NATIONAL INSTITUTE OF GENETICS(JAPAN)ANNUAL REPORT
No.3.
(1 9 5 2)•t•--00--PUBLISHED BY

THE NATIONAL INSTITUTE OF GENETICS(MISIMA, SIZUOKA.KEN, JAPAN)

.1953

I

,

NATIONAL INSTITUTE OF GENETICS (JAPAN)
ANNUAL REPORT
No.3 (1952)

Contents
Page

General statement
Abstract of diary in 1952
. . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . .. . .
Staff
,
,
, .. ..
Council'" . . .. . . . . . .
Research program for 1952..........................................
Researches carried out in 1952
, .. .. . . . . ..
A. Human genetics
1. A pedigree of hyperphalangy of thumbs and polydactyly inhands and feet.
,,,.
2, Genetics of microcephaly,.
B. Genetics of some mammals
1. Problem of the origin of tortoiseshell male cat and its sterility
2. Studies on an apparently new mutant, "alopecia periodica"
found in the mouse,.
C. Karyology of tumor cells
1. Karyological study on tumor cells of Takeda sarcome in the
rat
,
,
,
.
2. Karyological study on cells of the "quinone carcinome" inmouse.
3. Karyological study on tumor cells of the Ehrlich ascites car.
cinome in mouse
D. Silkworm genetics
1. Is there any cytoplasmic effect on unstable genes in the silkworm?
.
2. Spontaneous recurrent mutations of a modifier of the multistar
marking...................................................
3. Studies on the semi-allelic E-series in the silkworm
a. On the relation between EH and FK P • • • • • • • • • • • • • • • • • , • • • •b. On the relation between EMS and EMc.. .. .. .. .. .. .. .. .. ....
4. Maternal inheritance of "Lethal yellow".. . . . . .. . . . . . . . . . . . .
5. Genetical and biochemical studies of yellow lethal larvae ....
6. A trisomic silkworm produced by treatment with BRC powder
7. Genetical and biochemical studies in the Eri-silkworm........

1
2
3
4
5
8

8
8
9
9

10
12
15

17
19
20
20
22
24
27
28
32

E.

Cytology of some insects
1. Cytological study on racial hybrids of Philosamia cynthia(Lepidoptera, Saturnidae)
2. Multiple sex-chromosome mechanism in Rhaphidopalpa
femoralis (Coleoptera, Chrysomelidae) .... .. .. .. .. .. .. .. .. ..
F. Population genetics of some butterflies and a land-snail, .. .. ..
1. The butterflies Colias and Neozephyrus
2. The land-snail Bradybaena, .. . . . . . . .. . . . . . . . . . . . .

G. Genetics of some cereals
1. Irradiation experiments with X-rays in einkorn wheat.. ..
2. Effect of ultra-short-wave irradiation on einkorn wheat
3. Cytogenetic studies of wheats and their relatives
H. Genetics and cytology of Nicotiana
1. Cytogenetical problems in the genus Nicotiana
2. Irradiation experiments with X-rays in Nicotiana.. . . . . . .
3. Cytogenetic studies on the genus Nicotiana IV
a. Reduction divisions in hybrids between N. glauca and theN. alata group .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
b. Reduction divisions in hybrids between N. tabacum and threeother species"," ., . . . . .. ..
c. Reduction divisions in hybrids between N. suaveolens andthree other species .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .
4. Genetical studies on the mid-rib proportion and the leaf-shape
in tobacco plants
I. Genetics of Solanum and Capsicum
1. Genetic studies on eggplant (Solanum melongena L.)
a. Regression analysis of quantitative gene action .. . . . . . . . . . .
b. The heritability of some quantitative characters and estimation of the minimum number of genes
2. Inheritance of fruit color in Capsicum
3. On genes controlling quantitative characters in Capsicum
annum LJ. Genetics of some flowering plants
1. Cytogenetic studies on sex in Cannabis sativa II. Meiosis in
diploid, triploid and tetraploid males........................
2. Pigment constitution of Viola tricolor........................
K. Improvement of some useful plants
1. Improvement of sugar beets by means of induced triploidy ..
2. Tetraploidy in Citrus........................................
3. Abnormal growth of Citrus trees caused by deviating chromosome numbers in the grafting stocks
4. Prospects of using triploids in tabacco breeding .. ", ., .. ..

