is + 15.55554. The
total information S(K) is 56.00002. Therefore the standard error is{S(K)}1/2=7.483, whence t=15.55554/7.483=2.08, which corresponds toa probability lower than 1. 9 %, thus being significant. The estimate of
the crossover value is given byx=
whence we obtain x= 0.2365.
3.

~ {l-(~~~n~}Sex Ratios among Sibships showing Xeroderma
Pigmentosum and Achromatopsia(By Katumi TANAKA)

Macklin (1944, 1952) has found in her analysis of the data on xeroderma
pigmentosum that there are more affected males than females in which
the inheritance is through the paternal line of the husband, and more
affected females than males in sibships in which the hushand is related
to his wife through his mother, in agreement with the expectation on the
hypothesis of partial sex-linkage. However, she has noticed a significant
excess of normal males over normal females in the paternal relationshipand an excess of normal females over normal males in the maternal
relationship, and she expresses scepticism of the interpretation of the databy assuming partial sex-linkage.
In the 20 Japanese sibships showing achromatopsics in which the parental
relationship is fully known, the sex ratio has been found to be nearly 1: 1,
i. e. 33 males to 29 females in the families with a paternal relationshipand 21:22 in the families with a maternal relationship.
The remaining 26 complete sibships in which the parental relationshipis not fully known are divided into 3 groups: (A) those in which only
males are affected, (B) those in which only females are affected and (C)those in which both .sexes are affected. The number of boys expected

RESEARCHES CARRIED OUT IN 195511

per family of a given size in group (A) and the number of girls expected
in group (B) may be given by the formula:_ s{2(4-x)S-1-(1 +x)38-l}r - _. ·-(4··-x) B_----3-S ---(1)if the patients are non-crossovers, and by the formula:,_ s{2(3+x)s-l-(2-x)S-1}
r ---- (3+x)"~--""""""""".. (2)if the patients are crossovers, where s is size of sibship and x the crossover value. The value r is always smaller than r' as long as the crossover value is smaller than 0.5.
Assuming x=0.5, the numbers of children to be expected in Macklin's
xeroderma families and in the present author's achromatopsia families
were calculated, and compared with the observed numbers. As shown in
the table, the expected numbers are in good agreement with the observed.
Number of boys
in group (A)Achromatopsia
Xeroderma pig.

Observed
40
125

Expected
41.650124.061

Number of girls
in group (B)Observed
26
96

Expected
23.70491.145

If it is assumed that x=0.2 or 0.3, and that all patients in groups (A)and (B) are non-crossovers, the numbers of children calculated by using
formula (1) are smaller than the observed numbers listed above, but thedeviation is not significant in either case. The deviation would become
smaller if the expected number were larger as there would be some crossovers, and, in these cases, the numbers of children should be calculated
by formula (2).
Thus there is no evidence of disturbance of the sex ratio among totalsibs which might cause an abnormal sex distribution among affected sibsin the families with these diseases.

B.

GENETICS AND CYTOLOGY OF MAMMALSAND SOME OTHER ANIMALS

4. Studies on a New Mutant " Tremor" in the House Mouse(By Kiyosi TUTIKAWA)

A new anomaly appeared as a spontaneous mutation in 1953, in a
mildly inbred" deformed pinna" strain maintained in our laboratory. Its

12

RESEARCHES CARRIED OUT IN 1955

origin probably had been within the few previous generations. It wasnamed" Tremor" (Mouse News Letter, 12:44).
Tremor (symbol tm) is due to a recessive gene with a regular manifestation. As no tremor males breed, most data are from matings between
two heterozygotes, which produced altogether 88 normals and 27 tremors.
The syndrome is rather complex, and needs minute pathological examination for any detailed description.
The abnormality is hard to recognize with certainty until about 17 daysof age. By careful daily examination of young mice about two weeks
old, however, the abnormality may be detected. At this stage, the affectedanimals show a slight tremor of head and body. At three weeks, they
are apparently more active than their normal sibs, and run about
vigorously. They can climb up the wire gauze wall, and walk across anarrow bridge without any difficulty.
At this stage, however, thesemutants show a pronounced tremor of the hind legs when initiating
purposeful movements or when excited. Later, in the fifth or sixth weekof life, a progressive paralysis of the hind legs appears, with tremor andloss of coordination; the animal can no longer sit up on its haunches, thegait becomes progressively slower, and overbalancing of the hindquarters
begins. The affected males seem to be sterile, probably because of
mechanical difficulties in copulation due to the inability of coordinatedmovements. The females are fertile and nurse their own litters.
This new mutation differs in its manifestation from the well-known
defects deaf, choreic or waltzing. It has some features in common withagitans, ag, ataxia, ax, reeler, rl, vacillans, VC, and wobbly, wh, but it isrelatively closer to quivering, qr. No genetic test has been made bycrossing tm and qr, but tests for the linkage relationships of the genefor tremor are in progress.

5.

Studies on the t-alleles in Populations of a Japanese Wild Mouse(By Kiyosi TUTIKAWA)

Samples of populations of the wild mouse, Mus musculus molossinus,
caught in three different localities, Misima, Niigata and Fukuoka, were
tested for the t gene by mating them to a standard testing stock TI+(Brachy) of M. m. musculus. Some wild mice from these three sources when
so tested produced, in addition to the expected Brachy (TI +) and normal
offspring, tailless offspring which on further testing proved to be Tit"',and gave rise to seven new tailless lines.
The t m alleles obtained from these populations of Mus m. molossinus

RESEARCHES CARRIED OUT IN 1955

13

resemble in their genetic properties the t- or til' "alleles of Mus J11. musculus
reported by Dunn. Wild males, +It III , seem to produce a great excess
of till sperm. The ratio of tIlt to + sperm is approximately the same as
the ratio of taiIIess Tlt lll to Brachy TI+ offspring, when a +Itm male ismated to a TI + female. For all the 6 +Itm wild males tested, this proportion was 77: 7 (table 1), a ratio of 11 t m to 1 +. A similar apparent
excess of t sperm in males heterozygous for t-alleles has been found in
M. m. musculus (to, t l , t 2 , t 9 , t l2 -Dunn and Gluecksohn-Schoenheimer,
1950; twI, t W \ twa, t w " two-Dunn and Morgan, 1953).
The lethality of the tIlt alleles from the wild molossinus was alsostudied. Each F 1 taiIIess male which had been proved to be Tit'" wascrossed with an F 1 tailless female, similarly tested, and derived from thesame wild male. The F 2 offspring should reveal whether the t'" allele ineach case is lethal or viable. If lethal, the cross Tit'" x Tit'" should produce
only tailless young, since TT and t"'t'" would die before birth. If viable,
till homozygotes would survive, and give young with normal tails. When
this cross was made, the F 2 progeny of one male (k-l, Fukuoka) consistedof 28 tailless and 18 normal animals. This result indicates that the t'"allele is viable and gives a normal tail when homozygous. On the other
hand, the F 2 progeny of a female (m-4411) and three males (m-306, m-802,
m-9515) derived from the same locality (Misima) consisted of 56 taiIIessand 13 normal animals, beside 8 animals with very short tails. No
individual of this last type was found in the previous tests, F 1 taiIIesscrossed with a known Tit" stock. The tentative interpretation is thatthe homozygote for this t m allele is also viable, but that it is occasionally
manifested as a very short tail. Similar breeding results were obtained
for the viable allele derived from two males (n-63, n-65) from Niigata;namely 21 tailless, 9 normals, and one with a very short tail.
Table 1
Wild
parentFemalem-4411
Male
m-306
m-802
m-9515
n-63
n-65
k-l
Totals of
6 males

SourceNormalF j progeny
Brachy+/+; +/tm

T/+

+/t'"

Misima (1)

7

+/tm
+/tm
+/t lll
+/t'"
+/t'"
+/t'"

Misima (I;Misima (1)Misima (2)Niigata
Niigata
Fukuoka

4
10
16
14
7
13

1
2

64

7

TaillessTit'".. _ - - " - - - - - "

+/t'"

4

6
14
23
8
1G
16
77

----

---~--~

14

RESEARCHES CARRIED OUT IN 1955

It is not known wl1('ll1('r the till alle'ks fOllnd in the' wild mire' fromdifferent localities are identical or not. Other questions to be answered
concern: 1) the relative viability and fertility of various t"'/t lll individuals
and 2) the relationship between the t"'-allele found in molossinus and the
tor t"'-alleles known in musculus.

6.

Cytological and Genetical Studies on Sterility in Mammals!.

Spermatogenesis of Male Tortoiseshell Cats
(By Takaaki ISHIHARA)

It is well known that the male tortoiseshell cat is sterile. This sterility
is due to the entire absence of spermatogenesis in the seminal tubules.
According to cytological observations on the testes of six male tortoiseshell cats, there is a great deal of individual variation in the rate ofdegeneration of the male cells. One of these cats entirely lacked spermatogenesis, two contained a few spermatogonial cells in the seminal
tubules, one had its male germ cells developed to the secondary spermatocyte
stage, while two tortoiseshell cats showed apparently normal spermatogensis.
Thus, among the six male tortoiseshells examined, four showed distinct
histological signs of sterility (Fig. 1), while two had apparently normal
testes (Fig. 2) .

•.,. ..

.

,'

2,

Fig. 1. A seminal tubule in the testis of an apparently sterile
male tortoiseshell cat. Fig. 2. Seminal tubules in the testis ofan apparently fertile male tortoiseshell cat.

It is not quite certain whether or not these two male tortoiseshell catscoul:1 have been fertile, but as far as can be judged from the morphologyof their testes, they appear to be perfectly normal. In the testes of thesetwo cats, spermatogonial cells have been found to contain 38 chromosomes
including an X-Y set. In the primary spermatocyte, there are 18 pairsof autosomes and a pair of sex-chromosomes. The X-Y complex consists

..

15

RESEARCHES CARRIED OUT IN 19S5

of il long X and :1 small Y which (Ire associated at their enos. Thus,
these tortoiseshell males have exactly the same chromosome constitution
as the normal male cat.

..
7.

Cytological and Genetical Studies on Sterility in Mammals
II.

Note on a Hydrotestis found in the
Wistar-King-A rat Strain(Ry Takaaki ISHIHARA)

Some rats of the Wistar-King-A strain kept in the Institute havedeveloped hydrotestis (Table 1). This abnormality is found mostly inrats of ten months or older, and seldom in rats younger than six monthsof age. In order to examine whether hydrotestis is a heritable characterhybrids between Wistar-King-A and Wyne-pink-eyed yellow strains were
examined. As shown in the table, some of these F] rats developed thedefect. This observation suggests that the hydrotestis occurring in the
Wistar-King-A strain is a heritable character.
Table l.

Incidence of hydrotestis in rats
I
Total numHydro- ,Doubt- I Normal ber of inFrequency
testis I cas~~l ! testis dividuals
observed

StrainAge
I (in months)'

WKA
WKA
Wyne
W
Mixed strain

10-20
4-6
10-20
10-20
10-20

36
0
0
0
0

3
2
0
0
0

5

44

9

11

25
5
10

25
5
10

81.81
18.18
0.0
0.0
0.0

Fl(WKA~x
Wayne~)

10

2

0

2

4

50.0

The obnormal testis is five or six times as large as normal. The
seminal lobes appear to be suspended in liquid accumulated in the organ.
Histological examination of affected testes reveals remarkable degenerationof the germ cells, so that all rats which develop hydrotestis seem tobe completely sterile.

8.

A New Micromelic Mutant Domestic Fowl.
(By Takatada KAWAHARA)

In the hatching season 1955, seven abnormal embryos called micromelia,
were found among the offspring of full brother-sister matings of White

16

RESEARCHES CARRIED OUT IN 1955

Leghorn. The great majority of theseembryos survived to the end of the incubation period, but none hatched. Some
individuals died after 15 to 18 days of
incubation. The characteristics of theseabnormal embryos are as follows: 1) The
long bones of both extremities are very
short; 2) the beaks, especially the upper
beak, are shortened; 3) the body is soft
Fig. 1. A normal (left) and mi- owing to imperfect calcification of thecromelic (right) embryos, 21days of incubation.
bones; and 4) the amniotic and allantoic
fluids are retained as highly viscous fluids until the end of the incubation
period. The measurements of the long bones in normal and micromelicembryos are shown in Table 1.
Table 1.

Average length of long bones in normal and micromelicembryos, 21 days of incubation.

Description ofembryos

Femur

Tibia

Tarso-metatarsus

Humerus

Ulna

Normal embryos

19.00
±0.54

24.14
±0.30

17.00
±0.28

11.50
±0.21

10.07
±0.21

Micromelicembryos

7.07
±0.39

9.50
±0.33

7.43
±0.27

4.76
±0.33

4.16
±0.19

Difference

11. 93
±0.52

14.64
±0.33

9.57
±0.69

6.74
±0.33

5.91
±0.23

Among the offspring of several matings of parents presumably heterozygous for the gene for micromelia, 339 normal and 99 micromelicembryos were obtained, a ratio approximating 3: 1 (expectation 328.5: 109.5).
Among the normal progeny, about two-thirds were heterozygous, andthere was no indication of any lethality of the mutant gene. The sex
ratio of the micromelic embryos was normal. These results indicatethat this defect is due to a simple autosomal recessive gene. Somebiochemical studies of this mutant were carried out by means of paperchromatography. The most interesting results thus obtained is the findingof an exceedingly large quantity of magnesium and very little calcium inthe micromelic bones. a relation which is just the opposite in the bonesof normal chickens.

9.

The Sex Chromosomes in Hyla arborea japonica GUENTHER(By Tosihide H. YOSIDA)

Since the early works by von RATH (1895) and Carnoy and LEBRUN (1900)

RESEARCHES CARRIED OUT IN 1955

17

several papers have been published dealing with the cytology of amphibians,
yet the problem of sex chromosomes in this group remains unsolved tothis day. The chromosome complex of the frog Hyla arborea japonica
was observed by IRIKI (1939), who reported that the 2n chromosomes ofthis frog are 24 in number, and include a pair of large V-shaped elements
which are apparently X and X; he believed the male to be homogametic.
My observation of the chromosomes of male germ-cells of this frogwith the squash technique has revealed the following facts.
Most
spermatogonial cells contain 24 chromosomes (12-pair), of which 3 pairs
are large and V-shaped, 3 pairs large and J-shaped, and the remaining
6 pairs small and J-or V-shaped (Figs. 2-4). The No.9 pair (shown by" i" in Fig. 4) are unequal one member being somewhat smaller thanthe other, and the two arms of the larger member being of different
length.
This observation suggests that the unlike pair is the sex
chromosomes, the larger chromosome isX and the smaller one, Y.
In the prophase of the spermatogonial cells there is a chromosome

..

3

1
Xy

a
Fig. 1.

b

c

d

e

f

g

h

Chromosomes in prophase in a spermatogonial cell of Hyla arbOre(ljaponicn.
Fig.- 2.
Fig. 3.
Fig. 4.

k

Chromosomes in metaphase in a spermatogonial cell.
Drawing to clarify Fig. 2.
Serial alignment of chromosomes in the cell drawn in Fig. 3.
X=X-chromosome, Y = Y-chromosome.

18

RESEARCHES CARRIED OUT IN 1935

which is remarkable for its behavior, different from that of otherchromosomes. When other chromosomes become indistinct by uncoilingand swelling, this particular one remains quite distinct (Fig. 1). This
chromosome is probably X, as it is similar in shape and appearance to
the X chromosome observed in metaphase cells. Thus, it seems justifiable
to conclude that the male of this frog is of the X-Y type, and that the
male is the heterogametic sex.

10.

KaryotyPe oj Apus aecqualis PACKARD (Phyllopoda, Crustacea)(By Tosihide H. YOSIDA and Hiroyuki HIRUMI)

Among Species belong to the Apodidae, one (Apus sp.) has been cytologically investigated by MOORE (1894). This author reports the striking
fact that the ovarian cells in this species probably contain only one
chromosome.
Material was gathered from a paddy field in the region of Numazu.
Of 43 individuals, collected, 34 were males, and 9 females. According to
VENO (1925) all of the 45 individuals he gathered in the suburbs of Wakayama were females. It is well known that males are rare in animals
belonging to this family, so it is rather noteworthy that in the present
lot, there were more males than females.
The chromosomes revealed by the squash technique were all very small.
The spermatogonial cell contained 12 chromosomes cQnsisting of a large
V-shaped pair and 5 small rod or V-shaped pairs.

C.
11.

CYTOLOGY OF TUMORS

Utility of a Pretreatment Technique Using Hypotonic
RINGFlR'S Solution for Observation of
Chromosomes of Various Animals(By Tosihide H. YOSIDA and Takaaki ISHIHARA)YOSIDA (1955) has found that the metaphase chromosomes in ascites tumor
cells and in male germ cells of the rat may be spread apart from one
another by pretreatment with hypotonic RINGER'S solution: the chromatidsof each chromosome also become distinguishable by this treatment. We
have utilized this technique for the observation of chromosomes in various
animals. It consists of three successive procedures: (1) pretreatment withhypotonic RINGER'S solution (10 min.), (2) staining with acetic orcein, and (3)squashing. Our experiments have shown that the concentration of RINGER'SRESEARCHES CARRIED OUT IN 1955

19

solution should be adjusted according to the type of tissue and the speciesof animal. The proper concentration for each of the species tested isshown in Table 1.
Pretreatment with a hypotonic solution has been utilized for the examination of animal chromosomes by several previous workers (MAKINO
and NISHIMURA 1951, with water: HUGHES 1952, with hypotonic TYRODE'S
solution for tissue culture material: Hsu and POMERAT 1953, with hypotonic
GEY'S solution for tissue culture material: W AHMAN and ZAHAVI 1955, withhypotonic TYRODE'S solution: SCHMIDTKE 1955, with hypotonic NaCl solution:
Table 1. Appropriate concentrations of RINGER's solution forobservations of chromosomes in various materials
Material used
Type of tissue
Speciesor tumor
Male germ cells
Hepatic cells
YOSHIDA sarcoma
Rattus norvegicus
MTK-sarcoma I
MTK-sarcoma II
Hirosaki sarcoma

Appropriate concentrationof RINGER'S solution(Ringer: Water, v/v)
11
110-100100
10-100""1 : 10-20--_.~~~-

Male germ cells
Hepatic cells
Ascites tumor (MORI)
Ehrlich ascites
carcinoma

1
1
1

10-20
100
100

1

10-20

1

Male germ cells

1 : 5

I

Male germ cells

1

20-30

1

50

Mus m1lsculus-- - Lupus cun{culus
domesticus
Felis domestica!

1an;;;s~~1f!yrhyncha

1- Kidney cells~~~~~~~borea!Male germ cells

100

Male germ cells

100

Various-species ofgrasshopper

and YOSIDA 1955, with hypotonic RINGER'S solution). Our studies haverevealed the necessity of selecting a suitable concentration of RINGER'S
solution for each material.
Reference: YOSIDA, T. H. and T. ISHIHARA 1955. A simple squash techniquefor observations of chromosomes. in animals. La Kromosomo 27-28: 1005-1009.

20

RESEARCHES CARRIED OUT IN 1955

12.

Utility of Various Concentrations of Chloride Solutions
for Chromosome Study(By Tosihide H. YOSIDA and Yoshito OGAWA)

To attempt to find the mechanism inducing spreading and splitting ofchromosomes by hypotonic RINGER'S solution, the effects of various concentrations of chloride solutions, such as KCI, NaCl, CaClz, MgCI 2 , FeCI 2 ,FeCh and AICl 3 were examined. The materials used were YOSHIDA
sarcoma, ascites hepatoma No. 7974 and grasshopper gonads. The results
are summarized in Table I.
Table 1.

Spreading and separating effects of various chlorides on chromosomes(treatment with each solution for ten minutes)

Materials

Concentration

YOSHIDAsarcoma

N/10
N/lOO
N/l.OOO
N/lO.OOO

*+

N/l0
N/lOO
N/l.OOO
N/lO.OOO*+ *+Ascites
hepatoma

Grasshopper
gonads

FeCh AICh

+

+

+

N/10
N/lOO
N/l.OOO
N/lO.OOO+-+*
It is clear that KCI, which is the main constituent of

I

-

+

*+

RINGER'S solution,
is not an important agent for spreading and splitting chromosomes. Good
results were obtained using N/1.000 NaCI and N/100 CaCl 2 solutions for
YOSHIDA sarcoma cells, N/100 CaClz and N/100 MgCl 2 solutions for ascites
hepatoma cells, and N/10.000 FeCl 2 and N/1.000 AICl 3 for grasshopper
germ cells.
Based on these results we have made new mixtures of salt solutions
which seem to be suited for the purpose. They are:-

YO I solution (for YOSHIDA sarcoma cells)
fN/l.OOO
NaCl\ N/lOOCaCh
YO II solution (for ascites hepatoma cells)(N/lOO
CaCh(: N/100
MgCb

21

RESEARCHES CARRIED OUT IN 1955
YO III solution (for germ cells of grasshopper)! N/lO.OOO
FeCb\ NIl. 000
A1Ch

13.

•

Comparative Study of Chromosomes in Normal Hepaticand Ascites Hepatoma Cells of the Rat(By Tosihide H. YOSIDA and Takaaki ISHIHARA)YOSIDA (1955) has found that the characteristic V-shaped chromosomes
occurring in the tumor cells of the YOSHIDA sarcoma, the MTK-sarcoma
II and III, and the Hirosaki sarcoma originate by fusion of two different
chromosomes. To know whether such V-shaped chromosomes may befound in the course of development of the tumor, we have studied
chromosomes of hepatic cell in various stages of developing rat hepatoma.
First, the chromosomes of normal hepatic cells and of the transplantable ascites hepatoma of the rat were observed utilizing our squash
technique. Hepatic cells of new-born rats and in the regenerating liver~ ~~~~ ~~&~

~.

X

-~~V

u

~)(
~

+~
~
\\~

.,.

~rl.,
1\ """ "'"~ct ~ ~ ~ U0UVD0IJ U~ 0 0

D,)« UUI'"A

U VU(J 0 ,,\IV II V v u u. Jr II\I 'J II , U U"u "'J u () v, 1/ II , "Vq

II'X)~ X l< K X\t

Xl( l<\ x l:k It MV

R" l( C ~ l()( g It It \'It

Ill' II ) II,I

1 23 4 5 6 1 89 10 1 2 3 4 56 789201 2345 6789 30 1 2 3 4 5 6789401 234 5618

Figs. A and B. Chromosomes of two cells in ascites hepatoma N9. 7974.
Figs. C and D. Serial alignments of these chromosomes. Fig. C corresponds with
Fig. A. Fig. D corresponds with Fig. B. Out of 48,29 are rod-shaped, and 19
V- or J·shaped. Chromosome No. 30 is of a large V-shaped and No. 29 is
dot-shaped.

22

RESEARCHES CARRIED OUT IN 1955of adult rats were used as the normal somatic cells, while, the transplantable ascites hepatoma No. 7974, which originated in the SASAKI Instituteof Tokyo, was used for the tumor material.
In the hepatic cells of new-born rats the chromosome number is highlyvariable (36-84). The majority of the cells have 42 chromosomes exactly
like normal diploid cells, and the karyotype coincides with that of the
spermatogonial cells (YosIDA 1955). In the regenerating rat liver the
majority of the hepatic cells are of polyploid or alloploid type. Determination of the chromosome numbers in these polyploid cells is very difficult because of clumping of the chromosomes. However, soms cells are
distinctly of the diploid type, and have 42 chromosomes.
The tumor cells of the ascites hepatoma No. 7974 also show a wide
range of variation in chromosome number (30 to 72), with the mode at 48.
Based on a karyological analysis of these cells, it was found that out of
the 48 chromosomes, 29 were rod shaped, and 19 V- or J-shaped (Figs.
A-D). It is a noticeable fact that chromosome No. 30 is large and Vshaped and No. 29 is dot-shaped.
Based on the above investigations, it can be said that the tumor cellsof this hepatoma have a characteristic chromosome complex which is neverfound in normal hepatic cells.

14. Karyological Observation on a Hepatoma
Developed in the White Rat(By Tosihide H. YOSIDA and Takaaki ISHIHARA)

In the course of experiments inducing hepatoma by the administrationof p-Dimethylaminoazobenzen (D.A.B.) in the white rat, a hepatoma
developed in a male. A karyological study of this hepatoma has yielded
the interesting results described below.
The hepatoma developed after the administration of D.A.B. for 150 days.
At autopsy, four tumorous masses were found in four regions of thehepatic lobes, two in the second lobe and two in the third lobe. The
chromosome constitution of these tumors is summarized in Table 1. The
majority of the cells in the No. 1 tumor had a subdiploid complex, whilein the No.3 tumor, cells of subdiploid and subtetraploid complex were
included with almost equal frequency. On the other hand, the No.4
tumor consisted entirely of cells containing a subdiploid chromosome
complex. Karyological analysis of these tumor cells has revealed distinct
V-shaped chromosomes in the cells of the No.2 tumor. No such chromosome was observed in cells of the other tumorous masses. From theseobservations it may be said that the peculiar V-shaped chromosome is
not a necessary constituent of tumor cells.

23

RESEARCHES CARRIED OUT IN 1955
Table 1.

No. of Hepatic
tumor
lobe
No. 1
No. 2
No. 3
No. 4

2nd
2nd
3rd
3rd

15.

Frequency of diploid, tetraploid and hyperploid cells
occurring in the hepatoma.
Frequency

2n
%

29.0
75.0
40.0
96.6

4n

8n-32n

52.0
18.0

19.0
7.0
22.0

38.0
3.3

No. ofcells
observed

Variationin chromosome number

100
100

25-151 (?)

20

27- 78 (41)34-168 (81)

37
16

50
30

0

I

No. ofcells
observed

Observations on Hyperploid Cells in Regenerating
Liver after Partial Hepatectomy of the Rat(By Takaaki ISHIHARA and Tosihide H. YOSIDA)

As is well known, after partial hepatectomy the remaining portion of
the liver undergoes cell regeneration by mitotic divisions. The chromosomesof such regenerating hepatic cells were observed, using our squash technique.
Nine individuals of pure-strain (W, Wistar-King-A, Wyne) and mixedstrain rats were used in this study. The methods and results are shownin Table 1. There are more polyploid than diploid cells. Though theexact chromosome number in the hyperploid cells could not be determined,
it apparently ranged from 8 n to 32 n.
Table 1.

Frequency of polyploid cells in the course of liver restration
after partial extirpation----------_.

Ind. No.
1
2
3
4

Sex

-±:2n

±4n

~

21
45
22

22
110
19
21

if
~

I

>±4n

Total

StrainAge(mon.)

7

50
242

W
W

12
8

50

Wyne

50
37
50

Wyne
WKA
WKA
WKA

5
5
12
18
12

87
9

~

20

5

~

6
7

~

8
9

if
if

16
17
54
9

23
91
22

9
9
10
30
19

15

22

13

175
50
50

Total

219

342

193

75~

%

29

45

26

IOU

--------

~

12

N
mix.

3
4

Hrs. after
operation
48
48
24
72
72
72
48
48

48

24

RESEARCHES CARRIED OUT IN 1955.

Figs. 1, 2. Hyperploid cells occurring in regenerating liver after partial hepatectomy. 1, 8n cell. 2, 32n cell. The two photomicrographs were taken with a" Leitz Mikam" under the same magnification (x 2000).

The relationship between the size of the cell-body and the number ofchromosomes was examined in the regenerating hepatic cells. In 2n, 4n
and 8n cells, increase of cell size is roughly proportional to the chromosome number (Fig. 1). On the other hand, in the case of hyperploid cells(higher than 8n), no further increase of cell size can be perceived. The
chromosomes in these hyperploid cells are slender in shape, something
like daughter chromatids in diploid cells (Fig. 2). These hyperploid cells
are almost the same in size as tetraploid or octoploid cells. It is a noticeable fact that the increase of chromosome number in regenerating hep'l.tic
cells is not always followed by an increase in cell size.
The observations suggest that in a regenerating rat liver there are two
types of polyploid cells, one in which the increase of chromosome number
is accompanied by an increase in cell size and the other in which thisparallelism is not found.

D.

GENETICS AND BIOCHEMISTRY OF THE
SILKWORM AND OTHER INSECTS

16.

Bi-and Uni-lateral Variations in Certain Characters oj
the Silkworm due to Unstable Genes(By Yoshimaro TANAKA)

The author has already revealed that the major genes L (for multilunar
marking) and K (for knobbed) are highly stable, while the modifters
which control the numbers and positions of the multilunar spots andknobs are very unstable and variable. The most important characteristic

RESEARCHES CARRIED OUT IN 1955

25of these modifiers is that they cannot be fixed even after a long-continued
selection, although selection may be effective in many cases. As previously
mentioned (TANAKA 1951), the inheritance of unstable genes is difficult
to analyse on a polygenic basis. The case to be described here is, it
seems, another example which demonstrates the peculiar nature of theunstable gene.

a. .,

-

••

,. ••
•• ••
•• ,

••
A
1
2
3
4

S

e
7

e
9
10

.
I

B

C

F

D

I

H

G

.-,
.
••
••
••• •• •••• .,
••
••
•
•
.,
•• ••
••
••
••
•• •• • •• •• ••- •••• ••• • I I•• ••, ••
....

I'

I

•• •• " •• • "
II

II

"

II
&

V.

J

K

L

M

N

0

p

Q

Fig. 1. Semi-diagramatic representation of the more frequent types
classified by the numbers of large brown spots of multilunar markings.
In counting the numbers of spots, those on the third segment are
excluded as they are common to all types. The numerals on the leftdenote the segment numbers of the larvae.
A: 4-spot type
G, H: 7-spot type
M: 1D-spot type
P: 13-spot type

B, C: 5-spot type
I: 8-spot type
N: ll-spot type
Q: 14-spot type

D, E, F: 6-spot type
J, K, L: 9-spot type
0: 12-spot type

RESEARCHES CARRIED OUT IN 1955

26

Among different multilunar strains, there are some lines in which
10-spotted larvae are usually most abundant (Fig. 1). One of these lines
was selected for the lO-spot type through many generations, and thebi-Iateral variation of spot number has been followed (Table 1). This isa typical case of unstable inheritance.
In another lO-spot line, a similar selection was practiced through anumber of generations, except that some l4-spot individuals wereintroduced to ensure reproduction at two different times. This line gave
almost exclusively, however, offspring with more than ten spots, showing
a uni-Iateral variation towards the plus side (Table 2).
A line of the" knobbed" strains showed for many generations a unilateral variation towards the minus side, when the lO-spot type only,with a single exception, was selected for propagation (Table 3.).
These facts seem to suggest a partial inactivation of variability of
unstable genes, resulting in a stable condition in a plus or minus direction.

Table 1.

Bi-lateral Variation of L-Spots---------~

Lot No.

4

5

6

7

8

9

10

11

12

291s271301s271311s271321s271331s271341s271351s271361s271371s22381s22391s22401s25411s25·421s25431s25441s25

(26)
(27)
(13)
(6)
(13)
(29)
(4 )
(14)
(5 )
(15)
(12)
(14)
(9 )
(14)
(7)
(13)

Note:

1)
2)

24
51
31
70
26
54
5 84
1 112
6
3
30
22
12
31

97
136
133
134
82
68
159
108
40
34
89
77
38
45

13
-

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

512
I
418
I
463
I
315
I
396
I
26
I
168
I
72
I
165
119
I
270
I
323
I
109
I
99
I
176
I
185

68
157
55
41
25
50
5
60
12
59
40
12
43
10
25
19

12
57
5
12
2
28
1
26

6

Total
723
829
694
581
542
299
426
421
227
238
449
434
239
195
205
207

1

1
1
5

2

2

1

17
13
20

14

--------~-

2
1
8

3
1

4
3
~

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

The numerals in the top row represent the spot types.
The numbers in heavy type connected by lines show the spot types
selected for reproduction in successive generations.
3) The figures enclosed by parentheses are the numbers of egg-batchesfrom which the larvae hatched out.

27

RESEARCHES CARRIED OUT IN 1955
Table 2.
Lot No .

..

401161411161
421 161
431161441161451161461161

4

5

6

Uni-Iateral Variation of L-Spots
7

8

(14)
(14)
(14)

3

9

10

11

12

4

133

23

11

7
5

I

190

I

90

I

(13)

194

I

(15)

147

I

(16)

194

I

(14)

97

I

29

6

229

25

4

176

35

10

242

7

3
3

481161

(14)

io

1

69

6

l

208
116

25

3

172

4

125

(5 )

Total

15

(7)

49116114

8471161

I

13

109

2

155
22

3 162(12)

321

240

I

501161(9)77

5

1 I 62( 4)

186

269

5021621

(1)

65

42

36

24

66

233

20

52

46

116

271

15

28

11

49

227

33

66

47

80

253

35

18

2

287

12

18

4

94

28

9

3

221

61

103

108

187

506

112

55

29

17

532

5031621(1)50416212 ( 1 )51116212 (1 )512 I 6212 ( 1 )513 I 6212 ( 1 )514 I 6212 ( 1 )5211175311 17532117

(1)

(5)
(1)

I

37
I

124

I

27
I

232

i

60

I

180

I

47

I

319

I

9

20

46

32

18

i

125

I

5331171.. (1)5411172 ( 2 )For legend see Table 1.

29
1

86

21

55

49

14

168

102

212

65

79

544

RESEARCHES CARRIED OUT IN 1955

28

Table 3 Uni-Iateral Variation of Knobs
Lot No.

4

5

6

7

8

9

10

512 s 312 (1 )

15

26

82

12

4

4

3

513 s 313 (1)24514 s 313 (2)521 k6531 k6

14

10

3

6

12

15

23

41

89

4

(3)

47

541 k6(3)

12542 k6(2)

5543 k6'

(1)

5

10
3
7

R

11

39

59 117

13

14

Total

146
57

I

181

I

498

434

I

210

440

I

20

53

217

309

15

28

250

298

12

30

162

3

55

544 k6 a (2)4551 k6 a (4)2552 k6 a (1)

12

I

18

4

(2)

11

30

9

3

I

464

I

2~9

229
58
468
261

For legend see Table 1.

17.

A new EGa Strain of the Silkworm(By Mitsuo Tsu.J1TA)

Among the F 1 silkworms from thecross £-'/.'/+ x + reared in the third
rearing season of 1951, one apparently new mutant male was found.
This larva had supernumerary crescent patterns on the dorsal side of the
6th segment and lacked the star patterns on the 8th dorsal segment. At
first this was suspected to be an +/EJiC
larva, a type which occasionallyappears by segregation from such across. However, genetic analysis of
A: Larva without crescent or starpatterns
13: Larva with rudimentary crescentpatterns on the 5th seglllcnt•

RESEARCHES CARRIED OUT IN 1955

29

this larva has shown that it was not an EMe but an EGa' (a type of EGa)mutant.
This mutant was crossed to a wild type female, and segregation
occurred in F 1 generation as shown in Table 1.
Segregation in the cross + x double crescents

Table 1.
Mating type+ x double crescent+

Triple crescents*

Double crescents (II)**

267

7

258

* larvae with paired crescent patterns on the 5, 6 and 7th segments.
** larvae lacking the crescent patterns on the 6th segment or having rudimentarycrescent patterns on the 5th segment (Photo. B).

The larvae with the double crescents were sib-mated and three batches
were reared the next spring. Segregation took place as in Table 2.
Table 2.

Segregation in the sib-mating of double crescents

No.

Mating typeI

Double creScerltsx double crescents

2
3

"

*
**

"

i

+ I

Triple,Doublecrescents

100 1- 1 3
48;
90!

DoubleI

Non- **!'~"7;tl""re:~ (II) cr_:",,49

I

115

I

Larvae with paired crescent patterns on the 5th and 6th segments.
Larvae lacking crescent patterns on the 5th and 6th segments (photo. A).

As shown in Table 2, from a batch of sib-matings of double crescents(No.2), three types of larvae appeared; namely, 11 with double crescents(I), 73 with double crescents (II) and 25 without crescents.
Next, sib-matings of the non-crescent individuals yielded a number oflarvae without any crescents or star-shaped markings and also larvae withrudimentary patterns on the 5th segment. By selection· of unmarked
individuals, a line was established in which most of the larvae were of
the same phenotype, lacking in the crescent patterns on the 5th and 6th
segments. So far, however, no strain in which the phenotype of larvae
is entirely uniform, has been obtained.
The larvae without the crescent markings resemble the larvae of strain
Nt, and the larvae with the double crescents (II) resemble the larvae ofEGr. However, homozygous individuals of both types die in a late embryonal stage, exhibiting the characteristics of an EGa embryo.
The EGa/EGa! embryo produced from the cross EGa/ + X EGa'/ + shows

30

RESEARCHES CARRIED OUT IN 1955

the same abnormarity as theEGalEGa embryo.
From these observations, it is clear that the genic constitution of the
non-crescent type is identical with that of EGa. However, there must be
some reason why most of the larvae of this strain lack the crescentpatterns. One possible explanation is that EGa l is somehow different
from EGa which has a characteristic for suppression of the crescent patterns on the 5th and 6th segments, and if these patterns appear, it isapparently due to the presence of several recessive modifiers. Anotherpossibility is that EGa l has the same genic constitution as EGa, but thatthe presence or absence of the crescents depends on modifiers which act
as suppressors or enhancers of the patterns.

18. A No-lunule Mutant in the Silkworm Induced by X-ray Treatment(By Mitsuo TSUJITA)

Female pupae of the genotype HKPIHKp were irradiated with X-raysof 8000 r, and the imagines were mated to normal males. Two exceptional larvae lacking crescent and star markings and having the phenotype Nl (No-lunule), were found among 7346 F 1 individuals. The female
moths emerging from these larvae were crossed with normal males, andthe following segregation was observed:
Nl'

+

Total

HKp

+

HKp

+

79

95

80

100

354

Genetic analysis of this mutant has disclosed that it is homolethal anddeath occurs in the embryonal stage. The heterozygous larvae are viable
and show the characteristic phenotype. In appearance this mutant resembles Nil + discovered by Y. TANAKA, therefore the same symbol, Nl'
may be used. It has been revealed that the gene for this mutant is completely linked to the U locus. No recombinants were obtained from either
the cross UINt' x + or + x UINt'.
The recombination value between odk and Nt' is 4.9, which is higher
than the 2.9 which was estimated for odk and Nl (Tsukushi 1955).
In another experiment the recessive gene oa was used. This is locatedon the XIV chromosome and larvae homozygous for oa have a translucent
integument. Two types of larvae, Nt'l + and normal, segregated from•

31

RESEARCHES CARRIED OUT IN 1955

the cross Nl'/ + x oa/oa. All of the larvae of the former genotype havetranslucent integument and all of the latter genotype have normal integument. It may be inferred from this result that Nt is a deficiency of theregion of the oa locus on the XIV chromosome.
The results of the genetical analysis of Nt' stated above are nearly
identical with the results obtained for Nt by TSUKUSHI (1955). To examine
the genetic relation between Nt and Nt, the cross +/Nt x +/Nt was
made, giving some F 1 individuals of the genotype Nt/Nt. These showedlethality in the embryonal stage. Thus, in genetic constitution Nt can
not be discriminated from Nt.

19. Induction of the Mutants Eca and Nt by X-ray Treatment(By Mitsuo TSUJITA)

The mutant Eca appears spontaneously, though extremely rarely. Nt
was discovered first by Y. TANAKA (1925) as a spontaneous mutant. However, as far as I know, it has never since been found as a spontaneous
mutant. Both of these mutants can be easily induced by X-ray treatment.
In my experiments, some female pupae of the genotype HKP/HKP were
irradiated by X-rays of various dosage as shown below (Table 1).
Table 1. Details of X-rays utilized for experiments-

SeasonKvp

rnA

Distancecm

rjmin

1954 Summer
1955 Spring
1955 Summer

180
180
180

3
3
3

20
40
20

162.44
40.61
162.44

Duration I Tota~dOSage_
min.
49.3
194.6
49.3

8000
8000
8000

The experiments were repeated three times: the results are shown in
Table 2.
Table 2.
!

SeasonProgeny of X-rayed HKpjHKp (if-) x +(1)Exceptional types

No. oftreatedmoths

Nl- Sever:a!--other' Total ofmutants I mutants

l

Total

----------

I

1954summerl
1955 Spring
1955Summer. HKpj+ +

167
230
31

2
20
1

10
16
2

--------

.

21
29
1

33
65
4

7346
29568
204
----

7379
29633
208

32

RESEARCHES CARRIED OUT IN 1955

Mutants were looked for in the stages from the 2nd to 4th instars. It
is possible that some exceptional individuals escaped our notice because the characteristics of the mutants studied are hard to discriminate
in larvae that are too young.
As shown in the above table, several exceptional types were found.
Among these, Eca and NI individuals are commoner than any othermutant. Moreover, these mutants were produced in all three experiments.
NI is a deficiency in the XIVth chromosome. Eca, may be also somechromosomal aberration, perhaps a deletion of the E region of the Vithchromosome. It is noteworthy that most of the mutants induced by Xray treatment are located on either the Vith or XIVth chromosome. This
fact suggests some affinity between these two chromosomes.

20.

Studies on Maternal Inheritance of the Lethal Yellow in the Silkwarm.
Exchange of Ovaries between +/lem! and lem/lem! Larvae.
(By Bungo SAKAGUCHI and Mitsuo TSUJITA)

The maternal inheritance of the yellow lethal in the silkworm has been
described by TSUJITA ('53, '54, '55). To make clear the mechanism of
this peculiar inheritance the present experiments were undertaken.
Fifth-instar larvae with genotypes +/lem! and lem/lem!, which had
segregated from a cross between +/lem and lem/lem!, were used asmaterial. The ovaries of larvae of the different types were exchanged.
Of 630 larvae thus operated on, only 3 survived and had progeny.
The female moths produced from these larvae were mated with male
moths of the genotype lem/lem'. The eggs laid were incubated after
treatment with heated dilute hydrochloric acid, and the larvae homozygous
for the lem! gene were examined. The results may be summarized
as follows.
When the +/fem ' larvae were implanted with ovaries of fem/fem ' , thehomozygous lem! embryos which develop from these transplanted eggs
hatch out as apparently normal, black-colored larvae, but they change
into distinctly yellowish larvae immediately after the first moulting andstarve to death. On the other hand, the lem ' homozygous larvae emerging from eggs laid by the fem/lem ' moth which had received a +/fem 'ovary by transplantation develop into yellowish brown larvae: they, however, die in the egg as they are unable to chew through the chorion.
From these experimental results it may be safely concluded thatlethality is not determined by the genotype (+/lem ' or lem/lem ' ) of theI

RESEARCHES CARRIED OUT IN 1955

33

embryo but by the genotype of the mother's body in which the eggs
develop.
It seems that the maternal inheritance of the yellow lethal characteris due to the presence or absence of some diffusible chemical substancein the ooplasm of eggs produced by the mother moth. This substanceis closely related to xanthopterin-B according to our genetical and biochemical studies of this lethal strain already published.

21. Genetical and Biochemical Studies on the Yellow Lethal Silkworm.
IV.

Changes in Quantity of Pterin Compounds in Explanted Ovaries.
(By Bungo SAKAGUCHI and Mitsuo TSUJITA)In another experiment it has been disclosed that the lethality of larvaeof this type depends on the genotype of the mother, and not on the
genotype of the egg. In order to clarify what substance is directly
concerned with this phenomenon, the following experiments were carried
out.

Wild type (+/lem!) and lemon (lem/lem!) individuals, segregated fromthe cross between +/lem l and lem/lem!, were used as material, transplantions were carried out on larvae in the first or second day of the 5th
instar stage. The ovaries were removed from individuals of genotypes+/lem! and lem/lem! and exchanged by transplantation. When the individuals thus operated on developed to adults, their ovarian tubules were
removed and chemically examined.
The pterins contained in the ovarian tubules were extracted with 30 %acidified ethanol. The solution was fractioned by paper chromatography,
A methyl-enthyl-ketone+propionic acid+H 20 solvent was used as adeveloper for the fraction. The quantitative analysis of pterins was madewith a fluorophotometer.
By this procedure, several fluoresecent substances were identified. A
striking difference was detected in the quantities of isoxanthopterin andxanthopterin-B contained in the ovarian eggs of the operated individualsof the two types as compared with the ovarian eggs of control individualsof the corresponding genotypes. The results are shown in Table 1.
As shown in the table, the effect of the maternal body upon the
production of pterins is very remarkable. When ovaries of the genotype
lem/lem l were transplanted into individuals of the genotype +/lem!, theamount of isoxanthopterin in the ovarian eggs increased remarkably, but
the xanthopterin-B decreased. On the contrary, in the ovarian eggs ofthe genotype +lem! transplanted into larva of the genotype lem/lem!, the34

RESEARCHES CARRIED OUT IN 1955
Table 1.

Quantitative analysis of pterins in the transplanted ovaries(relative value).

+ /Iem!

Ovaries transplanted iOvaries transplanted
lem/lem l .from lemon (lem/lem l ) from wild type (+ /lem l )Ito wild type (+ /Iem!) ito lemon (Iem/lem l )j------

isoxanthopterin

57.0

15.0

42.8

24.2

xanthopterin- B

17.0

30.0

22.0

29.8

amount of isoxanthopterin decreased significantly and that of xanthopterinB increased.
It seems probable from this experiment that the maternal inheritanceof the yellow lethal depends upon the relative amount of isoxanthopterin
and xanthopterin-B present in the ooplasm and that this is controlled by
the somatic cells of the mother.