ii

34
35
36
36
36
37
38

t

38
39
40
40
41
42
42

44
45
46
47

48
49
50

51
52
53

,

,

L. Genetics of moulds
1. Appearance of reversional mutants in the methionine-requiring
strain of llstilago r.naydis
2. Studies on heterocaryosis in Aspergillus and Penicilliur.n, ..
M. Studies on competition
1. Competition between diploid and autotetraploid plants ofbarley,, ., .. .. ..
.. .. ..
2. Competition between an artificially synthesized amphidiploidand its ancestral species of Abelr.noschus . . . . . . . . . . . . . . . . . . . .
3. Intervarietal difference incompetitive ability in Hordeur.nsativum L. and Oryza sativa L.
4. Competition between the upland-rice plant and the "red-rice"plant,, .. .. .. .. .. .. .. .. ..
N. Theoretical genetics
1. Theoretical considerations on random drift of allelic genes or
chromosomes and decrease of heterotic vigor in allogamousplants,,, .. .. .. .. .. .. ..
2. "Stepping-stone" model of population
3. Process leading to quasi-fixation of alleles due to random
fluctuation of selective values
4. On simultaneous distribution of gene frequencies in populations

"

iii

54
55

56
57
58
59

60
62
63
65

,

GENERAL STATEMENT
During the current year, the Institute acquired considerable additions to its equipment and improvement of its property. A new
two-storey concrete building, 180.520-tubo (1 tsubo=6 ft. square) infloor dimentions, was completed to house the following; a library, areading room, a librarian's office, two chemical laboratories, andan optical laboratory on the first floor, and on the ground floor anelectron-microscope room and an X-ray apparatus room each witha vestibule, four constant temperature rooms for culture of Drosophila and silkworms, a set of constant temperature rooms regulated at - 5",,0, 0",,5, 5",,10, 15",,20, 20.......25, 25",,30°0, respectively,
and a room for a super-sonic wave apparatus and an ultra-shortwave apparatus. Another new 26.46-tubo building is a plantron
which is the first to be constructed in this country. Also, a large
46-tubo glass house was constructed primarily for research on
tobacco plants. These increased facilities are giving great impetus
to our research work.
The library has been expanded by acquisition of current numbersof periodicals and new reprints. Especially, Dr. GOLDSCHMIDT hascontinued to send his reprints and journals which help to keep thelibrary up to date.
T. Ito resigned and his place was filled by T. IlNo. T. H. YOSIDA
was transferred from the Faculty of Science of Hokkaido University
to the Institute. Dr. Flora Alice LILIENFELD, who had been connected with the Japan Monopoly Corporation, concurrently became a
research associate of the Institute. M. TSUJITA was awarded the
Sericological Prize for his study on cell inclusions, especially mitochondria, of the silkworm.
The following research grants were received during the current
year by our staff. These grants have been of great aid to our
research projects.
From the Scientific Research Fund of the Ministry of Education:
to K. OGUMA and coworkers (including T. KOMAI and K. TUTIKAWA),
for: Breeding and preservation of strains of rats and mice usefulfor medical research purposes,- Y800,000.
1T. KOMAI and coworkers (including K. SAKAI and M. KIMURA),
for: Researches in population genetics,- ¥510,000.
Y. TANAKA and coworkers (including M. TSUJITA), for: Fundamental and applied genetics of the silkworm,- ¥350,000.
T. KOMAI and coworkers, for: Genetic and psychological studies
on human microcephaly,- ¥ 50,000.
From the Scientific Experiment Fund of the Ministry of Education: to S. MATSUMURA and coworkers, for: Breeding of triploidsugar-beet strains,- ¥100,000.
M. TSUJITA, for: Researches on genetics and selection of abnormal eggs of silkworm,-¥ 50, 000.
The Institute was provided by the Ministry of Education withan extra-budgetary fund amounting to ¥7,080,000 for the construction of the plantron.
Among a number of visitors were Dr. K. RAMIAH of FAO of UN.,
Prof. H. H. PLOUGH of the AEC in Washington, D.C. and Dr. D.J.
McDONALD of ABCC, Hirosima.