22. Genetical and Biochemical Studies on the Yellow Lethal Silkworm

v. On Metal Metabolism of this Mutant(By Mitsuo TSUJITA and Bungo SAKAGUCHI)

For the purpose of determining the relation between the phenomenonof maternal inheritance of the yellow lethal character and metal metabolism, further experiments were carried out.
Materials and Methods: Eggs, larvae and imagines of the genotypes+/+, +/lem l , lem/lem l and of the yellow-lethal eggs which segragatedfrom the cross lem/lem l x +/lem l , were used. The material was ashed, andan analysis of metals was made by paper chromatography. In order todetect the metals, such reagents as rubeanic acid, potassium ethylxanthogenate, pyrochatechol and dithyzone were sprayed on the chromatogram.
Experimental results:
1. Detection of metals in various developmental stages. Fe, Cu, Co
and Ni were found throughout the developmental stages up to metamorphosis in the normal strain, and Ti was also detected in the lemon strain.
It was found that throughout development there was a larger amount of
Ti in individuals of the genotype lem/lem l than in individuals of the
genotype lemflem. In the former Cu was not detectable. Thus, among
the +, lem, and lem l strains, the following relations hold regarding therelative amount of Cu and Ti: For Cu there is the relation + lem andfor Ti lem l
lem.

>

>

•

RESEARCHES CARRIED OUT IN 1955

35

2. Experiments with metal injection. Chlorides of metals such as Fe,
Cu, Ni, Co, and Ti were injected into pupae of +, tem and tem l strains,
and the metal elements contained in the eggs laid by the moths emerging from the injected pupae were examined. The results show that all
metals injected into the pupae may be detected, but that they haveproduced no effective change on the phenomenon of maternal inheritanceof the yellow lethal.
Conclusion: From these experimental results, it may be seen that amuch larger amount of Ti is accumulated in the temlflem l individuals
than in individual of any other genotype. This fact seems to indicatethat there is a close relationship between Ti metabolism and the phenomenon of maternal inheritance of the yellow lethal. However, the experiments with metal injection put in doubt the interpretation that the maternal
inheritance of the yellow lethal is only due to the presence of Ti in alarge quantity. More probably, the coexistence of Ti and some othersubstances, and their co-operative action, is necessary for this phenomenon.

23. Photoperiodic Effects of Alternated Dark and Light Phasesof Diapause of Antheraea pernyi(By Yoshimaro TANAKA)

In previous papers (TANAKA 1950, 1951) the author reported that subjected to a short day (less than 13 light hours) Antheraean pupae
hibernate, while with a long day (more than 15 light hours), if the wholelarval life is exposed to the same photoperiod, all pupae become nondormant without exception.
In recent experiments larvae were exposed to intermittent light anddark phases of fixed duration during the period from hatching to cocooning in the second culture of 1955.
Experiment I. 2-hour light and I-hour dark phases alternated.
Experiment II. I-hour light and 2-hour dark phases alternated.
In Exp. I, where the total light hours per day were 16, 2.5% pupae hibernated; thus the long-day effect was apparent. In Exp. II, there were 8
total light hours per day, but the hibernation frequency was only 12.15%.
This seems to mean that the short-day effect cannot be perfect when thedark phase is interrupted by a light phase so frequently.
Similar experiments with different durations of light and dark phases
were made in the third culture.
Experiment I. 2 1/z-hour light and liz-hour dark phases alternated.
Experiment II. liz-hour light and 2 1/z hour dark phases alternated.

36

RESEARCHES CARRIED OUT IN 1955

The total light hours were 20 in Exp. I, and 4 in Exp. II, the hibernation frequencies were 8.55% and 42.3%, respectively.
From these results we may conclude that a continuous illumination of
4-13 hours is indispensable for a perfect short-day effect, but the longday effect is not much affected by intercalary darkness.

24. Genetical and Biochemical Studies on pteridine Metabolism.
(By Saburo NAWA and Toshifumi TAIRA)

It has been found previously that the red eye pigments of Drosophiia
melanogaster are closely related to pteridine o . The yellow pigment
found in the eye of the mutant strains se and cl has been identified as
xanthopterin·BO which has the structure N8-l a ctyl-7, 8-dihidro-2-amino-4hydroxypteridine·6-carboxylic acid 2 ).
In the eyes of the double mutants v; se and v; cl there is accumulationof xanthopterin-B, so that the scheme:
xanthopterin-B--[ - - ? - red pigments(se, cl)can be suggested.
The body of strain sed contains a larger amount of yellow pigment anda smaller quantity of isoxanthopterin than do the bodies of other strains.
This yellow pigment in sed has been identified as xanthopterin-B by examining the Rf value, fluorescence, ultraviolet absorption spectra andchemical properties. It has been found that there is an accumulation ofxanthopterin-B and an inhibition of isoxanthopterin production in the bodyof the double mutant, cn; sed. Such a relationship has also been foundin the lem mutant of the silkworm. Thus the scheme:
xanthopterin-B - \ -,.. isoxanthopterin(sed, lem)may be proposed.
To examine the interrelationships among xanthopterin-B, isoxanthopterin
and the red pigments some in vitro experiments have been carried out,
but no clear results have been obtained so far.

1) NAWA, S. and TAIRA, T. 1954. Proc. Japan Acad. 30:632.
2) FORREST, H. S. and MITCHELL, H. K. 1954. J. Am. Chern. Soc. 76:5658.

RESEARCHES CARRIED OUT IN 1955

37

25. Biochemical Studies on the Hibernating Character in the
Chinese tussah Silkworm, Antheraea pernyi. II. The Roleof Sugar Metabolism in Hibernation.
(By Bungo SAKAGUCHI)TANAKA ('41-'43, '50-'51) has found that photoperiodism plays the mostimportant role in inducing hibernation of the Chinese tussah silkworm,
Antheraea penyi Guer. As reported in the first paper of this series,
there is slight difference in the respiratory emzyme system between
hibernating and non-hibernating pupae of this insect.
a) The effect of an artificial supplement of sugar on hibernation.
The present experiments were undertaken to explore the response ofhibernating and non-hibernating pupae to sugar supply. Hibernating
larvae in the middle stage of the 5th instar, obtained by photoperiodic
treatment of the eggs and larvae, and non-hibernating larvae were kept
for four days in the presence of an artificial supply of 0.88 M sucrose
solution. Then the number of days required to pass from pupa to imago
was recorded for hibernating and non-hibernating larvae. Of the 20
pupae derived from hibernating larvae, 9 developed imagines in 30 to 40
days, 4 to 60 days, and 3 remained in hibernation. On the other hand,the non-hibernating larvae thus treated did not develop into hibernating
pupae in spite of the sugar supplied. Consequently, it may be concluded
that sucrose has some effect on the hibernating character.
b) Detection of sugar in the blood of larvae with different hibernating
characters.
On the basis of the above results, and to further examine the relation
between the hibernating character and sugar metabolism, further experiments were undertaken. Sugar was obtained by acid hydrolysis of theblood of 5th instar larvae and examined by paper chromatography. The
chromatograms were run with butanol + acetic acid+H 20 or phenol andsugars on the paper were detected by the reaction of an aniline chloride
solution.
Sucrose, galactose and glucose were distinctly detected in the blood of
non-hibernating larvae, while only traces of these sugars were found inhibernating larvae. In the latter some unknown substances related tosugars with an Rf value of 0.2 were detected by a solution of phenol orbutanol+ acetic acid + H20.
It is likely that there is a close relationship between hibernation andsugar metabolism, and that sucrose is factor effective in controlling thehibernating character. LIVERMAN and BONNER (1953) reported that sugars

38

RESEARCHES CARRIED OUT IN 1955

(glucose, sucrose, galactose) and Krebs cycle intermediates (citrate,
malate), even without illumination of high intensity, affected the photoperiodism of Xanthium pensylvanicum. My previous (1955) and present
results, which show a physiological relation between photoperiodicity and
the Krebs cycle or sugar metabolism, confirm these findings.

E.

POPULATION GENETICS OF SOME INSECTS
AND A LAND SNALL

26.

Population genetics of a ladybeetle and a land snail.
(By Taku KOMAI)

A short paper on an actual instance of microevolution observed in a
population of the ladybeetle, Harmonia, inhabiting Suwa (Ann. Rep.
Nat. Inst. Genet. 5: 37-38) was read before the Symposium on Population Genetics held at Cold Spring Harbor, June 6-13. A review, "Genetics of ladybeetles " was completed for Advances in Genetics vol. 8. A
paper by Komai and Emura, "A study of population genetics on thepolymorphic land snail, Bradybaena similaris", was published in Evolution(vol. 9, no. 4: 400-418).
The records of the results obtained by studies of population genetics
with various materials, which had been carried on during the period
1951-1953 in cooperation with a group of investigators, were completed in
the current year and published in a book entitled "Syudan Idengaku(Population Genetics)" from Baifukan, Tokyo. The book contains thefollowing articles by Komai:"Population genetics of the lady-beetle, Harmonia axyridis" (pp. 46-60),"Population genetics of the land-nail, Bradybaena similaris" (pp. 6176)," Population genetics of two species of butterflies" (pp. 77-83).
Some supplementary experiments on the capacity of tolerance foradverse temperature and humidity of Harmonia and Bradybaena wereconducted. A small sample of a population of Harmonia was obtained
from Taipei, Formosa. This consisted entirely of the type consPz"cua, andsuggests a closer affinity of this population to populations of the same
species in Kyusyu, rather than to those of Middle China.

39

RESEARCHES CARRIED OUT IN 1955

27. Population Genetics of Balanced Polymorphism
in Drosophila rufa.
(By Toshifumi TAIRA)

The female of this species is distinctly dimorphic. The" dark" typehas a dark band on each abdominal segment, much like the malemelanogaster. The" light" type has no such band, so that it resembles
the female melanogaster. The male is monomorphic. The dark marking
in the female shows complete dominance over the light marking.
The result of analysis of this polymorphism is reported in SyudanIdengaku (edited by T. KOMAI and K. SAKAI, 1956). The relative adaptive
value of different genotypes in natural populations has been shown to be
Did> DID> did. In laboratory populations in an equilibrium state,started at various initial proportions of each genotype and kept at 25°C,
the relative adaptive value is D/d> did> DID. This relationship is kept
when the population making up an equilibrium state is moved from 25°C
to 18°C.
Our experiments have revealed that the difference in the relative adaptive values of the two homozygotes in the populations studied is apparently due, in part, to the fact that DID has an advantage over did in mating,while did is superior to DID in the competitive viability of the larva.
The experimental results, however, are not sufficient to completely
explain the difference between these relative adaptive values in the two
populations in natural and laboratory. Our observations on natural populations have also shown that did has some advantage over DID in the spring
time, while it has some disadvantage in the summer, suggesting that did
is better fitted to low temperatures than is DID.
Further experiments, one concerning the effect of population density,
the other on the effect of low temperature on the two homozygotes, werecarried out. The results are presented in Tables 1 and 2. The initial
populations contained the dominant (D) and recessive (d) genes in equal
proportion. The process of change of the proportion with time is shownin these tables.
Table

1.

Frequency of did individuals in large populations
-----

Days

0

61

122

153

187

240

25°C

.50

.34±.014.28± .013.25± .027.29± .014.32± .016

18°C

.50

.66± .014.51± .018.62± .019.42± .049.49± .016

40

RESEARCHES CARRIED OUT IN 1955
Table
Days
25°C
18°C

2.

Frequency of did individuals in small populationso24.34 ± .025

.50
.50

38

75

45
.27±.016.36±.022.41±.013

155.25±.008.49±.012

The large populations, one at 18° and the other at 25°C, differ in thefrequency of did individuals. A similar difference may be found between
two smaller populations, one at 18° and the other at 25°C also.
These data suggest that did has an advantage over DID either in vitality or competitive ability, or both. This seems to be the main reason
why did is always maintaind in a frequency higher than DID, in spite of
the inferiority of did in mating, both in natural spring populations andin laboratory populations.

28.

Variation in the Elytral Pattern of Convergent Lady-birds(Hippodamia convergens) collected in Colorado(By Tosihide H. YOSIDA)

Specimens of the convergent lady-bird (Hippodamia convergens) werecollected in Fort Collins, Colorado, in June, 1952 by Dr. S. MAKINO of
Hokkaido University, who was then travelling in America. The specimens were sent to me for examination of variation in the elytral
pattern.
Table

1.

Variation of the elytral pattern in convergent lady-birds(Hippodamia convergens)
Class
Total

AuthorYOSIDA(1955)KELLOGG & BELL
(1904)

A

B

C

D

498
(86.1 %)

1
(0.2)

79
(13.6)

0578(99.9)

27

70
(6.8)

38
(3.7)

1035
(99.9)

900I(86.8)_1-=~~_

Remarks: Class A represents the normal type having 12 modal spots on each
elytron. Class B is a type having some coalesent spots. Class C is of typewith some spots lacking. Class D is of a type having more than 12 modal
spots.

The results obtained are summarized in Table 1, together with thedata obtained by KELLOGG and BELL (1904) on material collected at Palo

RESEARCHES CARRIED OUT IN 1955

41

Alto, California. Considerable difference in the mode of variation of theelytral spots may be found in the two sets of data. Generally speaking,the beetles inhabiting Colorado have smaller spots than those from California. It is likely that this difference is correlated with the difference inclimate in the two localities. SHULL (1944) has carried out crossing experiments between spotless and spotted convergent lady-birds. From thedata obtained, he has concluded that there is a spotless gene which isalmost completely dominant over the gene for spotting, as well as somemodifying genes. The difference in the frequency of spotless individuals
is mainly due to the difference in the incidence of the gene. He has
found that the material from Colorado has the spotless gene in 6-7 percent of the individuals while the California material has it in only 2
3.5 per cent, and the modifiers are nearly three times as frequent inColorado as in California beetles. The present material confirms SHULL'S
findings in the frequency of spotless individuals.
KELLOGG, V. L. and R. B. BELL 1904. Studies of variation in insects. Proc.
Wash. Acad. Sci. 6: 203-332. SHULL, A. F. 1944. Inheritance inlady beetles
II. The spotless pattern and its modifiers in Hippodamia convergens andtheir frequency in several populations. Jour. Hered. 35: 329-339. YOSlDA,
T. H. 1956. Variation in elytral pattern of the convergent lady-birds (Hippodamia convergens) collected in Colorado. Annot. Zool. Japon. 29: 101-103.

F.

GENETICS AND CYTOLOGY OF RICE

29. Polygenic Nature of the" Gametic·Development Genes" in Rice
(By Hiko-Ichi OKA)

The sterility found in hybrids between cultivated varieties of rice canbe explained by assuming duplicate genes for gametic-development which,if both are recessive, cause deterioration of the gametes carrying them.
The results of analyses for these genes carried out by the writer havebeen published in the Annual Report of 1954 (p. 40) and in the Japanese
Journal of Breeding (2:217-224 & 3:23-30). The experiments consisted ofa crossing of an "(A x B) x C"* design, where a clear segregation offertile and semi-sterile plants takes place. By postulating one or two setsof duplicate Gametic-development (G. D.) genes, the behavior of progeny
with respect to sterility can be successfully accounted for. In some ex-* Varieties A and B are closely related, but differ in fertility in the hybrids
with the third variety C.

RESEARCHES CARRIED OUT IN 195542

periments of this type, however, cases have been found in which the distribution of the percentage of good pollen has several modes. In thesecases an exact analysis of the responsible genes is rather difficult. Nevertheless, by assuming several sets of G. D. genes, the observed frequency
distribution of good pollen percentages can be fitted to the expecteddistribution.
In the F 2 , the percentage of good pollen, as well as of seed setting,varies from plant to plant in a continuous series. Exceptional cases
may be found, as shown in Table 1. Here plants with pollen fertility of
95-90%, 75-70%, 55%, 40% and 30% appeared in an apparently discontinuous series. These values seem to correspond to the theoretical values:
1, 0.75, 0.75 2 ••• 0.75k , which are to be expected when k sets of G. D.
genes segregate independently.
In the present case, the observed
frequency distribution may be fitted to the expected distribution by assuming five sets of G. D. genes.
Table 1. An example of discontinuous distribution of pollen fertility
in the F 2 (from a cross between two Philippine varieties belonging
to the" Tropical·Insular group". 219 x 218).
95 90 85 80 75
Obs. 2
Exp.

6
8
5.68

% of good pollen
70 65 60 55 50 45 40

35

163

1

246
13
14.10

1

10
14.15

2

5
8
7.05

30 25 20

15

2

1

~--

1

.. -----

3
1.81

Num. ofplants43

X2 =3.19
0.22 P>0.30

The results of the observations given above seem to indicate that distantly related varieties of rice generally differ from one another withrespect to several G. D. gene sets. Since these sets exist in multiplicity
and control fertility, which is a quantitative character, they may be con·sidered polygenes. The variation in fertility due to the G. D. genes may
be computed by the formulas given in the Annual Report of 1954 (p. 42).

30. Restriction of Gene Recombination in Hybrid Populations of Rice
(By Hiko·Ichi OKA)

In hybrids between distantly related varieties of rice it is often foundthat the recombination of indepehdent genes is restricted to some extent.
It was stated in the Annual Report of 1954 (p. 47) that this tendency,
found in the F2 , could be explained by the effect of a set of G. D. genes.
For a similar tendency appearing in later generations, however, a geno'

RESEARCHES CARRIED OUT IN 1955

43

typic difference in propagation rate and other causes may be responsible
in addition to the effects of G. D. genes, in the same manner as in thecase of the change of gene frequency in hybrid populations (Jap. Jour.
Breed. 5:207-212 and Ann. Rpt. Nat. Inst. Genet. 5:45-47.
Concerning the G. D. genes, the frequencies of different genotypes in
X2
the F n of a hybrid, Xl X__, may be found from the following formulas:
Xl

.

2

1

Xl X2

1

1

4-2n - +4(3n - =Ul

Xl X2

l

Xl X2

Xl X 2

Xl X2'

Xl X 2X l X 2X l X 2

Xl X 2 '

Xl X2

2)

311
8 -zn+S(3n':: 1 )=U2
1 ----1 =Ua

2n - l3n - l

By using these formulas it will be shown that with repeated inbreeding
Ua and U4 approach zero, while Ul and U2 come near 1/4 and 3/8 respectively. Thus, when two pairs of genes, A-a and B-b, are linked with
Xl-Xl and X2-X2 respectively, recombination between A-a and B-b, isrestricted to some extent, although these genes are independent. In
this case, recombination between X1"Xl and A-a, and between X2-X2 andB-b, is not disturbed by gametic selection. The frequencies of different
combinations between A-a and B-b may then be computed from the valuesof Ul to U4 and from the frequency of recombination of two linked genes
as shown by the formula of Neider (Heredity 6: 387-397, 1952).
Next, we may consider a case in which different genotypes for two independent genes, A-a and B-b, differ in propagation rate. As mentioned
in the Annual Report of 1954 (p,45), the propagation rate of the heterozygotes will not greatly influence the frequencies of those genotypes. If
recessive homozygotes AAbb, aaBB and aabb have propagation rates P, q
and r respectivety, the relative frequencies of different genotypes in the
F n will be shown by the following formulas:
AaBb

1
4 n- l

AABb, AaBB

-1 -

AABB

111
- - n + -n

2n
4

1
22n - l--_._--~-

2

4

}

1
1
1
CAB) -+--+4 4 n 2n

44

RESEARCHES CARRIED OUT IN 1955

_ 1---=~2P)~~12n 12 - (1-2P)(2n - 1-l){1-(2P)'z-l}4n(1-2P)

Aabb
AAbb

l--=-(~q)n-l

aaBb

22n - 1(1-2q)(2n~1_1){l=(2q)n-l}aaBB4n(1-2q)aabb(ab)

1

(Ab)

l

(aB)

1-(4r)n-l + 2P{~ _(2p)n-2 L
4n(1-4r)
4n(I-4r)(1-2p)+_~lJD~(2q)n-2}4n(I-4r)(1-2q)(~'.::1+ 1){I-(2p)n-l}4n(1-2P)(2 n - 1 ·t 1){I-(2ql'~1}4n (I-2q)
2p·4r{(4r)n-.~~(2P)'Hl

4n(I-4r)(4r-2p)
2q ·4r{(4r)'H_(~lJ)'H}
4n(1-4r)(4r-2q)

Two varieties of rice, 414 (a "Continental" variety, non-glutinous, with
red seed coat) and 563 (a "Temperate-Insular" variety, glutinous, withcolorless seed coat) were crossed, and the hybrid was propagated in bulk
without selection. In the seeds of the generations from F 3 to F 7 , thefrequencies of different combinations of the glutinous gene (+: gl) andthe seed coat color gene (Rc: rc) were observed. It has been found thatthe parental combination groups (+ Rc and gl rc) tend to increase in successive generations at the expense of the recombination groups. By computing the values of several parameters for the G. D. genes and the
propagation rate by using the above formulas, it has been found that theobserved frequencies of different combination groups comform well tothe expected frequencies.
In populations of hybrids between distantly related varieties of rice,
the tendency to restrict gene recombination is observed not only for the
major genes, but also for genes controlling various physiological characters. This tendency seems to be largely attributable to such geneticalmechanisms as mentioned above.

31.

Inheritance of Several Agronomic Charactersin a Varietal Hybrid of Rice
(By Hiko-Ichi aKA)

Two distantly related rice varieties, Pei-ku and Taichung no. 65, werecrossed in Taichung, Formosa, and the inheritance of heading date, panicle number per plant, height, panicle length and grain number per panicle were investigated by statistical-genetic methods.
" Pei-ku" is a

RESEARCHES CARRIED OUT IN 1955

45

Formosan native variety of the first-crop nature, belonging to the socalled Indica or "Continental" group; "Taichung no. 65" is a representative of the" Horai" variety belonging to the Japonica or " TemperateInsular" group. The outline of the experiment is as follows: F 2 to F 5bulk populations, propagated without selection, were grown in the second
crop of 1953, and about 40 plants were randomly selected from each population. In the first crop of 1954, families raised from these seeds,
together with the families belonging to the F 2 and parental varieties,
were observed in an experiment of randomized blocks design. Measurements were taken on a single plant basis for each character.
For each character, the partitioning of variance components (D, Hand
E items) was conducted first by Mather's method (1949) using the data
for F 2 and Fa. The covariances between characters were also partitioned
in the same way. The principal conclusions reached are as follows:(1) Scale: Both the convenient and logarithmic (starting from thelowest limit of variation) scales were used for all of the characters, andthe scale with the smaller mean square of deviations of observed fromexpected values was chosen. It was found that the convenient scale wasbetter for dealing with heading date and panicle number, while thelogarithmic scale was more suitable for height, pancile length and grain
number. The last three characters seem to be subject to a strong influenceof gene interaction.
(2) Linkage: For each character, the significance of the effect oflinkage was tested by Mather's method (comparison of the sums ofsquares of deviations of observed from expected values, calculated including and excluding ~'3)' Linkage was not apparent in heading date andpantcle number, but it was highly significant in height and grain number,and seemed to affect panicle length, to some extent. Since in thesecharacters the heritable portion of V Fa was larger than half of that ofV F2 , the linkages seem to be mainly of the repulsion phase.
(3) The effect of competition: It was stated in the Annual Report of1954 (p. 54) that the effect of intergenotypic competition should be considered in partitioning variance components for panicle number. The
same conclusion was reached in the present experiment.
(4) Heritability: Considering the problems of scale, linkage and competition as mentioned above, the values of D, Hand E components were
calculated for each character, and the values of heritability (for'P2 individual selection) were estimated. The results are as follows:
Heading date
Panicle numbler per plant..............

0.823
0.090

46

RESEARCHES CARRIED OUT IN 1955
Height................................
Panicle length
Grain number per panicle

0.317
0.237
0.302

(5) Genetic correlation: The values of D, Hand E components were
estimated by covariance between characters, excluding the mean covarianceof Fa families in the same manner as in the linkage test. The correlation coefficients due to D. Hand E components, i. e. correlations due tofixable heritable variation, to non-fixable heritable variation and to environmental variation respectively, were then computed. The results are
as follows:
Heading Date

Height- Panicle Number"
Height- Panicle Number- Panicle Length"- Grain Number"
Panicle Length - Grain Number

rD
0.613
0.405
-0.492
0.568
0.621
0.346

rH
0.870
-0.706-0.340
0.627
0.223
0.208

rE
-0.187-0.391
0.409
0.288
0.406
0.565

32. Observations on Natural Populations of Formosan Wild Rice
(By Hiko-Ichi OKA)

In Formosa, wild rice is found only in one locality, Patu, Tao-yuan
Prefecture (northern part of the island). It has n= 12 chromosomes, andcan be hybridized easily with the cultivated rice; the F 1 shows no disturbance in chromosome pairing. This wild rice has thus been identified
to be a variety of Oryza sative sPontanea. It has, however, many features
sharply distinct from the ordinary cultivated varieties of rice: It is aperennial weed, growing in the water of natural streams about one meterin depth. Important morphological characteristics are: very long antherand awn, and anthocyanian pigmentation in various parts of the plant.
The seeds drop before maturation, and germinate after a dormant periodof more than one year. The population of this plant continues floweringfrom spring to autumn. The flowers are open for several hours, and theemission of pollen occurs 3.9±2.5 minutes after the opening of glumes(in October at Taichung).
To find the frequency of natural hybridization, several plants of thewild rice were planted in the center of eight surrounding plants of aglutinous variety. Seeds were gathered from the panicles of the wild
plant which flowered at the same time as the surrounding plants, andthe frequency of glutinous heterozygotes in the offspring was determined.
The frequency of natural hybrids was found to be 30.7%. The wild rice

lRESEARCHES CARRIED OUT IN 1955

47

is by no means a s¢lf-fertilized plant.
Next, descendents of some twenty plants selected at random from thewild populations were examined. Most of them were found to be heterozygous for leaf sheath coloration, apiculus coloration, phenol reaction andother monogenic characters. Regarding quantitative characters such asheading date, height, and awn length, a wide range of variation was
found within lines as well as between lines. The wild rice thus seems
to be heterozygous for numerous genes. This heterozygosity is p03sibly
due to the accumulation of mutations and to hybridization with thecultivated rice. The population of wild rice seems to have a great storeof mutant genes. It is possible that if these mutants were properly accumulated and combined, genotypes similar to those of cultivated varieties
would be produced.
Table 1. Individual variation among populations of wild rice inlength-width ratio of grain.
Populations

Ratio of length to width
2.702.853.003.153.303.45 3.60

Num. ofplants

Mean

13
16
21

3.12
2.87
3.34

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

A

1

2

3

B
C

4

7

4

1

2

3
1
2

2
3

1

11

2

Differences among natural populations of the wild rice were examined.
Comparison of three populations, located about two kilometers apart andseemingly isolated from one another, yielded significant differences withrespect to awn length, panicle shape, grain shape and other characters.
As an example, the data for the length-width ratio of the grain arepresented in Table I. Since these three populations are under comparable
conditions and the shape of the grain is a character relatively immune toenvironmental conditions, the differences found among the populations
indicate the presence of genotypic differences. The distribution of thewild rice in Formosa is now limited to a small area. If its range covereda wider area, greater difference among populations might have occurred.

33. Karyology of Oryza sativa L, 1. Karyologicalstudies on haPloid rice
(By YO TAKENAKA, Chao-Hwa HU, and Tuguo TATEOKA)
Meiotic studies of haploid rice have been reported by MORINAGA and
FUKUSHIMA (1932, '34), NAKAMURA (1933) and RAMIAH (1934). MORINAGA
and FUKUSHIMA gave no account of the presence of bivalents or other

48

RESEARCHES CARRIED OUT IN 1955

chromosome associations in their first report. In their second report,
however, they mentioned the presence of one or two chromosome pairs
in some pollen-mother cells, and assumed them to be artifacts.
In four varieties of cultivated rice, we found in many pollen-mothercells in diakinesis or first anaphase, the so-called secondary association
among the univalents as well as among a few bivalents. Aside fromsecondary associations, we have found 64 % pollen-mother cells withunivalents only, 3396 with one bivalent and 2 % with two bivalents;
rarely, we even found cells with three bivalents or one or two trivalents.
MORINAGA and FUKUSHIMA observed loose pairing of meiotic chromosomes
in 27.4 % of the pollen mother cells. Observations on the frequency ofbivalents in our material are in good agreement with these authors.
When the types of chromosome association are classified without discriminating between true pairing and secondary association, the chromosome configurations found varied from 12(1) to 5(2)+2(1) with the modeat 2(2)+8(1) during diakinesis, from 12(1) to 2(3)+3(2) with the mode at
1(3)+3(2)+3(1) during dia-metaphase, and from 12(1) to 2(3)+3(2) withthe mode at 3(2)+6(1) during meta-anaphase. The highest association
found was 5(2)+2(1) at diakinesis, while that at dia-metaphase or metaanaphase was 2(3)+3(2). The chromosome affinity appeared to increase
from diakinesis to first metaphase and then to decrease from first metaphaseto anaphase.
In the meiosis of diploid rice, SAKAI (1935) found secondary associations
between bivalent chromosomes, ranging from 1(2)+10(1) to 2(3)+3(2)with the mode at 1(3)+3(2)+3(1). NANDI (1936) and OKUNO (1944) also
obtained results which agreed fairly well with SAKAI'S.
Our results with respect to secondary associations are in full agreementwith those of the above three authors. From their findings, these authors
assume that the basic chromosome number of rice is five. We share thisopinion and assume the secondary association to be due to residual homology.
Thus the chromosome set of rice may be shown to be abcde a'b' c'd' e'
al/bl/.

G.

GENETICS AND CYTOLOGY OF BARLEY,
WHEAT AND AGROPYRON

34. Nullisomic Dwarfs and Tetrasomic Giants in Hexaploid Wheat(By Seiji MATSUMURA)

Dwarf plants possessing 40 chromosomes (20 n), found among the off-

49

RESEARCHES CARRIED OUT IN 1955

spring of the pentaploidhybrid, Triticum polonicumx T. Spelta, arenullisomics, deficient in a chromosome pair of the D-genome. As it is
the a-g-chromosome in the D-genome which is missing, they are called
a-g-dwarfs. From crossing experiments it has been determined thatSEARS' Nulli-XVI and XVII correspond to the f- and c-dwarfs, respectively.
From the results of a nullisomic analysis in the F" of hybrids between
a-g-dwarfs and T. compactum, it has been concluded that the gene forcompactum, C, is located on the e-chromosome of the D-genome.
The gigas-plants with 42 chromosomes (I Iv + 19 II ) found among theoffspring of nullisomic dwarfs are called a-g-gigas, according to theoriginal 7 different a-g-dwarfs. They rtIay be called D-nulli- and AB
tetrasomics. It has been assumed that the suppernumerary A-genome
chromosomes, aA in a gigas and CA in c-gigas, are the same as SEARS'VII
and III respectively, while the additional B-genome chromosome, f ll , inf-gigas corresponds to SEARS' I.

35.

Karyotypes of DiPloid Agropyron Species(By S.

MATSUMURA and S. SAKAMOTO)

It has been inferred from previous result obtained by the senior authorthat the genome possessed by Agropyron glaucum (2n=42) and A.

I
i

.,

,\
f<

Fig. 1
Fig. 2
Fig. I: Sumatic chrumosomes of J1. triticeum.
Fig. 2: Sumatic chromosomes of A. elongatum.

50

RESEARCHES CARRIED OUT IN 1955

elongatum (2n= 70) which is homologous with one of the genomes in
Triticum, is the B-genome (MATSUMURA 1949). According to the hypothesisof McFADDEN and SEARS (1946), A. triticeum, an annual plant having 14
somatic chromosomes, should have the B-genome. We are sceptical about
this hypothesis.
It is established beyond doubt that all chromosomes of the B-genome
in wheat have median or submedian constrictions. But all the 7 chromosomes of A. triticeum show subterminal centromeres, as shown in Fig. 1.
The diploid A. elongatum (2n= 14) is an interesting plant in having
chromosomes with median or submedian constrictions (Fig. 2).

36.

Agropyron and Related Genera Collected in Nepal(By S. MATSUMURA and S. SAKAMOTO)

During the Japanese Expedition to the Himalayas, 1952-53, three speciesof Agropyron, two of Elymus and one of Brachypodium were collected.
Agropyron semicostatum NEES. seems to have the widest distributionof all the three species of the genus. It is tetraploid (2n= 28), and isquite different from A. tsukushiense (HONDA) OHWI which was formerly
included in A. semicostatum NEES. The latter species, which is of thewidest occurrence in Japan, is a hexaploid (2n=42), while A. ciliare(TRIN.) FRANCH. which is distributed throughout Japan, is a tetraploid(2n= 28). In general, the ear morphology of A. semicostatum resembles
that of A. ciliare, but the single spikelets of the former species arerather similar to those of A. tsukushiense. Our cytological and morphologicalobservations sustains OHWI'S classification of these species. Agropyron
Gmelini (LEDEB.) SCRIBN. et SMITH is also a tetraploid (2n=28), and its
morphology is similar to that of A. semicoslatum. Both species belong
to Section Roegneria. Agropyron striatum NEES. shows distinction in
the shape of its spikes from the species mentioned above.
Elymus dahuricus TURcz. and E. sibiricus L. are hexaploids (2n= 42).
They are similar in external morphology, and are widely distributed in
the Far East including Manchuria and Korea.
Brachypodium sylvaticum BEAUV. var. lozoniense HARA is diploid (2n= 18).
Its somatic chromosomes are very small compared with those of Agropyronand Elymus. There is a distinct difference between Brachypodium andAgropyron or Elymus in the basic chromosome number, which is 9 in
the first genus and 7 in the other two genera.

RESEARCHES CARRIED OUT IN 1955

51

37. Off-tyPe Plants Observed in a Wheat Variety, " Saitama No. 27 "(By Kanji GOTOH)

It is well known that various kinds of off-type plants or rogues occur
in some varieties of wheat and oats. In few cases, however, the causeof the appearance of such abnormalities is fully understood, and they
are often considered uncontrollable genetic changes. Rogues are known
among our wheat breeders. to occur occasionally in field populations of
the wheat strain, "Saitama No. 27".
My preliminary experiments on this variety disclosed that except for
the D strain of the variety, which contained 88 % of tall-type plants ofwinter habit, no difference could be found in all the agronomic characters
examined among the 4 strains used in this experiment. In the strains
other than D, tall and low off-type plants were rarely found.
The experiments performed in 1953 and 1954 on D showed that there
was a wide range of variation in plant height, ranging from 84 em to
135 em, and also a striking variability in the date of heading, ranging
from April 14 to 28 in 1954. The data obtained in these two years
suggest that these variations are probably governed by polygenes.
The response of the winter-habit lines of the D strain to a long-day
condition was examined in plants kept in a phytotron maintained at 20°C.
Under these conditions the earliest line attained the booting stage in 61
days after seeding, and the other lines followed, their development
extending over more than 1 month. The normal plants of this variety
were of a spring habit, and they began to produce the uppermost leaves
27-30 days after seeding. According to the number of days from seeding
to the booting stage, all the winter-habit lines were classified into 4groups. The means for each group were calculated for culm length in
the 1953 crop and for heading in the 1954 crop under field conditions.
Thus, it was found that the later groups among the winter-type strainstended to exhibit relatively longer culms and to produce ears later thanthe earlier groups. The differences in both characters among the 4 groups
were statistically significant at the 1 % level. The presence of suchvariability suggests the complexity of the mechanism controlling thisabnormality.
GOTOH, K.

Jap. Jour. Genet. 31., (in press).

52

RESEARCHES CARRIED OUT IN 1955

38. Polygenic Differences in Agronomic Characters among Some
Local Strains of a Barley Variety, "Hakata No.2"(By Kanji GOTOH)

Polygenic segregation in agronomic characters during the period ofmultiplication may be of minor importance from the practical view-point.
However, the problem as to how natural selection affects the polygenic
characters of cultivated varieties may be of some interest from a theoretical
viewpoint. In order to obtain some information on this problem and to
throw some light on the effect of natural selection upon a cross-bredvariety, five local strains of a two-rowed beer barley variety, "Hakata
No.2" were examined comparatively.
On visual inspection, the botanical features of all the five strains appear
similar, and all differences found among them are of a statistical nature.
Among the local strains the differences in culm length, ear length, numberof spikelets on one side and weight of 1000 grains have proved to bestatistically significant; it is suggested that these differences are governedby polygenes.
According to the frequency distribution of ear length and number of
spikelets, the ear length is shorter and the number of spikelets smaller
in local strains derived from northern localities than in southern strains.
This relation largely represents a latitudinal cline.
The results of these comparative experiments indicate that the original
population of "Hakata No.2" was probably heterozygous with respect
to several polygenic characters, especially ear length, and that variations
were released through polygenic segregation in the progeny. It is assumed
that the variation found in these characters among the local populations
is due in large measure to natural selection under different environmental
conditions.
GOTOH, K.

39.

lap. lour. Genet. :n., (in press).

Population Structure of the Barley Variety," Iwate Mensury No.2"(By Kanji GOTOH)

In order to confirm the conclusions derived from the data for "Hosogara No.2" (GOTOH, '55-a, -b), the population structure of the local
strains of another mixed barley variety, "Iwate Mensury No.2", wasanalyzed in the same manner as for the " Hosogara No.2".

RESEARCHES CARRIED OUT IN 1955

53

Five population samples obtained from three northern localities (A, B,e) and two from southern localities (D, F) were compared for culm

length, ear length and grain yield. The differences found among thesesamples are statistically significant. It has been found that these local
strains have distinct genetic constitutions in regard to 3 marker genes:
5 s, governing long or short rachilla hairs; Hs hs, governing presence orabsence of hairs on the basal leaf-sheath and Wh wh, governmg winteror spring habit. 7 of the 8 genotypes expected from all the possiblecombinations of these 3 sets of marker genes were actually found in the
5 local strains examined.
Furthermore, 6 genotypes were discriminated in the A population which
is apparently closely related to the original population, in regard to thedate of heading (ranging from April 16 to May 8), as well as in morphological features.
The frequency of the genotype (5 hs wh), the commonest of the genotypes in all the 5 strains, was 41 %, 72 %, 47 %, 100 % and 100 %, in
A, B, C, D and E, respectively. The frequency of spring-habit plants
increases from the northern habitat to the southern habitat, indicatingthat this type has a higher adaptability to the warmer climate. The
genotype with the combination, 5 hs wh, of "Iwate Mensury No.2"
corresponds to that of the Z-type of "Hosogara No.2". In the latter
variety, most of the population samples obtained from southern localities
belong to the Z type, and they are practically homogeneous in respect tospring habit. Thus, the results obtained from both varieties are similar
in many points, and the conclusions derived from the data obtained for"Hosogara No.2" are supported by the results of the experiment with
"Iwate Mensury No.2".
GOTOR, K. 1955-a. Jap. Jour. Genet. 30 (3): 95-106.
1955-b. Ibid. 30 (5): 197-205.
Ibid. 31. (in press).

H.

RADIATION GENETICS OF WHEAT AND BARLEY

40. Effect of X-rays on Fertility and Mutation Rate in Cereals(By S. MATSUMURA and T. FUJII)

A. Einkorn wheat
Dormant seeds of Triticum monococcum were exposed to various kindsof X-rays with different dosages or wave lengths, without a filter. The

RESEARCHES CARRIED OUT IN 1955

54

frequencies of ears with chromosome aberrations in Xl-plants and of headprogenies with gene mutations in X 2 increased with X-ray dosage (5,40013,500 r). It was also fairly certain that both the chromosome aberrations
and gene mutations increased in inverse proportion to the wave length(c.f. Ann. Rep. Nos. 3 & 5). The frequencies of both these changes
were invariably higher in var. vulgare than in var. jlavescens. Thus,
var. jlavescens shows a higher tolerance to X-rays than var. vulgare(Table 1).
There were some quantitative differences among the various kinds of
X-rays in their effect upon the single-spike fertility of Xl-plants. The
mean single-spike fertility in untreated plants was 82.67 % in var. jlavescens
and 53.32 % var. vulgare; that of X-rayed plants generally decreased indirect proportion to the increase of dosage. This relation is in goodaccord with that between the frequency of chromosome aberrations orgene mutations and X-ray dosage. Also, there is a marked difference infertility between the 80 and 180 KVP lots. The relation between the rateof induced sterility to wave length coincides roughly with the relation
between the frequency of chromosome aberrations or gene mutations towave length (Table 1). In all cases fertility was markedly lower in var.
vulgare than in var. jlavescens. The former variety matures later thanthe latter, and its fertility often becomes low and variable under the
influence of high summer temperatures. Even if this seasonal factor istaken into consideration, it is certain that the fertility of var. vulgare ismore severely affected by X-rays than that of var. jlavescens. Thismight be due to the difference in tolerance mentioned above.
Table 1. Relation between the frequency (%) of induced chromosome
aberrations or gene mutations and the fertility of spikes of Xl-plants
in Triticum monococcum,.

·---Ir-I

var. vulgare
var. flavescens
Dosage Voltage
Fertility Chromosome
Gene
Fertility: Gene(r)(KVP) Chromosome
aberration
mutation iof spike aberration mutation of. spike
in Xl
in X 2 I in Xl
in Xl. in X 2 . III Xl
1Control i
5,400 I
8,100
13,500
8,100
8,100
--.-

.. -

180
180
180
130
80

0.00
5.77
12.50
28.95
12.50
7.50

0.00
6.67
12.73
37.04
3.64
5.56

82.67
76.50
69.57
57.90
67.82
75.23

0.00
5.88
15.09
38.08
14.49
3.95

0.00
11.36
19.23
40.00
9.31
8.69

-_._----

53.22
43.28
32.67
17.70
41.47
41.06

RESEARCHES CARRIED OUT IN 1955

55

B. Two-rowed barley
Dormant seeds of several varieties of Hordeum distichum for malting
were subjected to X-ray treatment, which was applied without filter, at
180 KVP, 3 mA, 13 em, 384.5 rlmin and 8,100 & 13,500 r. There was nodifference in the germination rate between untreated and treated seeds,
but the effect of X-rays upon the fertility of Xl-plants was in proportion
to the dosage. The fertility was reduced to 68.21-99.95 % of that ofuntreated plants at 8,100 r and further to 44.02-76.27 % at 13,500 r. Various
kinds of chlorophyll mutants were also found among the seedings of theX2 generation. The frequency of head progeny with mutations was 4.22 %at 8,100 r and increased to 11.50 % at 13,500 r. This is in accord withthe relation of sterility to dosage.
41. Chromosome Aberrations in Einkorn Wheat Induced
by Irradiation(By Seiji MATSUMURA)

To examine the relation between the frequency of chromosome aberrations
and the wave length of X-rays in the PMC's of Triticum monococcum,
dormant seeds were exposed to X-rays of different wave lengths (80, 130
and 180 KVP), and different intensities (rlmin) at the same dose (8,100 r),
without filter, as recorded in the foregoing report. In the present experiment X-rays of different wave lengths at the same dosage (8,100 r)
and intensity (95 rlmin) were used with different filters; also the effectof r-radiations by CoG° was examined for comparison. The thickness ofthe filter was adjusted in inverse proportion to the wave length; that is,
at 80 KVP no filter was inserted into Matsuda's Type KXC-17 apparatus,
while at 130 KVP a filter of 0.3 Cu+0.5 AI, and at 180 KVP one of 0.8 Cu+ 1.5 Al was used. At 50 KVP and 20 KVP, irradiation was applied byanother apparatus, a Modified Type KR-75 and Type TX-20 (Grenz-rays)
without filter, respectively. The data are shown in Table 1.
At 80-180 KVP, the results recorded in the foregoing report were confirmed, but at 50 KVP the aberration frequency was unexpectedly high(c.f. Ann. Rep. No.4). This raised a question as to whether or not the
dosages were correctly measured with Matsuda's dosimeter or the "r"meter. Therefore, measurements were checked with Siemen's Universal
Dosimeter and it has become clear that the dosages at 80-180 KVP producedby the Type KXC-17 were decreased from to 8,100 r to 6,190-6,580 r,
while the dosage at 50 KVP were increased to 8,350 r.
There were marked differences between the X-rays and r-rays in theireffect upon germination rate and aberration frequency. The r-rays wereRESEARCHES CARRIED OUT IN 1955

56

more productive of abnormalities than the X-rays; at 16,200 r of r-rays,
all the seedings were uniformly small and died about one month after
germination, while with comparable X-ray treatment the disturbanceswere apparently less.
Table 1.

Relation between wave length of X- or "(·rays and frequencyof chromosome aberrations in Triticum monococcum,

DosageVoltage

(r)

(KVP)

FilterCurrent(rnA)

Control
8,100(6,190)**180!
0.8Cu+1.5Al
8,100(6,190)
0.3Cu+0.5Al
130
8,100(6,580)
80
8,100(8,350)
50-(8,100)
20"(-ray (C 0 60)
8,100
12,150
f{

3
3
4

10
10

(")

No. of I Aberrations
observedIears
No. i %
18
62

45
67*
57

44
86
62

~I--o~--l---

7
3
2
6
1
12
21

0.00
11.29
6.67
3.03
5.26
2.27
13.93
33.87

* One was haploid.
** ( ) measured by Siemen's Universal Dosimeter.

42.