ABSTRACT OF DIARY IN 1952
February 9. Tenth meeting of Misima Geneticists' Club.
February 21. Sixth meeting of the Board of Councillors.
March 29. Eleventh meeting of Misima Geneticists' Club.
April 25. Joint meeting of the National Committee of Genetic
Researches and the National Committee of Researches in Animal
and Plant Breeding of Japan Science Council. Committee meeting of the Genetics Society of Japan.
May 31. Twelfth meeting of Misima Geneticists' Club.
June 26. Board meeting of Association for the Propagation of theKnowledge of Genetics.
July 22 to 29. Summer course in biology for teachers in local
high schools.
August 4. Seventh meeting of the Board of Councillors.
August 23. Report on the trip to Pakistan and Mghanistan by Mr.
O. SUZUKA.
October 25. Phage Symposium.
November 8. Thirteenth meeting of Misima Geneticists' Club.
2{

November 21. Meeting of directors of research institutes under
the jurisdiction of the Ministry of Education.
December 19. Meeting for interim reports on fundamental studies
for the improvement of tobacco plants.
STAFF~

Department and Laboratory Heads
Kan OGUMA, D. Agr., Director, and Head of the Second Department
Yoshimaro TANAKA, D. Agr., D. Sc., Head of the First Department
Taku KOMAI, D. Sc., Head of the Third Department
Part-time Staff
Hitoshi KIHARA, D. Sc., Professor of Kyoto University
Yosito SINOTO, D. Sc., Professor of Tokyo University
Laboratory Heads
YO TAKENAKA, D. Sc.
Kan-ichi SAKAI, D. Agr.
Seiji MATSUMURA, D. Agr.
Mitsuo TSUJITA, D. Agr.
Kazuo FURUSATO
Research Associates
Yoshinari KuwADA, D. Sc.
Flora Alice LILIENFELD, Ph. D.
Junior Investigators
Tosihide H. YOSIDAMoM KIMURA
Kanji GOTOH
Akira MIYAZAWA
Bungo SAKAGUCHI
Toru ENDO
Kiyoshi TUTIKAWA
Tetuo llNO
Seizo TSUDA
Assistants-10
Department of Administration
Morihei Tsukamoto, Head of Department3

Sumiyoshi SUGIO, Head of General Business Section
Masao MIYAZAWA, Head of Finance Section
Naomi MATSUBARA
Hiroko NAKANO
Junzo KADOWAKI
Clerks, Typist, Telephone operators, Chauffeurs, Field laborers,
Janitors, etc.-14.

Misima Branch of Hatano Tobacco Experiment Station
Masao TANAKA, Head
Flora Alice LILIENFELD
Seiji IMAI
Assistants-3.
Whole-Japan Association of Poultry Genetics
Kan OGUMA, President
Yoshimaro TANAKA, Vice-President and Director of Researches
Take NAKAMURA, Managing Director
Association for Propagation of the Knowledge of Genetics
Kan OGUMA, President
Y6 TAKENAKA, Managing Director
Seiji MATSUMURA, Managing Director
COUNCIL
Yo K. OKADA, Professor of Tokyo University, Chairman
Seishi KAYA, Professor of Tokyo University, Vice-Chairman
Konosuke AKIYAMA. President of Japan Monopoly Corporation
Eikichi HIRATSUKA, Director of Agricultural Technique ResearchInstitute
Seizo KATSUNUMA, President of Nagoya University
Makita KOGURE, Professor of the Tokyo College of Agriculture
and Technology
Yoshio KOYA, Director of the Institute of Public Health
Kiyoshi MASUI, Professor of Nagoya University
Bungo MIYAZAWA, President of Women's College of Anjo University
Toshitaro MORINAGA, Head of the Department of Physiology andGenetics of Agricultural Technique Institute
4

.'

•

Waro NAKAHARA, Director of Cancer Research Institute
Masanori NAKAIZUMI, Professor of Tokyo University
Yusuke SUMIKI, Professor of Tokyo University
Yfishi UCHIMURA, Professor of Tokyo University
Yasuke YAMAGUTI, Professor of Ibaraki University
RESEARCH PROGRAM FOR 1952