"Virido-albina" Mutant in Einkorn Wheat Induced by X-rays(By Tar6 FUJII)

Chlorophyll mutants in Einkorn wheat (Triticum monococcum jlavescens)which appear spontaneously are not uncommon; such mutants may also
be easily induced by ionizing radiations. Most of them are Mendelian
recessives. MATSUMURA and FUJII (1955) found several chlorophyll mutantsof the types "albina", "chlorina", "virido-albina", "basi-viridis" and"striata ", etc., induced by X-irradiation. Some" virido-albina" mutants
appeared among the X2 -generation progeny of seeds treated with 8,100 rdose, at 180 KVP. In this mutant about 3/4 of the base of each leaf iswhite, while the rest is light green. This characteristic is already apparent in the seedling stage and the mutant invariably dies in the fieldin winter time.
When some of such mutant plants were placed in the phytotron (20°C)
and exposed to fluorescent light (about 4,000 lux), the leaves graduallybecame green, the change starting from the veins, and in about 15 days
the plant assumed the appearance of a "basi-viridis" mutant with a light-

RESEARCHES CARRIED OUT IN 1955

57

green leaf base. It required 30 more days of such treatment for the plants
to gain a normal chlorophyll content. Similar results were obtained with" basi-viridis" mutants kept in the phytotron; a significant increase ofchlorophyll content was observed. On the other hand, "albina", "chlorina"
and "striata" mutants did not gain in chlorophyll content under the same
treatment. The chlorophyll content of normal plants and several chlorophyll mutants are shown in Table 1, measured in optical density( T= -log§J of a 1/10 dilution of fresh leaves.
The "virido-albina" mutants reached the heading stage in the phytotron,
while they were lethal in the field. The time of heading and ripening inthese plants was delayed about 15 days as compared with their normal
mates, and they were significantly reduced in height, number of tillers.
and fertility. Seeds of the recovered "virido-albina" showed a relatively
high germination frequency, about 80 %. The seedlings were of course" virido-albina". When the recovered" virido-albina " plants were returnedto the field, the successive leaves showed the "virido-albina" characteristic and the mutants died in the winter.
The oxygen consumption or Table 1. Relative chlorophyll content of
respiration rate was measured byseveral chlorophyll mutants examineda Warburg respirometer. In thewith a spectrophotometer (1/10" virido-albina" mutant this rate
dilution of fresh weight)
was about half that of the normals, - - --Optical density in 4230 A
and in the recovered "viridoMutants
albina" it was somewhat higher
plants inplants infield
phytotron
than in the normals. But theactivity of cytochrome oxidase inNormal0.47
0.51
the mutants grown in the field
0.35
Chlorina
0.41
and in the phytotron was similar
Virido-albina
0.29
0.51
to that of the normals. FUJII
0.36
0.50
Basi·viridis
I(1955) has reported a similar
Basi-viridis II
0.39
0.49
tendency toward a decrease of
the chlorophyll content and theactivity of cytochrome oxidase in the "chlorina" mutant. From theseresults it has been surmised that a recovery of the chlorophyll content
without a normal activity of cytochrome oxidase can not be expected.
The relation between the increase of chlorophyll content and the activityof enzymes awaits further investigation.

58

RESEARCHES CARRIED OUT IN 1955

1.

CYTOLOGY AND GENETICS OF NICOTIANA
43.

Cytogenetic Studies on the Genus Nicotiana, VII(By YO TAKENAKA, Chao-Hwa Hu, and Katsuhisa SHIMOYAMA)The reduction divisions in PMC's were studied in 9 interspecific hybrids:
N. tabacumxN. solanifolia, N. tabacumxN. Langsdorffii, N. Debneyi
x N. tabacum, N. Debneyi x N. trigonophylla, N. sylvestris x N. tomentosa,
N. alata x N. Langsdorffii and its reciprocal, N. rustica x N. Langsdorffii
and N. longiflora x N. Langsdorffii.
(1) F 1 of N. tabacum (n=24) x N. solanifolia (n= 12)
At MI in PMC's of the F 1 of N. tabacumxN. solanifolia, from 1 to 5
chromosome pairs were found, with the mode at 1 pair. In the same
hybrid, GOODSPEED (1954) found 0-7 bivalents with the mode at 2. Accordingly, the conjugational affinity between the N. tabacum and N.
solanifolia genomes is assumed to be similiar to that in the intragenomatic
pairing within N. tabacum.
(2) F 1 of N. tabacum (n=24) xN. Langsdorffii (n=9)
In the hybrid between N. tabacum and N. Langsdorffii, which seems
to have never been investigated cytologically, the number of bivalents in
PMC's varied from 5 to 12, with the mode at 11. It is assumed thatmost of the chromosomes of N. Langsdorffii have a similarity in structure
to the corresponding chromosomes of N. tabacum.
(3) F10f N. Debneyi (n=24)xN. tabacum (n=24)
At MI of PMC's of this hybrid, 0-6 bivalents were found with themode at 2. Kostoff (1943) also observed univalents or 1-3 bivalents in the
majority of the hybrids of this combination. From these results it appears
that there is no pairing between the N. tabacum and N. Debneyi genomes,
since it is known that there is a slight degree of intragenomatic affinity
in N. tabacum.
(4) F 1 of N. Debneyi (n=24)xN. trigonoPhylla (n=12)
At MI in PMC's of this hybrid, mostly univalents, and a few-one or
two, rarely 4-5-bivalents were found. GOODSPEED (1954) also observed
mostly univalents, occasionally one or two and rarely three bivalents, inthe same hybrid. According to KOSTOFF (1943), this hybrid usually undergoes an asyndetic meiosis, with one or two bivalents, cells with morethan two bivalents being exceedingly rare. From these observations, itappears that the syndetic relationship between the N. Debneyi and N.
trigonophylla genomes is low; it is even possible that the few bivalents may

RESEARCHES CARRIED OUT IN 1955

59

have resulted from intragenomatic syndesis within the parental genomes.
(5) F 1 of N. sylvestris (n=12)xN. tomentosa (n=12)
At MI in PMC's of this hybrid, 0-7 bivalents were found with themode at 3. GOODSPEED (1954) found pairings ranging from 0 to 7 withthe mode at 3 in the same hybrid, from 0 to 7 with the mode at 2-3 in
the F 1 of N. sylvestris x N. Setchelli and F 1 of N. sylvestris x N. otophora.
KOSTOFF (1943) found in the F 1 of N. sylvestris x N. tomentosa principally
univalents, together with 1 to 4 bivalents and rarely more than 4 bivalents.
He also found in the F 1 of N. sylvestris x N. tomentosiformis even fewer
bivalents than in the former combination. T AKENAKA (1955) found 1-9
bivalents with the mode at 4 in the F 1 of N. sylvestris x N. tomentosijormis,
and also 0-5 bivalents with the mode at 2-3 in the F 1 of N. sylvestrisx N. otophora. From these results we can assume the presence of 2-4
homologous chromosomes, or large homologous sections, in the N. sylvestrisgenome and the genomes of the tomentosa group.
(6) F 1 of N. alata (n=9)xN. Langsdorffii (n=9) and its reciprocal
The meiosis of PMC's of the F 1 of N. alataxN. Langsdorffii was
generally normal, with 9 bivalents in most cases. Sometimes 7 bivalents
and one quadrivalent occurred, and also some other chromosome configurations, such as 7n+1rn+1r, 8n+2I, 6n+1rv+2I, 5n+2Iv and 6n+2m
in a few cases. In the same hybrid, AVERY (1938) found most frequently
6n+1v+1r, occasionally 7n+1rn+1r, rarely 911 and a few others, while
KOSTOFF (1943) observed most frequently 9n and sometimes 8n+2I. Our
observations essentially agree with those of the above two authors.
KOSTOFF, however, has found no polyvalent, while AVERY observed aquinquevalent in many mother cells, and rarely other polyvants; we also
occasionally found quadrivalents and rarely trivalents.
AVERY assumed that such extensive multivalency between the alata andthe Langsdorffii genomes was due to the establishment of numerous
reciprocal translocations affecting three to five or more chromosomes;
the formation of a quinquevalent in the modal class in this hybrid was
also interpreted as due to the two reciprocal translocation-an interpretation which also accounted for the distinctions in chromosome morphology in these two species. He also stated that the larger chromosomeswith a median or an approximately median centromere constituted multivalents. T AKENAKA (1955) has reported on a quadrivalent which commonlyoccurs in the meiosis of N. Langsdorffii; the two middle elements ofthis quadrivalent are large and have a median spindle-attachment while
the two terminal elements are small and have a subterminal attachment.
Two chromosomes of the quadrivalent occurring in the F 1 of N. alatax N. Langsdorffii are assumed to be derivatives of the quadrivalent found60

RESEARCHES CARRIED OUT IN 1955

in N. Langsdorffii by T AKENAKA, one large and with a median attachment
and the other small and with a subterminal attachment. The large
chromosome observed by A VERY among multivalents in the same hybrid
is probably identical with the large chromosome with a median attachment
found in N. Langsdorffii.
(7) F 1 of N. rustica (n= 24) x N. Langsdorffii (n= 9)
At MI in PMC's of this hybrid, 0-8 bivalents were found with themode at 4. Besides the bivalents and univalents, rarely polyvalents
occurred. In the same hybrid, KOSTOFF also observed 5-7 bivalents
together with some polyvalents.
In the meiosis of F 1 of N. paniculataxN. Langsdorffii, KOSTOFF (1943)
found 3-8 bivalents, and largely confirmed DREMLUG'S view (1936). In
the meiosis of F 1 of N. undulata x N. Langsdorffii studied by GOODSPEED,(1954) there were 0-4 bivalents with the mode at zero. Of the strikingly
rare chromosome pairings occurring in three hybrids between N. undulata
and three species of alata group, namely N. Langsdorffii, N. longiflora
and N. attenuata, GOODSPEED states, "Such extremely limited pairing as
occurs may be attributed to residual homologies from one postulated 6paired ancester in the PETUNIOID complex in each of the two species
concerned in each hybrid".
From the observations of many paIrIngs in the F 1 of N. paniculata
x N. Langsdorffii and of extremely rare pairings in the F 1 of N. undulata
x N. Langsdorffii the strong chromosomal affinity found in the F 1 of N.
rustica x N. Langsdorffii may be ascribed to the homological relation
between the Langsdorffii genome and the paniculata genome, which isassumed to be one within two subgenomes composing the rustica genome,
rather than that between the Langsdorffii genome and the undulata
genome which is assumed to be the other subgenome within the rustica
genome.
(8) F 1 of N. longiflora (n=lO)xN. Langsdorffii (n=9)
At MI in PMC's of this hybrid, many univalents and 2-8 bivalents
occurred, with the mode at 4, although rarely trivalents and still more
rarely quadrivalents were observed. One large chromosome was always
seen as an element of the polyvalents, resembling the large chromosome
with the median attachment of N. Langsdorffii.
KOSTOFF (1943) has found that the chromosomes in the N. Langsdorffii
genome usually conjugate with 9 chromosomes of N. longiflora, one
chromosome remaining as a univalent. Besides this type of configuration,some others, 8n+1m, 811+31,711+51, 7n+1m+21, were observed. AVERY(1938) also found in the same hybrid 6-9 bivalents, with the mode at 9.
The marked difference between our findings on the meiotic conjugation

RESEARCHES CARRIED OUT IN 1955

61of this hybrid and those of AVERY and KOSTOFF is hard to ascribe to thedifference in culture conditions or to genetic differences in the parents
used for crossing.
AVERY found one large pair among the bivalents which was composedof one large and one small chromosome held together by two chiasmata
to produce a "frying pan" bivalent. He identified the two chromosomes
concerned as a large median chromosome of N. Langsdorffiz" and one of
the short subterminal chromosomes of N. longiflora, and he showed, on
the basis of the number and position of chiasmata, that the latter chromosome is homologous in the major part of its length with one arm of theformer chromosome. In the same hybrid, he also assumed that thetrivalent, which is rather frequent, was a product of conjugation of alarge chromosome of N. Langsdorffiz" with two smaller chromosomes,
presumably of N. longiflora. T AKENAKA (1955) found a quadrivalent appearing usually at MI of N. Langsdorffii, with its two middle large
elements having median attachments and the two small terminal ones
having subterminal attachments. Accordingly, it is very difficult todetermine whether the two small chromosomes of the trivalent found in
the F 1 of N. Langsdor.ffii x N. longz"flora are two N. longz"flora chromosomes.

44.

Cytogenetic Studies on the Genus NicoUana, VIII.
A Haploz"d Plant of Nicotiana tabacum(By YO TAKENAKA and Masao TANAKA)

A variety of Nicotiana tabacum, "Bright Yellow", was pollinated with
pollen of N. alata which had been treated with X-rays (4,800r). Fromthe seeds obtained, 8,730 were sown, 150 germinated, but only two plants
reached maturity. One of them was a hybrid, and the other was a
haploid plant which was a little smaller than the parental diploid Bright
Yellow plant.
At MI in PMC's of the haploid plant, 24 univalents were most frequent,and in about 30% of the PMC's one to three bivalents were observed;
there were 0.39 bivalents per PMC on the average.
In their study on meiotic behavior in a haploid plant of N. tabacum"purpurea" conducted by CLAUSEN and MANN as early as 1924, complete
lack of pairing at MI was reported, while CHIPMAN and GOODSPEED (1927)
saw in the same material an o2casional bivalent, and interpreted it as
being due to the adherence of two chromosomes closely associated on the
MI spindle rather than a reflection of a pachytene pairing, since no association was observed at diakinesis or in earlier stages. KOSTOFF found62

RESEARCHES CARRIED OUT IN 1955

in a haplont of N. "triplex" -N. tabacum x (N. sylvestrisx N. tomentosiformis)-and in a haplont of the amphidiploid of N. sylvestrisx N. tomentosiformis, both of which he considered equivalent to a haploid N.
tabacum, chromosome associations ranging from zoro to three pairs. The
former had 0.35 and the latter 0.34 bivalents per PMC. Our observations
on the haploid tobacco reported above agree with these recorded by theprevious authors.
On the contrary, GOODSPEED (1934, 1954), in the three hybrids, otophorax N. sylvestris, N. sylvestrisx N. Setchellii, and N. sylvestrisx
N. tomentosa, found zero to seven bivalents with the mode at two to
three, while TAKENAKA (1954, 55) counted, in the hybrids N. sylvestrisx
N. tcmentosiformis, N. sylvestrisxN. tomentosa and N. sylvestrisxN.
otophora, one to nine bivalents with the mode at four, zero to seven withthe mode at three, and zero to five with the mode at two, respectively.
TAKENAKA'S observations largely agree with GOODSPEED'S findings concerning chromosome affinity between the sylvestris genome and those of
the tomentosa group.
Accordingly, the number of bivalents at MI of the hybrid between N.
sylvestris and species of the tomentosa group, is always higher than thatof a haploid tobacco. Concerning the decrease of intragenomatic affinity
in the haploid tobacco, CLAUSEN (1941) makes the assumption that, "thealterations which have diminished its duplicational completeness musthave arisen largely since it became established as an amphidiploid".
KOSTOFF (1943), on the contrary, found in the hybrid N. sylvestrisx N.
tomentosa, univalent chromosomes mostly with 1 to 4 bivalents, rarely
more than 4, and in the F 1 of N. sylvestris x N. tomentosiformis somewhat fewer bivalents than in the former cross. He stated that meiosis
of the N. "triplex" haploid and that of the haploid of amphidiploid N.
sylvestris x N. tomentosiformis could not be distinguished from the meiosis
in the F 1 of N. sylvestrix x N. tomentosiformis.
The differences among KOSTOFF'S, GOODSPEED'S, and T AKENAKA'S findings, in hybrids between N. sylvestris and the tomentosa group, may beascribed to the different methods of cultivation of their materials. Nevertheless, it is certain that the number of bivalents in the haploid tobacco
is smaller than that in the hybrids between N. sylvestris and species of
the tomentosa group.

45. Genetical Studies on the Cherry-red Leaf Color in Tobacco(By Kan-Ichi SAKAI, Sinya IYAMA and Kenjiro SAlOl
In 1954, it was found that strains within a variety differed signi-

63

RESEARCHES CARRIED OUT IN 1955

ficantly with respect to the degree to which leaf color turned cherry-red
after harvest. In the same year, we selected three strains from each of
the high and low groups with regard to the degree of cherry-redness, andselfed seeds were obtained from four to six plants in each of thesestrains. The total number of lines thus obtained was 30. Plants weregrown from the seeds and planted in the experimental plots by the complete randomized block method, with three replications. Seven leaves
from each of 15 plants per plot were collected, and after drying they
were arbitrarily assigned to five classes with scores from 0 to 4 according
to the degree of cherry-redness. The class values arbitrarily given toseven leaves of any single individual were combined by multiplication byappropriate weighting factors to construct a score, X. Then an analysis
of variance of the X's, as well as a calculation of the correlation between
years with regard to the degree of cherry-redness, was made.

1) Finding appropriate weighting jactors for classifying eachleaf with regard to cherry-redness
If we assume scores for the cherry-redness of a single leaf and asingle individual to be Xl and Xl, respectively, the score will be given by
X=aOXO+alXl+a2X2+a3X3+a4X4

where Xo, Xl> X2, .... and X4 stand for the number of leaves belonging
to the arbitrary classes, 0, 1, ... and 4. Then, for the score of a single
4

plant, Xl,

::s

4

Xk

equals seven, while for the Xl of a single leaf, 2: Xk equals
k-O

k~O

one, in which xk>O(k=O, 1, ... , 4). Weighting factors should be suchas to make the ratio of variance of Xi to that of Xl, (VXi/VXl), take themaximum value. It was found that a formula having the following
respective weighting factors would be most appropriate for the construction of the score.
X =Oxo+0.035xl +0.110x2+0.194x3+ 1.000X4

2)

Variance analysis

Results of analysis of variance of X values obtained in the manner justdescribed are presented in the following table.
Many more cherry-red leaves appeared in 1955 than in 1954. It is suggested that environmental conditions may affect their appearance, eventhough genes are certainly also responsible. Correlation between the incidence in parent and offspring was high (r=0.670, significant at the 1%
level) and it was found that strains which showed a high incidence in

64

RESEARCHES CARRIED OUT IN 1955

the previous year scored high in the next year again.
SourceBetween strains
Between lines within strains
Replication
Error

d.f.

Mean square

5
24
2
58

4.8727**0.49521.1308*0.3253**, *) Exceeds the 1% and 5% point, respectively.

J. GENETICS AND CYTOLOGY OF SOME FLOWERING
PLANTS
46. Further Investigations of Sex Chromosomes in
Rumex acetosa L.
(By Yo TAKENAKA)
Many papers have been published on polyploid and aneuploid plantsof Rumex acetosa by ONO (1930-35), YAMAMOTO (1932-38) and the present
writer (1931-41). These studies have demonstrated that the sex of thisplant is determined according to the so-called Drosophila scheme. The
following is a preliminary account of the result obtained by the writer's
further study.
(1) Frequency of triploid intersex plants found in the field.
3x~, plants with the chromosome complement 18a+2X+2Y, are rarely
found in the field. They are assumed to be the product of conjugation
between an unreduced gamete with a reduced gamete, namely, (12a+2X)+(6a+2Y) or (6a+X)+(12a+X+2Y). If the possibility of certationin fertilization between diploid and haploid pollen is taken in account,the first combination is more likely than the second.
The writer found 3328 diploid females, 1960 diploid males and 7 triploidintersexes in a field near Misima. Because of their chromosome patterns
the intersexes are grouped with males, not with females. Accordingly,
the frequency of 3x~ is 7/1967, or about 1/300. Triploid females must
be more frequent than 3x~ individuals, since it is assumed that femaleproducing pollen (6a+X) prevails over male-producing pollen (6a+2Y) on
certation in fertilization. But it is difficult to distinguish 3x-,?- from
2x-,?- in the field.
(2) Offspring of 3x!jl.
3x-,?- plants are rarely recognized in the field when we register plants

65

RESEARCHES CARRIED OUT IN 1955

based on size and fertility. The chromosome complement of 3xSf. is
18a+3X. Seeds obtained from these plants are few and show poor germination.
The sex ratio among the 40 individuals of the nature offspring of theseplants was 23Sf. : 12~ : 5~. The chromosome complements of 28 individuals observed are as follows:
Chromosome
complement
14=12a+2X
21=18a+3X
14+If**=12a+2X+ If
16=12a+2X+2Y
15=13a+2X
16=14a+2X
19=15a+2X+2Y
19=17a+2X
20=18a+2X
14=l1a+X+2Y
15=12a+X+2Y

Number of plants
9
1
1
1
3
1

1
3
1

1
6

Sex-index*
1:1
1:1
1:1
1:1
1.08:1
1.17:1
1.25:1
1.42: 1
1. 5: 1
1.83:1
2:1* Sex index is calculated according to the formula 6a: 1X= 1: 1** f-chromosome fragment

The plants examined were generally 2x and 3x, or had chromosome
numbers of approximately 2x or 3x. The sex-index was (1-1.17): 1 in
the female, (1.83-2) : 1 in the male and (1.25-1.5) : 1 in the intersex, whichis intermediate between the two.
(3) Offspring of 4x~
Among the intersexes assumed to be 3x~, one was found to be 4x~.
The chromosome complement was 24a+3X+2Y. This plant is possibly
a product of fertilization of an unreduced egg by an unreduced pollen
grain rather than being a descendant of a triploid plant. Among theoffspring of this tetraploid intersex were only females and intersexes nomale plants. Among the 1OSf. and 34~ plants, there were 34 plants
having the following chromosome complements.
Chromosome
complement
21=16a+4X+ Y
14=12a+2X
21=18a+3X
22=18a+3X+Y
23=18a+3X+2Y
19=16a+2X+ Y

Number of plants
1
2
1
3
1
1

Sex-index
0.67:1
1:1
1:1
1:1
1:1
1. 33: 1

RESEARCHES CARRIED OUT IN 1955

66

21=17a+2X+2Y
20=18a+2X
21=18a+2X+ Y
22=18a+2X+2Y
21=19a+2X
22=19a+2X+ Y
22=20a+2X

7
2

7
5
1
2
1

1.42: 1
1. 5: 1
1. 5: 1
1. 5: 1
1.58:1
1.58:1
1. 67: 1

These plants were 3x, or had chromosome numbers 1 not exactly but
approximately 3x, and only a few 2x's were found. The sex-indexesof these plants were (1.33-16.7) : 1 in the intersexes and 1: 1 or smallerin the females.

47.

Cytogenetic Studies on the Hybrid between Lilium
tigrinum and L. Maximowiczii(By YO T AKENAKA and Setsuji KATAoKA)

T AKENAKA and NAGAMATSU (1930) found 36 chromosomes in root-tip cellsof Lilium tigrinum and supposed this species to be an auto-triploid. L.
Maximowiczii, which is similar in appearance to L. tigrinum, has 24
chromosomes (MORINAGA and FUKUSHIMA 1931, NODA 1955). SATO (1936)
reported various heteroploid chromosome numbers for the F 1 of thehybrid, L. tigrinum x L. Maximowiczii. T AKENAKA (1950) demonstrated
sterility in intraspecific crosses of L. tigrinum, but hybrid fertility in
combination with L. Maximowiczii. In the same paper, he reported thevariation in chromosome number in the F 1 hybrids, and confirmed SATO'S
record.
Species belonging to the genus Lilium have polyploid chromosome setswith an apparent basic number of 12. Many other species of the family
Liliaceae also possess multiples of 12 chromosomes. It is doubtful,
however, whether 12 is really the basic chromosome number in the genus
Lilium, in view of the secondary associations found at meiosis in somespecies.
We are studying the morphology and number of chromosomes in relation to the external plant morphology of the F 1 of L. tigrinum x L.
Maximowiczii, and also the details of chromosome variation, including
chromosome pairing and secondary associations in the F 1 hybrids.
The chromosome numbers in F 1 hybrids which have been clarified up
to the present are listed below.
It is interesting that the number of individuals having 2n=28 is relatively very large. Presumably, a great majority of the egg nuclei of L.

RESEARCHES CARRIED OUT IN 1955

67

Somatic chromosome
number2425262728293031323334 35 36

25+f*28+f32+f Total

Frequency

82621113150033

1

1

47

1

* f-chromosome fragment

tigrz·num have 18 chromosomes, and the microspores of L. Maximowiczii
have 12 chromosomes. It is expected, therefore, that the chromosome
number of the F 1 plants will be mostly 30. The fact that the majority
have 2n=28, contrary to the expectation, suggests that this number represents a genetic equilibrium.

48.

The Degree of Heritability of Five Characters in Eggplant(By Kanji GOTOR)

Examination of 45 lines of F 3 and F 4 plants derived from the cross,
Kikunaga x Sendai-naga No.1, was made in a randomized block arrangement with two replications. The number of days from seeding to flowering, plant height, diameter of stem, index of fruit shape and number offruits per plant were determined on an individual basis, and the meansof 7 plants per line in each block were used for the calculation. Basedon the data of variance analysis, genetic variance and the degree ofheritability in per cent were estimated for each character.
Table 1.

Heritability in per cent.

Character

1"3

F4

Number of days from seeding to flowering

64.9

72.6

Plant height

52.0

69.6

Diameter of stem

55.0

58.3

Number of fruits per plant

34.5

48.6

Index of fruit shape

88.5

90.6

As seen in Table 1, the degree of heritability was higher in the F 4than in the F 3 generation in all comparisons, and the index of fruit shape
showed the highest degree of heritability. This was followed by the
number of days from seeding to flowering, the plant height and diameterof stem, with the number of fruits per plant presenting the lowest
heritability.

68

RESEARCHES CARRIED OUT IN 1955

For the number of days from seeding to flowering and for the index
of fruit shape, similar degrees of heritability were found by the different
estimation methods and in the different materials (GOToR, '53 and '54).
GOTOR, K. 1953. Genetica 26 (5/6):453-467.
.~, 1954. Jap. Jour. Genet. 29 (3) :89-97.

49.

Genetics of the Photoperiodic Behavior of Japanese Morning
Glory, Pharbitis Nil CHOIS., a Short-day Plant(By Sadao SAKAMOTO)

In order to study the difference in photoperiodic behavior according to
the habitat of this plant and to investigate its genetics, six strains of theJapanese morning glory-four wild strains derived from Nepal (ca. 28°N),
a strain from Tendan (Tentan) in a suburb of Peking, North China (40°N), and a strain named Violet, cultivated in Japan-were used. For
measuring the photoperiodic behavior, the position of the node on themain axis carrying the first flower bud in relation to the natural daylength in Misima (35°N) was examined. To secure a uniform external
condition, the plants were kept in a phytotron (air-controlled greenhouse)
regulated at 30°C and 80?-6 relative humidity from December 1954 toNovember 1955.
The average positions of the node in these plants under the natural
day-length in Misima are shown in Table 1.
Table 1. Variation in the average position of the node on the main axis
carrying the first flower bud under natural day-length in Misima (35°N).
No. of
I
II
III
IX
VIII
VII
V
VI
IV
experiment15i1te-of 22,Dec. 3, Feb. 22, Apr. LJunel, July 12, Aug. f, Sept.-COct. 1, Nov:s~e.<!i.I1~__ .~_ '54~55~_ ..'55
'55
'55
'55
'55
'55
'55
Nepal strains
2.3
5.3
3.1
849
2.0
18.5
00
5.0
2.8
850
2.7
4.2
5.5
3.3
00 00(21.3)* 23.5
5.7
3.0
00
852
2.4
3.6
6.0
4.9
2.2
3.0
856
2.2
2.7
3.2
3.0
19.0
1.5
2.6
Tendan
1.0
2.1
3.2
3.7
3.4
4.6
5.2
1.9
3.0
Violet
1.7
2.1
5.1
6.6
7.5 00(39.0)* 23.4
00 : did not initiate flower bud up to 20th·40th node.
*. only 3 plants of 850 initiated flower buds on the 18th, 21st and 25th node,
respectively, and only 3 plants of Violet initiated flower buds around the40th node.

RESEARCHES CARRIED OUT IN 1955

69

In December, the month with shortest day-length, all plants of all
strains initiated flower buds at lower nodes. Under longer day-lengths,
only Tendan initiated flower buds regularly, while in other strains theflower initiation was scarce; the Nepal strains particularly did not initate
flower buds on the main axis up to the 20th-40th node.
Generally, with an increase of the natural day-length, (1) the positionof the node having the first flower bud ascended, (2) the individual fluctuation of this position increased, and (3) the difference among the strains
became larger. Regarding the differences among the six strains, (1) all
the Nepal strains showed similar photoperiodic behavior and (2) the sensitivity to the dark period decreased in the order of Tendan>Violet>
Nepal.
From these results it may be inferred that the critical dark period for
the Nepal strains is longer than 9.5 hours, for the Tendan it is shorter
than 8.5 hours, and for the Violet, it is about 9.5 hours. Judging fromthe natural day-length of habitats to which the strains are adjusted, it isclear that there is a certain parallelism between their photoperiodic behavior and the day-length of their habitats.
Some plants of Nepal strain No. 850, Tendan and Violet were intercrossed and the photoperiodic behavior of the F 1 plants was examined by
the method mentioned above. All the F 1 plants showed a behavior approximately intermediate to the parents and there was no difference
between the reciprocal crosses.

50.

Polyembryony in Citrus(By Kazua FURusATa, Yasua OHTA and Kenji ISHIBASHI)

Investigations on polyembryony in Cz'trus, mainly C. Natsudaidaz', C.
sulcata and C. Unshiu, were carried out from 1952 through 1955, andyielded the following results:(1) No correlation was found between the number of seeds containedin a fruit and the mean embryo number per seed. The correlation
coefficient fluctuated irregularly between +0.84 and -0.84, from year toyear, from tree to tree, and even from branch to branch.
(2) The mean embryo number in adult plants (about 30 years old) was
higher than that in young plants (about 5 years old). This difference
was found in all species investigated, and was statistically significant inall cases.
(3) The mean embryo number varied according to the direction inwhich the fruiting branches were growing; it was higher on a north-side

RESEARCHES CARRIED OUT IN 195570

branch than on a south-side branch of a tree. This was found in allinvestigated species and the difference was statistically significant. But
there was no significant difference between the top and the base of atree.
(4) Adjacent fruits resemble each other both in seed number and in
the variation of embryo number per seed.
It is concluded that the mean embryo number per seed is considerably
influenced by the physiological condition of the tree.

51. Parthenocarpy in Citrus Natsudaidai(By Kazuo FURUSATO and Eijiro SUZUKI*)

For breeding a seedless C. Natsudaidai, it was thought important tofind out whether or not parthenocarpy occurs. For this purpose, hormone
treatment was applied.
The experiment was carried out in the flowering period by spraying
with various concentrations of phytohormone such as Naphthalene Acetic
Acid, Tomatotone, 2.4.D, 2.4.5.T, Flutone and Tomatohooks.
Only one seedless fruit was produced by the phytohormone treatment,that one with 2.4.5. T. solution (42 ppm). This fruit differed in no way insize, taste and other characters from ordinary fruits containing seeds.
This seems to show that C. Natsudaidai has a tendency to parthenocarpy.
Another experiment, namely injection of N.A.A. into young fruits,
yielded one almost seedless fruit having only small immature seeds.
However, the fruit did not grow much and had a solid texture, and it
was found unsuitable for human consumption.

52.

PolYPloid Grape Varieties(By Kazuo FURUSATO, Kenji ISHIBASHI and Yasuo OHTA)

A few cultivated grape varieties which appeared to be polyploid were
examined for their chromosome complex.
The results are as follows:
Variety
Centennial
Muscat Canon Hall
Kyoho
* Shizuoka Univ.

n

2n

38

76
76
76

RESEARCHES CARRIED OUT IN 1955

71

76
76
76
38

Kyoho bud-variant
KyohO x Kyogei
Ishihara-wase
Delaware, having gigantic fruit

Thus, Delaware, in spite of having very large fruit, was diploid, andits offspring, obtained by self-pollination, were all diploid; no triploid wasfound. This variety may be a chimera with a tetraploid epidermis.
This point will be elucidated shortly by further examination.

53. F2 Offspring of the Hybrid between Watermelon and Colocynthe(By Kazuo FURUSATO and Akira MIYAZAWA)

The hybrids (F 1) between Citrullus vulgaris (n = 11) and Citrullus
colocynthis (n=11) showed normal chromosome pairing with 1111 atmeiosis, and their seed yield was high.
The B1 from the back-cross to the F 1 , and the F 2 showed a segregationof characters as indicated in the following table.

::l~~__ ~OCynthe

CharacterB 1 and F 2

I
Colour of endocarp

pink

I
I

pink, white, ..
orange, yellow,
yellowish white,yellowish green,greenish white

white

!

.

Taste;f_~ndoc~r~ .. \_~~eet=!~b~~:=i ~?re~~-id, sweet,
Texture of endocarpl ... soft . .

II. ..

hard.. I~~:~~~:~1~te

Col~~r~f ~~~~~rp~J~ gree~ -=~a:~~g;~en~[i~~~~d dar-;-k-g-re-~-n-,Thus, the segregation proved to be very complicated.

54. Heading and Flowering of Sugar Cane(By Kazuo FURUSATO)

Some sugar canes (Co. no. 285 and C. no. unknown) were planted toobtain flowering panicles. During the first year, 1953, the plants were
kept in a phytotron, at 30°C; they were transplanted the following year,
1954, to the field. After the middle of September of that year, they

RESEARCHES CARRIED OUT IN 195572

were illuminated by artificial light for a month and half. As they did
not bloom, they were again transplanted in the late fall into a green
house. Panicles appeared in the latter part of July 1955, only on threeyear old stems.
The heading of sugar cane usually takes place in the autumn in plantations in the Northern Hemisphere. But in the above plants, the formation of flower buds apparently took place in the spring. The light periodthat induces differentiation of flower buds in sugar cane is known to be
12h 30m • It is highly probable that the differentiation of flower buds inthe above plants took place in April.

55.

Production of Triploid Sugar Beet Seeds(By Seiji MATSUMURA)

Sugar beet 2x and 4x seeds mixed in the ratio 1: 3 were sown, and"3x" seeds 1) were collected from both 2x and 4x cuttings (mother beets)("original mixed seeds"). In the combination No. 4398 (398-4x) x 162 (2x),the frequency of 3x seedlings was the highest, while the combination
No. 4398 x 399 (2x) showed the lowest frequency of 3x and the highest of
2x (Table 1). It is supposed that the predominance of 2x in the lattercase was due to the difference in the flowering period between theparental strains, because No. 399 is one of the earliest varieties and No.
4398, being an autotetraploid, belongs to the late varieties. Thus, thesynchronisation of the flowering period of the 2x and 4x plants seems to
be of great importance for the production of "3x" seeds on a large scale
by farmers. Moreover, to increase of the percentage of 3x, the numerical
Table 1.

Frequencies of 2x, 3x and 4x seedlings in three triploidcombinations, obtained from mixed seeds of
2x and 4x in the ratio of 1: 3

Combinations
4398 x 162(%)

4398x401(%)

4398 x 399
(%)

2x

3x

4x

Total

63
57
5
(50.4) (45.6) (4.0)

125
(100)

27
19
7
(50.9) (35.9) (13.2)
471
10(81.0) (17.3) (1. 7)

53
(100)

1) To be exact, mixed seeds of 2x, 3x and 4x.

58
(100)

RESEARCHES CARRIED OUT IN 1955

73

ratio of 4x to 2x seeds should be higher than 1: 3 in mixed sowing.
In the second series of experiments "3x" seeds were obtained by planting 2x and 4x beets in mixed arrangement in the ratio 1: 3. Mixed seedsof 3x-A (progeny of 4x) and 3x-B (progeny of 2x) were sown in the ratio
2:1 ("AB mixed seeds"). In the third experiment, the "3x" seeds wereobtained from mixed planting of 2x and 4x beets in the ratio 1:3 ("mixed
beet").
Comparative studies of yield and sugar content were carried out for thethree different sowings mentioned above (original mixed seed, AB mixed
seed, and mixed beet lots) in the experimental fields of the Nippon
Beet-Sugar Manufacturing Company in Hokkaido. There was no significant difference among them. But the sugar yield in these three sowingsof "3x" was rather better than that of No. 192 (2x) which is the mostwidely grown variety.

56. Karyotaxonomic studies in Poaceae, III(By Tuguo T ATEOKA)(1). Morphological convergence between Brachypodium sylvaticum andAgropyron yezoense-BrachYPodium sylvaticum closely resembles in appearance to Agropyron yezoense. In the structure of spikelet to which agreat taxonomic significance is given, the two species have a greater
resemblance than that between A. yezoense and certain other species ofAgropyron, for example, A. cil£are. The species belonging to Agropyron have large somatic chromosomes of which the basic number is 7,
and the species of the genus Brachypodium are characterized by small
chromosomes of which the basic number is not clear owing to the diversity of the numbers. Viewed from this point, the two genera must be
assumed to be phylogenically distinct. Agropyron yezoense has 2n=28
large chromosomes, while Brachypodium sylvat£cum has 2n=18 small
chromosomes. From these observations, the systematic distinction of thetwo plants is quite evident. Then, the striking resemblance of spikelet
structures between Agropyron yezoense and Brachypodium sylvaticm
should be looked upon as due to convergence which has developed in thecourse of evolution.
(2). Cytological survey of various species. The survey of chromosome
constitution of various groups in Poaceae has been continued. In 1955,
somatic chromosome numbers in the 20 species listed below were confirmed.

74

RESEARCHES CARRIED OUT IN 1955
SpeciesPhyllorachis sagittata
Bromus tectorum
Lolium rigidum
L. italicum
Briza media
Cynosurus cristatus
Festuca ciliata
Phragmites Karka
Panicum repens
Oplismenus compositus

2n
24

14
14
14
14
14
14
48
45 (5X)72

Poa nemoralis
35 (5X)
Melica ciliata
18
Asperella longe-aristata
28
Uniola latlfolia
48
Sieglingia decumbens
36
Lophatherum sinense
48
Chikusichloa aquatica
24
Setaria palmlfolia
54
S. excurrens var. pauciseta 72
Paspalum orbiculare
60

From the results thus obtained, some informations concerning thesystematic positions of the genera Phyllorachis, Uniola, LoPhatherum,
etc. were available. These cytological observations were supplemented
by the knowledge of anatomical structures of leaves, especially in thegenera Chikusichloa, Sieglingia, Uniola, etc.

K. GENETICS AND BIOCHEMISTRY OF PLNT PIGMENTS
57. Studies on Natural Anthocyanins(By K6z6 HAYASHI and Yukihide ABE)a) Crystallization of blue anthocyanz·n, and its chemical propertz"es.
Since the hypothesis that certain flower colors, especially blue colors, areconnected with the presence of metal complex salts of anthocyanins was
proposed in 1949 by K. Shibata and K. Hayashi, no extensive investigation or criticism of this problem has been published. Very recently, H.
Kikkawa and his co-workers (Science, 121 :43, 1955, and other publicationsin Japanese) have suggested that certain pigments occurring in animals,
especially the eye pigment of Drosophila, are due likewise to the formation of metal complex salts of pigment molecules. This has induced us
to undertake a renewed chemical study of blue anthocyanins. We havecarried out a series of experiments aiming at a complete purification of
the blue pigment in some plants. We have succeeded in obtaining thepigment substance found in Commelina communis in pure crystalline
form. Beautiful blue needle crystals obtained from the petals of thisweed showed several outstanding characteristics, such as: unusual stability against strong hydrochloric acid, non-permeability through a cellophane
membrane, reversion of electrophoretic behavior in contrast to that of the

RESEARCHES CARRIED OUT IN 1955

75

ordinary red form of anthocyanins, and so on. In addition, it has been
confirmed that the blue pigment crystals contain a considerable amountof metallic components, probably only Mg and K. Other metallic elements, such as Mo, Fe, Co and Ni, do not seem to take part in themolecular constitution of the crystals. These findings strongly support
our previous view that the principle of flower color variation consists notin the acidity of the cell sap but chiefly in the formation of metal-anthocyanin-complexes. Further precise studies on the chemical structure ofthis interesting substance are in progress. Thus, our metal complex
theory of color variation may provide a sound basis for the biochemical
genetics of flower colors.
b) Survey of anthocyanins in some alpine plants. An extensive investigation has been made to obtain a comprehensive knowledge of the
distribution of anthocyanin pigments in alpine plants growing in Japan.
Samples were taken from flowers and fruits of various plants found in
mountainous districts of Middle Japan. Althogether about a hundred
species from 34 families were examined by paper-chromatographic methods. Primary emphasis was laid upon the identification of the anthocyanin components, because the glycosidic combination appears to beappreciably complex, and, accordingly, its determination may be more orless tedious and difficult. Full accounts of the experimental results will
be published in the Botanical Magazine (Tokyo) shortly.

58. Genetic Control of Acylation of Anthocyanin
Pigment in Eggplant(By Yukihide ABE and Kanji GOTOR)

The anthocyanin pigments appearing in the fruit-coat, stem and flowerof eggplant were analysed by the paper-chromatographic method. It has
been shown that in general the anthocyanins found in one variety are
the same in all kinds of organs. Each of the 6 horticultural varietiesof eggplant, Burma, Sendai-naga No.1, Heta-murasaki, Shinkuro,Taiwan-naga and Emerald, possesses a characteristic acylated glycosidebeside a small amount of other constituents. Only the variety Black
Beauty has a different glycoside which is entirely free of organic acid.
The main anthocyanin spot appearing in paperchromatograms of thevariety Burma, seems to be identical with that of nasunin (p-hydroxycinnamoyldelphinidin 3-diglucoside), judging from the Rf values foundby irrigation with several solvent mixtures. However, careful examination of the products by saponification and partial hydrolysis has revealed

RESEARCHES CARRIED OUT IN 1955

76

that the main glycoside in Burma is not nasunin but its derivative, associated with an unknown substance. On the other hand, the main pigment of Black Beauty has been proved by similar tests to be delphinidin
3-glucorhamnoside.
The F 1 plant from the cross, Burma x Black Beauty, has an anthocyanin
identical with that of Burma (acylated), and the F 2 plants have anthocyanins either of the Burma type (76 individuals) or of the Black Beauty
type (non-acylated, 22 individuals), corresponding to the monogenic segregation ratio, 3: 1, (x2 =0.3401), (based on examinations of fruit-coats andstems). Thus, the acylation in anthocyanin molecule seems to be controlled by a single gene, and its effect appears both in fruit-coat andstem.

59. Further Analyt£c Studies of Flower Pigments of JapaneseMorning Glory in Relat£on to Flower Color Inheritance(By Yukihide ABE)

In Pharbitis Nil, the production of anthocyanins in the corolla is controlled by at least four complementary genes, +"a, +", +T and +a (Hagiwara, T., 1930, 1931). In order to obtain more substantial information
about this matter, some preliminary experiments were made by paperchromatography in 4 white-flower strains, 1 light yellow-flower strain,
several full-colored flower strains, and also in various F 1 hybrids between
them. These experiments have shown certain interrelationships between
the genotype and the pigment composition as shown in the following
table:
Genotypeof plant

Flower

1----

color

IG1GZ G3 G4Constituents found(;5-;1 BZ B3 YI Y--Z--'------A--n-th-o-c-y-anin+" + T +al)White+ ±+"a c + T +a White++"a +" r +a White+++**+"a +" +T a(?) White++
UnknownLight+++yellow+"a +" +T +a Colored +±(red-bluel ?
?
±
±

ca

*

G:

+ probably as leucobas

++
+*+
+

*

++

+

? I
±±

I
±

+

+
+

"
"

++

Probably flavonoid pigments B: Substances showing blue flucrescencein U.V. Y: Pale yellow substances. I) all homozygous

RESEARCHES CARRIED OUT IN 1955

77

In F 1 plants obtained from the cross between white-flower strains aswell as from white x light yellow. and white x full colored, the productionof anthocyanins is found to occur in the corolla, and the non-anthocyanin
constituents characteristic of the parent plants could be detected in small
amount in F 1 plants. On the whole, the pigment composition of F 1 plants
resembles that of the full colored flowers. Accordingly, it may be surmisedthat these non-anthocyanin constituents take part in the biosynthesis ofanthocyanin pigment in the corolla. The identification of these substances
is in progress.

60.

Separation of Natural Anthocyanins by Column Chromatography(By T6ru ENDo)

In the course of investigations of the biochemical genetics of flower
color, it became necessary to find a more simplified technique for the
separation and quantitative estimation of anthocyanin components. Consequently many partition or adsorption systems made up of various media,
organic solvents and aqueous acids, have been tested. In preliminary experiments it was shown that a mixture of anthocyanins was distinctly
separated into its pigment components by partition chromatography using
a cellulose column.
The procedure is as follows; cellulose powder (Whatman, B Quality) is
put with about ten times as much water into a glass tube (35 cm. in
length and 4 cm. in inside diameter, equipped with a glass filter at thebottom) up to the 30 cm. level, and a small volume of Hyflo Super Cel
is added together with water. For the purification of cellulose, about 50
cc. of concentrated nitric acid is run slowly from the top to the bottomof the column. After washing with about one liter of water, the column
is irrigated with about 500 cc. of the aqueous phase of the solvent mixture, n-butanol-concentrated hydrochloric-acid/water (5: 1: 4, V/V). Just
before the irrigation has been through, an aqueous solution of the anthocyanin mixture, (e.g. from Viola tricolor.) is pipetted into the top of thecolumn, and developed with about 500 cc. of the organic phase of theabove solvent mixture. By this treatment, the separation of anthocyanin
components is sufficiently good to give a well-developed chromatogram
corresponding to the Rf values in paper chromatography. On continuous
irrigation with the same solvent, the effluent solution is separated into
40 cc. portions by a fraction collector. Each fraction is subjected to apaper chromatographic test for anthocyanin components. It has thus become clear that flavonol pigments can be easily separated from the

78

RESEARCHES CARRIED OUT IN 1955

anthocyanin group, and they are usually found in the earlier fractions.
Quantitative estimation and crystallization of each anthocyanin component,
after the acid fractionation of flower extracts of Viola tricolor, are now
in progress.

L.
61.

STUDIES ON COMPETITION

Chromosome Number, Hybridity and Competitive Ability in Rice.
(By Kan-Ichi SAKAI and Hirosi UTIYAMADA)

It has been demonstrated by a series of experiments that chromosome
doubling in pure-line varieties of plants brings about a decrease of competitive ability, while an amphidiploid species is superior in competitive
ability to one or both parental species. It was also found in a barley experiment that competitive ability was independent of vigor in the growthof F 1 hybrids.
Thus, the mechanism that makes allopolyploidy advantageous and autopolyploidy disadvantageous in terms of competition still remains to be investigated. This report deals with results of an experiment comparing
the competitive ability of parents and their F 1 hybrids in rice in either
the diploid or the tetraploid condition. The species of rice, Oryze sativa
L., includes two subgroups, Indica and ]aponica, which differ from eachother in so many respects that one might even consider them different
species.
Diploid and tetraploid chromosome races of four ]aponica, and diploidraces of two Indica varieties, together with four kinds of diploid andtetraploid F 1 hybrids, were grown and tested for competitive ability inrelation to the diploid test strain, Norin No. 29, one of the most popularcommercial varieties in Japan. Plants of the test variety were grownalternately with plants of each of the races mentioned above. The experiment was conducted by the split-plot method with four replications,but the data were analyzed according to the method of randomized blocks.
Measurements were taken on the test variety, and top weight and number of panicles were recorded on an individual plant basis. Statisticalanalysis of the data thus obtained has shown that variation due either tochromosome number or to hybridity is highly significant. Mean valuesof the panicle number of the standard test variety mixplanted with 2X
and 4X races of parental varieties and their hybrids are presented below.

RESEARCHES CARRIED OUT IN 195579-- - - - - - - - - - -Top weight (gr.) of the

Sl*
S2
F1

2X

4X

38.45
36.31
28.93

42.41
39.70
36.59

S3*
K1

F1

standard test variety
mix-planted with:- ---.

*

2X

4X

35.04
27.91
17.34

41.64
34.13

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

S3
S4
F1

37.79
33.71
33.19

43.74
51. 35
46.06

Sl
K2
F1

42.15
34.47
26.68

46.06
41.63

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

Si stands for the i-th variety of Japonica subgroup, and Kj the j-th varietyof Indica subgroup.

It is to be concluded from this data that strains which allow the test
variety to have larger values are weaker competitors than those allowing
the test strain to have smaller values. It is apparent from the table thatthe 4X plants are always weak in competition with the 2X plants, bothin parental varieties and in the hybrids. It is shown further that in somecross combinations the competitive ability of the F 1 hybrids is approximately equal or inferior to that of the stronger parent, while in others it is
far superior to both parents. As a result of interaction between these
two opposed tendencies, the 4X plants of F 1 hybrids may be stronger or
weaker competitors than either parent, or they may be somewhat stronger than the weaker parent. Thus, it is quite probable that some hybrids,
very strong in the diploid condition, may be, in the tetraploid condition,stronger than the weak diploid parent, or even stronger than the strong
parent. The strong competitive ability of the F 1 hybrids is probably due
to an over-dominance effect of the genes governing competitive ability.
Sakai, K. I. and H. Utiyamada (1956) Studies on Competition in Plants.
VII. Jour. Genet. (In the press)

62. Further note on the Effect on Competition of a Varying Numberof Competing and Non-competing Individuals(By Kan-Ichi SAKAI)In Annual Report No. 5 (for 1954), I have described results of my experiments on the same problem using barley and rice varieties. This
paper is to supplement these results with some information obtained fromtwo further experiments. The plants used in the present experiments
were a variety of upland rice and the so-called red rice in one combination, and two varieties of barley in the other. The scheme of planting

RESEARCHES CARRIED OUT IN 1955

80

is identical with that in the previous experiments except that the competing plants are arranged among the six surrounding plants at random.
The analyses of variance of the data have shown that in these experiments the effect of the varying number of competing individual is always
statistically significant. Mean values of a few characters in seven kindsof treatments in the upland rice and the red rice are presented below.
Number of competing individuals among six
surrounding plants

Character
0

2
-----

Top weight (gr.)
Culm number

9.41
3.39

Top weight (gr.)
Culm number
Kernel number

7.72
4.50
169.3

3

4

5

6

5.95
2.48

5.26
2.44

4.89
2.37

-------

Upland rice
6.92
6.42
2.74
2.49
Red rice
7.55
8.65
9.05
5.16
5.11 i 4.50
178.2
170 0
208.9
1
.
7.05
2.75

I

9.45
5.27
208.6

11.92 . 13.52
6.78
6.52
304.7
266.6

The findings in these two experiments agree with those of the previous
ones, and a general conclusion which may be drawn from the past andpresent series of experiments is that the increment or decrement inquantitative characters of a plant exerted by the surrounding competitors
is directly proportional to the number of competing individuals.
Sakai, K. I. 1956. Studies on Competition in Plants VIII. Jour. Genet.
(In the press)

63. Possible Establishment of an Equilibrial State due to Competitionin Mixed Populations of Autogamous Plants(By Kan-Ichi SAKAI and Yuichiro HIRAIZUMI)This report deals with a theoretical approach to the problem of therelation between competitive ability and propagating capacity of two
genotypes in a mixed population of an autogamous plant species, eventually leading to an equilibrium. Let us assume the propagating capacitiesof the two genotypes, A and B, to be 1 and 1-s, and the competitive
abilities to be C2 and Cr, respectively. If the frequency of A and B in thet-th generation in the mixture be 1-Pt and P t , then their rates of propagation become 1-PtC2 and (l-s)+(l-Pt )cr, respectively. The frequency
of B in the t+1-th generation becomesRESEARCHES CARRIED OUT IN 1955

P

_

81

Pt{1-s+(1-Pt)Cl}

t+l- (1-Pt)(I-PtC2)+ P t{l-s+(I-Pt)c 1}

andd~t= Pt3(Cl=C2)+Pt2(C2+S-2clH.l\(Cl=~

Pt2(C2-Cl)+Pt (C 1 -C 2-S)+ 1

dt

Solving the equation, we get

t=~--log P t - I-Slog (1-P t )- {~I__ I-C2}
Cl- S

C2-S

Cl-S

C2-S

·log {(cl-c 2)Pt -(cl-s)}+log K
or

KP!_________(C2- 8 )e(Cl-8)(C2-8) t =_______(1- P t )O-8)(Cl-8){(CI-C 2)Pt -(Cl-S) }(C2- CI- C2s+CI C2)
Of the above two formulas, it is to be noticed that in the case of0, {(Cl-S)-(Cl-C2)Pt} would be more suitable. An
equilibrium between two genotypes will be reached when{(CI-C2)Pt-(C 1 -s)}<1> CI-C2 >0
C1-S

1.

Cl>S> C2
Cl <s<c2
3. Cl=S=C 2

2.

1,0

'H

o
>..

<.l

<:l

llllIl

;'<1>

<l>p.

0.6

-.-----------------------------------

1-<>"
'HoP
o
lllS::><1>.... "0....as
.....
III

~

OL---~--~:___-___:I::_--_:!:::_--_=:___-o5Time in generation
Fig.

1.

82

RESEARCHES CARRIED OUT IN 1955

Thus, among these three conditions, a stable equilibrium will be established only when Cl>S>C2' with the frequency of B, P/<J=(Cl-S)/(Cl-C2).
A graphical example, with s=0.5, Cl =0.8 and c2=0.3, is presented in Figure
1.

64.

Competition between AutotetraPloids and their DiPloid Prototypes
in Nz·cotiana tabacum L.
(By Kan-Iehi SAKAI)

An experiment comparing the competitive ability of diploid and autotetraploid races of two varieties of Nicotiana Tabacum L., White Burleyand Bright Yellow was conducted. Individual plants of the two chromosome
races of each variety were space-planted in rows, either in pure-stand plotsor alternately in mixed plots. The experiment was conducted by the complete randomized block method with three replications. Data were taken
on top weight, plant height, leaf- and flower number on an individual
plant basis, together with the flowering date. The analysis of varianceof the data obtained has shown that the difference between the twochromosome races with regard to the five characters examined wasstatistically highly significant. The effect of interaction between chromosome races and competition was also statistically significant, except for
the number of leaves and flowering date. The mean values of top
weight, plant height, and number of flowers in pure-stand and in mixed
plots of diploid and autotetraploid plants of the two varieties are presented below. P and M in the table stand for pure-stand and mixed plots,
respectively.
Bright Yellow

White Burleyzx-

2X--~-4X

4X

PMP-

M

P

M

P

M

.--_.-

Top weight (gr.)
Plant height (em)Number of flowers

452.5 701. 9 419.7 206.2
110.4 113.5 89.8 76.0
103.7 177. 9 43.3 22.1

- - - - " - - - - - - - ---------.

------

773.0 1112.7 494.4 239.0
161.9 161.8 131.0 114.1
353.7 91.4 39.4
250.0-_.----

It is apparent from the table that these three characters of the diploid
plants significantly increase when surrounded by autotetraploids insteadof diploids, while those of the tetraploids decrease by being grown in
mixture with diploid plants. It is concluded accordingly that the doublingof homologous sets of chromosomes decreases the competitive ability of
tobacco plants as has been found for rice and barley in experiments reported before.
SAKAI, K. I. 1956.
(In the press).

Studies on Competition in Plants. VI.

Cytologia Vol. 21

RESEARCHES CARRIED OUT IN 1955

65.

83

Variatz"on in Competz"tive Ahz"lity among Varieties
and Hybrid Strains of Rice
(By Hiko-Ichi OKA and Kan-Ichi SAKAI)

The experiments on competitive ability in rice so far reported suggestthat the varieties belonging to the so-called Indz'ca or "Continental"
group are superior in competition to those of the so-called Japonica or" Temperate-Insular" group. However, intervarietal variation in competitive ability has not been sufficiently investigated. In order to study
this variation among cultivated varieties of different phylogenetic groups,
and among strains derived from hybrids, experiments were conducted atTaichung, Formosa (in the second crop of 1955), with 53 varieties fromvarious Asian countries and 63 FlO strains which had been obtained bypropagating the hybrids between distant varieties in bulk or in pedigree
culture without selection. For measuring the competitive ability, Taichungno. 65, the famous "Horai" (improved Japanese) variety extensively
grown in Formosa, was used as the test strain. Fifteen test plants weregrown among about 100 plants of each variety or strain so as to be surrounded by them. The panicle number per plant of the test strain wascompared with that in single stand plots. The significance of differences
was estimated from the results of variance analysis for single standplots, distributed over the experimental field and 36 in total number.
The variation in competitive ability thus found among the varieties
and hybrid strains are set out in Table 1.
Table 1. Variation in competitive ability among cultivated varieties
and strains derived from hybrids (Increase or decrease of panicle
number due to competition with Taichung no. 65)
Group
Cultivated varieties:" Continental "" Tropical-Insular"" Temperate-Insular"
F 10 strains from:
Bulk propagation
Pedigree culture-_.--------

Weak
-3 -2

2

Strong
4 5

Num. ofvar.'s

1 2 5 11
4 2 3 1
3
2 2

10 4
1

33
12
8

2 3 9 16
1 5 11 4

1
1

40
23

-1

0

1 2

3

9
1

- - - - " , , - . _ - - _ . - - - - - - - _ .. - - - -

---

_._-

The table shows that the "Continental" (Indica) varieties generally
have high competitive ability, while the Insular (Japonica) varieties vary
in a wider range in this character. It may also be seen that among the

84

RESEARCHES CARRIED OUT IN 1555

FlO strains, those from bulk populations have higher competitive abilities

than those from pedigree culture. The same tendency has been recognized in F s strains of another cross, Pei-ku x Taichung no. 65 (unpublisheddata). This may be due to the fact that growth in bulk population encourages selection favoring higher competitive ability.

66.

Variatz"on in Competitive Ability of Rice Varieties APpearing
in Response to the Method of Growing.
(By Hiko-Ichi OKA and Kan-Ichi SAKAI)As described in the Annual Report of 1954 (p. 56), the change in the
proportion of genotypes in a mixed population of autogamous plants canbe expressed as a function of competitive ability (P) and relative propagation rate in the single stand (l-q). In order to get an example of thechange of competitive ability in response to growth conditions, a mixed
population (50:50) of two rice varieties, Taichung no. 65 (a representative" Horai " variety in Formosa) and Pei-ku (a Formosan native variety offirst-crop nature), were grown successively for three generations at Taichung, Formosa (from 1954 to 1955), under four different conditions:(1) no-fertilizer, single plant per hill, (2) no-fertilizer, 5 plants per hill,(3) no-fertilizer, single plant per hill, the period in the nursery bed being
twice as long as usual, and (4) a large quantity of fertilizer, single plant
per hill. The randomized block design with two replications was employed and the proportion of Taichung no. 65 in plant number and in seednumber (mix-harvested) were examined in each generation.
It was found that the proportion of Taichung no. 65 decreased under
all four conditions, the rate of decrease differing for each. The relative
propagation rates (l-q) under different conditions were estimated fromthe data of single stand plots. Using those (l-q) values, the value of p
in each generation was computed by the following formula (derived fromthat given in the Annual Report of 1954), in which ao and al stand forthe proportions of plant number and seed number, respectively.

p = al-aO+(aO+al- 2aOal)qao(l- ao)

The competitive ability of Taichung no. 65 compared with Pei-ku isshown in Table 1.
As the data show, the competitive ability of Taichung no. 65 decreasedin highly fertilized plots and increased when the period in the nursery
bed was prolonged. It is known, however, that in order to get bettercrops, Taichung no. 65, rather than Pei-ku, is fitted to utilize a large

85

RESEARCHES CARRIED OUT IN 1955

Tnble 1. Competith'e nbility (p) and relative propagation rate (l-q)
of Taichllng no. oS to Pei-kll under different conditions.
First cropp1-qGrowing condition•

No fertilizer, single plant, five plants, single plant,"
long nursery bed periodHigh dosage of fertilizer,
single plant

(1)
(2)
(3)
(4)

Second crop
1-q

P

0.872
0.815
0.807

-0.398-0.536-0.203

0.925
0.912
0.938

-0.122-0.129
0.038

0.949

-0.603

1.36S-0.597

quantity of fertilizer, but that often yields a poor crop when the nursery
bed period is prolonged. It is interesting to find a variety which apparently shows a higher competitive ability under conditions relatively
unfavorable to the plant.

M.

67.

GENETICS ANDCYTOLOGY OF MICROORGANISMS
AND VIRUSESElectron-microscopical Studies of Ultra-thin Sections of Penicillium
chrysogenum. II. The Fine· Structure of Mitochondria-like
Cytoplasmic Granules.
(By Seizo TSUDA)

The ultra -thin sectioning technique, developed since the invention of
the electron microscope, has made it possible to penetrate deeper into thestructure of microorganisms. Cytological studies of this kind have been
carried out by many workers, CHAMPAN and HILLIER (1953), (1956), SJOST"RAND (1954), AGAR et al. (1955), and others.
The results of the present author's investigations in fungi have previously been reported in part (1955, 1956). They show that the cytoplasm
and nucleus of these organisms have a more or less reticular structure.
The present paper offers some additional information on the fine structureof the mitochondria-like cytoplasmic granules of Penicillium chrysogenum.
The materials and the methods have been described in a previous report(1955).
The cell wall (CW) is thick and the cytoplasm shows a loose filamentous
structure; a great number of cytoplasmic mitochondria-like granules are

RESEARCHES CARRIED OUT IN 1955

86

scattered through the cytoplasm, as seen in the figures. The cytoplasmic
granules (M) are mostly spherical or oval. They are surrounded by alimiting membrane, and there is seen a system of internal ridges withineach granule.
Figure 1 shows transverse sections of mitochondria-like granules (M),each having a system of radial ridges. Notice the considerable variationin the number of the granules contained in the cells shown in Figs. 1 and2. The granules vary in size, ranging from 0.61 to 0.91/1.

CW: cell wall;

M: cytoplasmic granule.

Figure 2 shows longitudinal and transverse sections of the cytoplasmic
granules. At the left end of the micrograph is a longitudinally sectioned
granule showing a number of internal ridges. The cytoplasmic granules
are grouped in the middle of this cell.
Electron microscopical studies of ultra-thin sections inIndian Phytopathology. 8: 83-93.
TSUDA, S. 1956.
Electron microscopical studies of ultra-thin sections of
Pem'cillinm chrysogennm (II) Journal of Bacteriology. 71 (4): 450-453,
TSUDA,

S. 1955.

Aspergillns, Penicillinm and Nenrospora.

•

RESEARCHES CARRIED OUT IN 1955

68.

87

Studies on a Doubly Lysogenic Strain of Pseudomonas solanacearum(By Mitsuo TSUJITA and Chiaki MATSUI)The two lysogenic strains of Pseudomonas solanacearum, T -c 200 and
S-9, produce phages of different types but serologically related, which
may be called T -c 200 and 5-9 phages. The liberation of these phages
from bacteria occurs spontaneously, and cannot be induced by ultra-violet
irradiation.
A doubly lysogenic strain which harbors the two prophages T -c 200
and 5-9, within the same cell, is produced by superinfection of T -c 200
phage with 5-9 bacteria. From this doubly lysogenic strain a new typephage which has characters of both parents in host range specificity is
produced.
The non-lysogenic 5-10 bacteria can be artificially changed into single
lysogenic 5-10 (5-9) bacteria by infection with 5-9 phage. Before thistreatment 5-10 bacteria have no affinity for 5Pl phage (they do not adsorb
the phage). Through this treatment, however, the lysogenic 5-10 (5-9)
bacteria acquire an affinity for 5Pl phage. A similar modification of theaffinity for 5Pl virulent phage was observed in E-79 and E-3 bacterial
strains when these were lysogenized with the 5-9 phage. This phenomenon may be considered a kind of transformation due to phage infection.
By superinfection of T -c 200 phage with the singly lysogenic 5-10 (59) strain, a doubly lysogenic 5-10 (5-9, T -c 200) strain can be obtained,
and a new type phage is also produced.
The following four possible causes, may be responsible for the production of this new type phage, i) simultaneous maturation of both the parent
phages in the same lysogenic cell, ii) host induced modification, iii) spontaneous mutation, or iv) genetic recombination. Of these, genetic recombination is apparently the most plausible explanation of our experimental results. To determine the types of recombination, we have carried on analytical experiments, and found that the new type phage originatedthrough recombination in the prophage stage. This may represent a
new type of recombination.

69.

Studies on the Lysogenicity of Pseudomonas solanacearum:
Removal of Lysogenicity of the Bacterial Strain T-c 200
by Ultra-violet Irradiation.
(By M. TSUJITA and C. MATSUI)

Among various specificities characteristic of the T -c 200 of Pseudomonas

RESEARCHES CARRIED OUT IN 1955

88

solanacearum the removal of lysogenicity by irradiation with ultra-violet
light and the inactivation of free virus are the subjects of this report.
Experimental method: T -c 200 bacteria, cultured for 24 hours in potato
dextrose extract (slant), were washed in distilled water, and one ml of
the bacterial suspension was exposed to UV light (relative energy 2537A:
3129-5730A 100: 17; irradiation distance 45 cm). The irradiated suspension was diluted with potato dextrose solution and plated on agar. After
48 hours at 34°C, the number of surviving bacteria in the suspension wasdetermined by making colony counts. About 150-200 colonies among the
10 K""--====~;;:::::-"

§ 102

..,

.....

..
<>

a:l

......

llD.....I':.....>

103>..

,~: ...

----

, ";'

~

,;~/'

, ,, ,
, ,,
/

/'

" "
, , / , ,'
, ,

~,/
o

10

20

Time

Fig. 1.
A.
B.
C.

D.

30

40

50

(sec.)

Logarithmic plot of the UV survivors of T-c200 strain in
Pseudomonas solanacearum.
Lysogenic strain T-c200 as a plaque former on· SIX.
Free virus liberated from lysogenic strain T-c200.
Lysogenic strain T-c200 as a colony former. The results ofexperiments repeated four times are included in the shadedarea.
Non-lysogenic T-c200 as a colony former.

..

RESEARCHES CARRIED OUT IN 195589

300 to 500 colonies on a plate were picked at random and cultured in 3
ml of potato dextrose solution. Then the lysogenic character of eachcolony was examined by the following method.
The T -c 200 virus was spread on UV-irradiated bacterial cells of theindicator strain, and if plaques were formed, the lysogenicity of thebacterial cells was assumed to have been removed. On the other hand,in order to count the number of surviving viruses in the irradiated suspension, the non-lysogenic T -c 200 was used as an indicator strain.
Experimental results and consideration: The experimental results arepresented in Figure 1. Curve B, drawn by plotting the concentration of
the UV survivors of free virus seems to indicate that T -c 200 phages
could be inactivated by 1/2 to 1/3 hit at the initial stage of UV irradiation. This may be a kind of multiple hit curve, and may be accounted
for by assuming two types of phages present in mixture, one resistantand the other sensitive to UV. The curves D, representing the production of non-lysogenic bacteria, could not be plotted until about 20 seconds
after the beginning of UV-irradiation, because of technical difficulty. The
results of the 4 experiments are rather variable. This may be due tothe difference in the physiological condition of the bacteria at the time ofirradiation. The broken lines of D are made to fit parabolic curves.
However, if this were the case, non-lysogenic bacteria should have appeared at the start of the irradiation; the experimental results do notagree with this presumption. It is likely that non-lysogenic bacteria had
rapidly increased in an early stage of irradiation.

70.

Studies on the Multiplication of Bacterial Virus Affecting
Streptomyces gfiseus (II).
(By Seizo T~uDA)

Although fundamental problems relating to phage multiplication havebeen attacked with various genetic, biochemical and morphological methods,
important questions still remain to be solved, especially concerning geneand chromosome replication, and DNA synthesis in phage.
This investigation, carried out with the aid of an electron microscope,
is concerned with the multiplication of the bacterial virus affecting
Streptomyces griseus spores.
The material was the S-l phage strain infecting the MA-14 strain ofStreptomyces griseus, originally supplied in 1955 by Dr. H. B. Woodruff.
The spores were obtained from a 6-day slant culture on potato-glucose
agar medium.
The 5-1 phage has a uniform, tadpole shape. Its head is an ellipsoid

90

RESEARCHES CARRIED OUT IN 1955

measuring about 60 by 70 mj.t, nparly as brge as the hean of 1'2, T. andT G Escltericia coli phages; the tail is about 150 mj~ long, and about 10
mj~ wide. The head appears something like a coffee-bean and it has aninternal structure, with two elongate granules lying side by side.

The cytoplasm of the spore cell infected by phages presents a very
coarse texture, especially in the later period of multiplication of thephage. In this appearance the infected spore cell is in sharp contrast toa normal cell which shows no internal structure under observation by anelectron microscope.
Mature phages are liberated from the host spore cell, together with thecytoplasmic inclusions of the cell. The cytoplasm of the spore cell
eventually takes on a mesh-work structure when the multiplication ofphage has ceased.

N. THEORETICAL GENETICS
71. Index for Individual Selection in Autogamous Plantson the Basis of Individual Measurements, Line Meansand Line-group Means.
(By Ka'h-Ichi SAKAI)This paper deals with the theoretical construction of a selection index
for single individuals on the basis of individual measurements, the line
means and the line-group means.

RESEARCHES CARRIED OUT IN 1955

91

Let the genetic value of an individual be Y and its phenotypic value
be XI, the mean value of the line involving the individual be X2, and themean value of the group of the lines be X3' The weighting factors to
be given to Xl, X2 and X3 for constructing a selection index X are denoted
as br, b2 and b3. Then,
X=blXl+b2X2+b3X3.

Values of the three b's making the correlation between X and Y themaximum will be obtained by solving the following three simultaneous
equations:
b1V X1 +b2WXIX2+b3 WX1X3= WX1Y
b1W X1X2 +b2V X2 +b3W X2"3 = WX2Y
b1WXIX3+b2 W"2X3+b3 V X3 = W X3Y

V and W stand respectively for variance and covariance.

Variances of

Xi and covariances between Xi and Xj for the n-th hybrid population will

be given as follows:
2n - 1 -1
V X1 (F n)=

2n - 1 -1

2n- 1 D+-- 4"-1 H+E

2"-2 -12"-2 -1
E
V X2 (F,,) = W X1X2 (F,,) = --2-;~2--D+ 4"-1 H+

N

2"-3 -12"-3 -1
E
V X3 (F,,) = W X1 "3(F,,) = W X2X3 (F,,)= 2"-3 D+ --4"-I- H + NN'

where D, Hand E are components of variation (see Mather, 1949), N
and Nt stand for the number of individuals per line and the number oflines per group, respectively. Covariances between Xi and Y will begiven as follows:

2"-3-12"-3-1W X3Y (F,,)= 2"-3 D+ 4"-1 H

Thus, we are to solve the following simultaneous equations to find thevalue of the b's.
b1V X1 +b 2V x2 +b3V X3 = V x1 -E
b1VX2+b2 V x2 +b3V"3= V"2- E /Nb 1VX3+b2 V x3 +b3V X3 = V x3 -E/NN'

A few numerical examples are given for an F 4 hybrid population for

92

RESEARCHES CARRIED OUT IN 1955

any character having a heritability value of 0.1 or 0.8 in the F 2 generation. K stands for the HID ratio.
Heritability (F2)

0.1

K

Selection indexo5

X =XI + 18.6x2+ 14.5 x a
X=XI+ 5.5x2+15.1xa
X=XI+ 4.9x2+ 1. 9x ao

X=XI+ O,9X2+ 0.04x a

1

0,8

The heritability value of the selection index is given by[(b + +
lb2b a)2- (bl+_?l!2+2b~::4b 1ba - 2bl

JD

hi = = - - -2 - - - - - - - - - - - , - - - - - - - - , - - - , : : - : : - = ' - - - bI V X1 + b2(2b l + b 2)VX2 + ba(2b l + 2b'J, + ba)V xa
The correlation coefficient between X and Y is given by(

b +b + b _!!lfl~d~4ba)D+(4bl+ 2b 2 + Jia_!!1+b 2+Ea
12a
2 n- 12n+14n - 1

rXY= - - - - - .

.

--

.

)H

.. ----~~-~-~~V (VxI-E)[bI2VXI +b2(2b l +b2)VX2+ba(2bl +2b2+b3 ) Vd

SAKAI, K. 1956. Theoretical Studies in Plant Breeding Technique, III. Jap.
Jour. Breed. (In the press)

72. Formulas for Estimating the Effect of one Chromosome
on a Quantitative Character by the So-called" Reciprocal- Translocation Method"(By Hiko-Ichi OKA)

When a gene A-a is located on one of two chromosomes involved in a

1-23-4.

reciprocal translocation, 1-3 2-4' the frequencIes of the three genotypes, AA Aa and aa, among fertile and semi-sterile plants in the F 2
may be shown by the following formulas, in which p represents therecombination value between A-a and the interchange point.
Genotype
Fertile plants (F)Increment

FrequencyAAd1
2 (1- 2p+2p2)

Aa

h

-2-(

aa

-d

1

1

4p-4p2)2 (1-2p+2p2)

Mean

2p(I-2p)hRESEARCHES CARRIED OUT IN 1955
Semi-sterile plants (S)
AA
Aa
aa

d

h

93

p-p~

1-2p+2p~-d(1-2p+2p~)hp-p~

It will be found from these frequency formulas that the difference
between fertile and semi-sterile plants in mean measurement is, putting
1-2p=P,
M4S)-MF~(F)=(1-4P+4p2)h=J>2h(1)

The variance of F 2 fertile and semi-sterile plants, and the difference
between them will also be found, respectively, to be as follows:

VJi'zCF)=~ (1+J>2)d~+{(1-P4)h2+E(E:

Non-heritable component)

VF~(S)=~(1-P2)d2+~ (1-P4)h2+E
V4F)- V F2 (S)=P2d 2(2)Formula (2) can be applied for the variance of F 3 family means andthe F 2 /F3 covariance. The mean variance of F 3 families may be written
as follows:
V F3 (F) = ~-(1-J>2)d2+ ~(1-J>2)h2+E
VF3(S)=i-(1+P')d2+ ~ (l+P~)h2+E
VF/S)- VF3(F)=ip2d~+4-P'h2(3)

The above formulas, (I), (2) and (3), may hold good irrespective of theeffect of genes located on other chromosomes not involved in the translocation, and do not contain the environmental component of variance.
If we can get data by a proper design of experiment, the values of d, hand p may be estimated by using these formulas.

73.

Solution of a Process of Random Genetic Driftwith a Continuous Model(By Motoo KIMURA)

Random genetic drift is a process of change in gene frequency in a
population due to random sampling of gametes in reproduction. Since
FISHER (1922, 1930) and WRIGHT (1931) much theoretical work has been
done on this subject but the results have been largely at the level of

RESEARCHES CARRIED OUT IN 1955

94

asymptotic formulae. Recently I have obtained the complete solution ofthis process for the case of a pair of alleles using a continuous model.
Since the details have been given in the accompanying reference (1), only
the results will be presented here.
Consider a random mating population of N breeding individuals of a
diploid organism and let A and A' be a pair of alleles whose frequencies
in the population are x and I-x respectively.
In order to describe the process adequately we have to specify thefollowing three probabilities denoted by f(I,P; t), f(O,P; t) and ifJ(x,P; t)dx,
giving respectively the probabilities that A becomes fixed in the populationby the ttlt generation, that A is lost by the same generation and that thefrequency of A lies between x and x+dx(O<x<l) in the ttlt generation,
all starting from the gene frequency P at the Otlt generation:=f(I,P; t)=P+ 2.: (2i+l)pq(-I)iF(1-i, i+2, 2,p)e-[i(i+l)/4N]t,i-I

f(O,P; i)=f(l, q; t)=ifJ(x, P; t)= 2.: pqi(i+ 1)(2i+ I)F(I-i, i+2, 2, P)
i=1

xF(I-i, i+2, 2, x)e-ri(i+l)/4Njt,
where q=l-p. F in this expression represents the hypergeometricfunction which is defined by
F(I-i i+2 2 x)=I+(1-=-i)(i+2)x+C!:-i)(2-iH~+2)(i+3)x2,"
1·2
1·2·2·3+···(i=I,2,3, ... )For large t, we have the following asymptotic formula given previously (2);ifJ(x, P; t)_6pqe-(1/2.N)t+30Pq(I-2P)(1-2x)e-(3/2N)t + ...
(1) KIMURA, M. 1955. Solution of a process of random genetic drift witha continuous model. Proc. Nat. Acad. Sci., 41:144-150.
(2) KIMURA, M. 1954. Process leading to quasi-fixation of genes in natural
populations due to random fluctuation of selection intensities. Genetics, 39:
280-295.

74.

Stochastic Models for Senescence in Paramecium Based on
Random Segregation of Macronuclear Elements(By Motoo KIMURA)

It has been known to biologists for a long time that if cultures ofParamecium are kept under conditions of exclusively asexual reproduction
they lose vigor (" aging" or "senescence") and die out eventually.

RESEARCHES CARRIED OUT IN 1955

95

Recently T. M. Sonneborn has made extensive studies of this phenomenon
and conceived the hypothesis that the again is due to an accumulationof random chromosome segregations in the macronucleus. The following
is a summary of a mathematical study of stochastic models suggested tome by Dr. J. Lederberg. The macronucleus is considered to be of very
high ploidy, consisting of, say, m chromosome sets, each with n chromosomes scattered at random inside the nucleus. As the first model, we
assume that at macronuclear division each chromosome reduplicates itself,followed by the random distribution of chromosomes into two groups inequal number to form the daughter macronuclei. As the second model,
we assume that after the reduplication each chromosome has an equalchance of going to either side independently of the other chromosome.
In both models death by aging is assumed to occur whenever all chromosome of anyone type are lost from the nucleus by random segregation.
According to Sonneborn the usual strains have n~41 including strains of
n=35 and 50. Also, m is at least 100, so that mn would be of the orderof 5000. The stochastic processes involved are complicated but it ispossible to develop asymptotic theories to calculate the probability ofsurvival (Qt) after the it" generation of exclusivly asexual reproduction.
For the first model,
Qt""'(ViI:r exp [(2 log e2-1)n-((n-1)/4m)i]
and for the second model,
Qt""'(1-e- 4m/ t +4)nIn both cases Q t should be taken much smaller than unity.
For m=100, n=41, generations giving 99 % death, 99.9 % death and99.99 % death are respectively about 202,225 and 248 generations for the
first model and 175,210,246 generations for the second. These results
agree reasonably well with the finding of Sonneborn that with exclusivly
asexual reproduction many of the cultures die before 200 generations andalmost all cultures die out before 324 generations.
The models allow us to calculate the proportion of individuals showing
a recessive character due to segregation of factors in macronucleus. If
we start from heterozygotes Aa, the proportion of recessives after igenerations is

for the first model andPrr(i)_(e-2m/t +4 _e-4m/t+4)/(1_e-4m/t+4)

for the second. Numerical values of the proportion are given in theaccompanying table for several values of i(m = 100).

96

RESEARCHES CARRIED OUT IN 1955

In addition, we can calculate the allowable number of successive
macronuclear regenerations. The present models seem to suggest that,
if regeneration occurs from a random fragment of 1/33 of the macronucleus, at most only a few regenerations are possible.
t
50
100
200
300
00

75.

PI

Pu

0.197
0.316
0.389
0.500

0.024
0.127
0.273
0.341
0.500

Genic Selection in a Finite Population (Interaction between
Genic Selection and Random Genetic Drift)(By Motoo KIMURA)

Consider a randomly mating population of effective size, N, and let x
and I-x be frequencies of gene A and its allele A'. If A has a selective
advantage s over A' measured in Malthusian parameters, the probability
density ¢(x,P; t) that x lies between x and x+dx(O<x<l) at the ttl/,
generation given that x=p at t=O will satisfy the following singularpartial differential equation;
8¢
1 82
8
at =4N8x2 [x(l-x)¢]-sa;;[x(l-x)¢] , (O<x<l) ,with initial condition¢(x,P; t)=o(x-P) .

Recently this equation was used by Wright and Kerr (1954) in connection with their selection experiment in very small populations, and thestate of steady decay was successfully analysed by Wright.
I have succeeded in obtaining the complete solution in terms of theoblate spheroidal wave function studied by ]. A. Stratton and others (1941),~¢(x,P; t)= 2: Cke-'\kt+2CXVlk(Z)k-O

where c = N sand Z= 1- 2x. The spheroidal function V1k(Z) is expressed
as a series of the Gegenbauer polynomials
V1k(Z)= 2:' f~r:.(z) ,n=O,lwhere f~'s are constants and the primed summation is over even valuesof n if k is even, odd values of n if k is odd. The boundaries x=O and.1:=1 act as absorbing barriers. The details, together with further dis-RESEARCHES CARRIED OUT IN 1955

97

cussion, are given in another publication (see reference below), in which
the rate of decay due to fixation and loss of the gene has been tabulated
for various selection intensities and effective population sizes. It has
been shown that if Ns is less than about 1, there is a considerable chancefor fixation of a nonadaptive gene.
KIMURA, M. Stochastic processes and distribution of gene frequencies nnder
natural selection. Cold Spring Harbor Symposium on Quantitative Biology.
Vol. 20, (in press).

76. Rules for Testz"ng Stability of Selective Polymorphism(By Motoo KIMURA)

Recently there has been increased interest in polymorphism and many
new examples have been found in diverse organisms. This poses aninteresting problem in the theory of population genetics: What are theconditions necessary and sufficient for the maintenance of stable genetic
polymorphism by selection? I have obtained a solution subject to two
restrictions: (1) random mating, and (2) constant genotypic selective
values.
Suppose that a given locus has n alleles and let Xi be the frequency of
the it" allele, Ai. Let ali =aji) be the fitness of individuals of genotype
AiA j • The fitness may be expressed in Malthusian parameters in acontinuous model or as the selective value in the discrete case.
The necessary and sufficient conditions for the maintenance of all then alleles in stable equilibrium are: (i) the quadratic formn-l n-l

T= 2..: 2..: tijXiXj, (tij=tji)
i=1 j - I

wherebe negative definite, i.e.

tn<o, tntu >0, t n t l2 t 13 <0, etc. up to order (n-l).
t 21t 22t 2l t 22 t 23
t 3l t 32 t 33
and (ii) (-I)n-IJ i >O for all i=I,2, ... ,no Here Ji is the determinantmade by substituting one's for all the element of itl/, column in the matrix
A=[alj].

(i,j=I,···, n).

If such a stable equilibrium exists, the equilibrium frequency of the itl/,allele is given by

98

RESEARCHES CARRIED OUT IN 1955

and the mean fitness of the population becomes" J!,
a=J/2:
i-I

where J = ! A I. The result can be extended to cover the case of independent multiple loci. It is then possible to show that without dominance,
epistasis alone can not maintain a selective polymorphism. For a detailed
discussions, see the following report:
KIMURA, M.

published)

Rules for testing stability of selective polymorphism.

(to beBOOKS AND PAPERS WRITTEN BY STAFF MEMBERS

99

BOOKS AND PAPERS PUBLISHED IN 1955
BY STAFF MEMBERS
ENDO, T. 1955. Genetic studies on flower colours in pansy (in Jap.). Handbookof Biological Techniques 7 (a): 53-58. Nakayama Shoten, Tokyo.
FUJII, T. 1955. Mutations in Einkorn wheat induced by X·rays, I. Chlorina
mutants. Proc. Japan Acad. 31: 88-92.
GOTOH, K. 1955. Genetic analysis of varietal differentiation in cereals, I. Statistical differences found among local strains of a barley variety, "Hosogara No.
2". Jap. Jour. Genet. 30: 95-106.
1955. Ibid. II. Various growth habits in local strains of the barleyvariety, "Hosogara No.2". Ibid. 30: 197-205.
- - 1955. Variability of heading date in a barley variety (in Jap.). Kagaku
25: 40-41.
HAYASHI, K. and Y. ABE 1955. Studies on anthocyanins, XXV. Paperchromatographic investigation on anthocyanins occurring in the leaves of Perillavarieties. Bot. Mag. (Tokyo) 68: 71-75.
HAYASHI, K., T. NOGUCHI and Y. ABE 1955. Ibid. XXVI. tiber den Farbstoff derBliiten von Lespedeza Thunbergii. Ibid. 68: 129-133.
HAYASHI, K. and Y. ABE 1955. Ibid. XXVII. Papierchromatographishe tibersitch
der Anthocyane im Pflanazenrich (II). Farbstoffe des Herbstlaubes. Ibid. 68:
299-307.
ISHIHARA, T. 1955. A preliminary study on diurnal activity of Drosophila in
Hokkaido (in Jap.). Jap. Jour. Zoo!. 64: 90-92.
-- 1955. Some aspects on the diurnal feeding behavior of Drosophila
observed on Mt. Asahi (Hokkaido) (in Jap.). Ibid. 64: 90-92.
ISHIHARA, T. and T. H. YOSIDA 1955. Some observations on a non·transplantable
ascites tumor developing in an inbred mouse. Gann 46: 27-31.
KIMURA, M. 1955. Solution of a process of random genetic drift with a continuous model. Proc. Nat. Acad. Sci. 41: 144-150.
- ----. 1955. Random genetic drift in multi-allelic locus. Evolution 9: 419-435.
KOMAI, T., K. KISHIMOTO and Y. OZAKI 1955. Genetic study of microcephaly
based on Japanese material. Amer. Jour. Hum. Genet. 7: 51-65.
KOMAI, T. and S. EMURA 1955. A study of population genetics on the polymorphic land snail Bradybaena similaris. Evolution 9: 400-418.
MATSUMURA, S. 1955. Chromosome aberrations in Einkorn wheat induced by
X·rays. WIS (Wheat Information Service) 2: 15.
MATSUMURA, S. and T. FUJII 1955. Gene mutation in Einkorn wheat induced by
X·rays. WIS 2: 13-14.
~--- 1955. Radiation genetics in wheat. II. Relation between the mutation
effect and dose or wave length of X-rays in a diploid wheat. Seiken Ziho 7.
---.-~- 1955. Mutation in Nicotiana induced by X-rays (in Jap.). Jap. Jour.
Breed. 5: 41-46.
MATSUMURA, S. and S. SAKAMOTO 1955. Karyotypes of diploid Agropyron species.
WIS 2: 19.

100

BOOKS AND PAPERS WRITTEN BY STAFF MEMBERS

MATUURA, S., S. NAWA, M. GOTO and Y. HIRATA 1955. Studies on pteridines,
VII. "lchthyopterin", its nondentity with isoxanthopteryl-6-acetic acid. Jour.
Biochem. 42: 419-422.
NAWA, S., S. MATSUURA, M. GOTO and Y. HIRATA 1955. Remarques sur lespterines naturelles. Jour. Biochem. 42: 359-361.
NAWA, S. and T. TAIRA 1955. The eye pigment of D. melanogaster and pteridine
derivatives. DIS 29: 166-167.
OKA, H. I. 1955. Studies on tetraploid rice. V. Behavior of chromosomes in themeiosis of tetraploid rice. (in Jap.). Jap. Jour. Genet. 29: 205-214.
1955. ibid. VI. Fertility variation and segregation ratios for several
characters in tetraploid hybrids of rice, Oryza sativa L. Cytologla 20: 258266.
------- 1955. Tillering and elongation rates, culm length and other charactersin rice varieties in response to temperature. (Phylogenetic differentiation ofcultivated rice VII) (in Jap.). Jap. Jour. Breed. 4: 213-221.
- ---- 1955. Dormancy and longevity of rice seed with regard to their variations among varieties. (Ibid. X) (in Jap.). Jap. Jour. Breed. 5: 90-94.
1955. Change of gene frequency in hybrid populations of rice. (Ibid.
XI) (in Jap.) Jap. Jour. Breed. 5: 207-211.
1955. Change of gene frequency and a restriction on gene recombination in hybrid populations of rice. Jour. Agr. Assoc. China, New Series 10:
22-28.
SAKAI, K. 1955. Theoretical studies on plant breeding technique, II. Theoreticalbasis for discriminating the most desirable hybrid combinations in early
generations of hybrid bulks (in Jap.). Jap. Jour. Breed. 5: 110-114.
- - - - 1955. Secondary selection and a plan for multiplication of superior seedof rice varieties. Indian Jour. Genet. & Plant Breed. 15: 18-24.
- - - - 1955. Outlines of Plant and Animal Breeding (in Jap.). pp. 205. Asakura
Shoten, Tokyo.
SAKAI, K. and Y. SUZUKI 1955. Studies on competition in plants II. Competition
between diploid and autotetraploid plants of barley. Jour. Genet. 53: 11-20.
- - . - - 1955. Ibid. V. Competition between allopolyploid and their diploidparents. Ibid. 53: 585-590.
SAKAI, K. and K. GOTOR 1955. Ibid. IV. Competitive ability of F 1 hybrids inbarley. Jour. Hered. 46: 139-143.
TAIRA, T. and S. NAWA 1955. Yellow pigment found in the body of the mutant"sed" in D. melanogaster. DIS 29: 167.
TAKENAKA, Y. 1955. Cytogenetical studies in Nicotiana VI. On three hybrids
between N. tabacum and other species (in Jap.). Jour. Jap. Bot. 68: 358-362.
_____ 1955. Ibid. VII. Reduction divisions in the hybrids between the N.
tomentosa group and three species (in Jap.). La Kromosomo 25-26: 929-936.
.
1955. Ibid. VIII. Reduction divisions in hybrids betweenN. Sanderea
and three other species (in Jap.), Jap. Jour. Genet. 30: 236-241.
------ 1955. Cytogenetic studies in Nicotiana (in Jap.). Recent Advances in
Biology (Tokyo) 5: 152-185.

BOOKS AND PAPERS WRITTEN BY STAFF MEMBERS

101

1955. Methods of genetic experiments on plants (in Jap.). Handbookof Biological Techniques 12 (A) pp. 92. Nakayama Shoten, Tokyo.
1955. Introduction to Genetics (in Jap.). pp. 182. Hokuryu-kan, Tokyo.
TANAKA, K. 1955. Estimation of the frequency of partially sex-linked genes inman. Amer. Jour. Human Genet. 7: 163-169.
T ATEOKA, T. 1955. Karyotaxonomy in Poaceae III. Further studies of somatic
chromosomes. Cytologia 20: 293-304.
1955. Further studies on starch grains of seeds in Poaceae from theview point of systematics (in Jap.). Jour. Jap. Bot. 30: 199-208.
------ 1955. Chromosomes of Japanese grasses. A review (in Jap.). La Kromosomo 22-24: 843-879.
- ----- 1955. On the chromosomes and taxonomic placing of Beckmannia
syzigachne Fenn (in Jap.). La Kromosomo 22-24: 828-825.
TATEOKA, T. and Y. HAYASHIDA 1955. A cytotaxonomic study of Calamagrostis
arundinacea Roth. var. brachitricha Hack. (in Jap.). Jour. Jap. Bot. 30:
336-339.
TSUJITA, M. 1955. Cytoplasmic polyhedral virus infecting the silkworm. Proc.
Japan Acad. 31: 93-98.
1955. On the relation of the "lethal yellow" gene to the "lemon" in
Bombyx mori, with special reference to the maternal inheritance of lethal
yellow (in Jap.). Jap. Jour. Genet. 30: 107-117.
1955. On the crossing-over between EH and EKP of the E allelicseries in the silkworm (in Jap.). Jap. Jour. Genet. 30: 227-235.
_ 1955. Relation between lethality of H- and Kp-recombinants (E-pseudoallelic group) and enviromental conditions in silkworm (in Jap.). Jap. Jour.
Genet. 30: 252-256.
TSUJITA, M. and C. MATSUI 1955. A double lysogenic strain of Pseudomonas
solonacearum. Proc. Japan Acad. 31: 180-185.
TSUJITA, M. and B. SAKAGUCHI 1955. Genetical and biochemical studies of yellow
lethal larvae in the silkworm (1). On the nature of pterin obtained fromthe yellow lethal strain (in Jap.). Jap. Jour. Genet. 30: 83-88.
TSUDA, S. 1955. Electron microscopical studies of ultra-thin sections in Aspergillus penicillium and Neurospora. (I). Ind. Phytopath. 8: 83-93.
1955. Studies on heterocaryosis in Aspergillus and Penicillium. Ind.
Phytopath. 13: 1-8.
WATANABE, K., M. TSUJITA and B. SAKAGUCHI 1955. Studies on the mitochondrial
granules isolated from Paramecium caudatum (in Jap.). Bull. Educ. Fac.
Shizuoka Univ. 5: 153-160.
YOSIDA, T. H. 1955. Origin of V-shaped chromosomes occurring in tumor cellsof some ascites sarcomas in the rats. Proc. Japan Acad. 31: 237-242.
1955. Karyological characteristics of tumor cells. A review (in Jap.).
Jap. Jour. Cancer CIin. 1: 457-465.
1955. Genetic study on cancer, specially on cancers developed in experimental animals (in lap.). Recent Advances in Biology (Tokyo) 5: 53-87.

102

BOOKS AND PAPERS WRITTEN BY STAFF MEMBERS--~--

1955. Origin of V-shaped chromosomes occurring in Yoshida sarcoma
cells (in Jap.). Kagaku 25: 425-426.

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