Tanaka Laboratory
Unstable genes in silkworm-TANAKA
Genetics of dominant "retarded" strain of silkworm-TANAKA
Genetics of recessive "retarded" strain of silkworm-TANAKA
Photoperiodic effect on the diapause of the wild silkworm Antheraea
pernyi, and the genetics of diapause-TANAKA
Lethal genes in the silkworm-TANAKA
Hereditary malformations in the silkworm-TANAKA
Linkage of "small egg" strains-TANAKA
Breeding and preservation of pure strains of rats and mice for
medical purposes-OGUMA and TUTIKAWA
Genetics of the differences among strains of mice in respect to susceptibility to tumors-TUTIKAWA
Lethal genes in rats and mice-TUTIKAWA
Matsumura Laboratory
Radio-genetic studies on wheat-MATSUMURA and FUJIIGenom in Agropyrum, a close relative of Triticum-MATSUMURA
Nullisomic plants found among the progeny of pentaploid hybrid
wheat-MATSUMURA
Breeding of a strain of wheat resistant to rust-MATSUMURA andHIRATSUKA (Tokyo Univ. of Education)
Breeding of a triploid sugar beet-MATSUMURA et al.
Origin of the plants of the genus Lycoris and their distributionKIHARA and LILIENFELD
Genetic studies on the variations induced by ultra-short waves andsuper-sonic waves-MATsUMURA and FUJII
Mutation in Nicotiana induced by X-ray irradiation-MATsuMURA,KIHARA and FUJII
Furusato Laboratory
Breeding of varieties of Citrus-FuRUSATO and MIYAZAWA
5

Biochemical genetics on flower colors-ENDo and MIYAZAWA
Polyploidy and grafting-FuRuSATO
Sterility in cultivated plants-MIYAZAWA
Biochemical studies on plant pigments-ENDO
Ogurna Laboratory
Origin of sex-chromosomes-OGUMA
Phylogeny of plants based on karyotypes-TAKENAKA and SINOTO
Genetics of right- and left-handedness in plant organs-KIMuRA and
KIHARA
Theoretical studies on problems of population genetics-KIMURA
Theoretical studies on gene action-KIMuRA
Experimental studies on polygene system-KIMuRA
Theoretical studies on crossing over-KIMURA
Takenaka Laboratory
Origin of differentiation of sex in higher plants-TAKENAKA
Collection and preservation of varieties of useful plants-TAKENAKA
Cytogenetics of some fungi-TAKENAKA and SINOTO
Karyological studies on natural polyploidy-TAKENAKA
Karyological studies on polyploids of cultivated plants-TAKENAKA
Cytogenetic studies on interspecific hybrids in Nicotiana - TAKENAKA
and SUSUKI
Heterokaryon in Aspergillus-TsUDA

Kornai Laboratory
Genetics of human microcephaly-KoMAI, KISHIMOTO (Nagoya Univ.)
and OZAKI (Inst. Publ. Heath)
Population genetics of the lady beetle, Harrnonia-KoMAI
Population genetics of the land snail, Bradybaena-KoMAI
Theoretical and experimental studies on genes-KoMAI
Experimental studies on the mechanism of aberrant mitoses-YoslDA
Experimental studies on the cytology and biochemistry of tumorsYOSIDA
Studies on culture of normal and tumorous tissues - YOSIDA
Sakai Laboratory
Genetics of fruit crops-SAKAI, GOTOH and SUZUKI
Competition between individual plants of different genetic constitution - SAKAI and SUZUKI
Theoretical and experimental studies on selection in plant breeding6.'

SAKAI
Genetics of quantitative characters in tobacco plants-SAKAI, GOTOR
and IYAMA
Genetic studies on flowering plants - GO'fOR
Tsujita Laboratory
Lethal eggs and sterility in silkworm-TSUJITA and SAKAGUCHI
Virus infecting silk-producing insects-TSUJITA and SAKAGUCHI
Manifestation of gene effects-TsuJITA and SAKAGUCHI
Developmental genetics of the silkworm-TSuJITA and SAKAGUCHIMinute structures of chromosomes-TsuJITA and SAKAGUCHI
Cytogenetics of silkworms, especially polyploids-TsUJITA andSAKAGUCHI
Mitochondria in insect cells-TsuJITA and SAKAGUCHI
Research Students and Research Subjects
Toshihiko OKUBO: Genetics of silkworm and poultry
Tosiaki SUZUKI: Induced mutation
Kyozo WATANABE: Genetics of protozoa
Yasuo SUZUKI: Population genetics in cultivated plants
Etuo GOT a: Microtechnics
Seiji TEZUKA: Silkworm genetics
Hirosi EBIHARA: Breeding of tobacco plants
Sinya IYAMA: Breeding of tobacco plants

7

RESEARCHES CARRIED OUT IN 1952

A.

HUMAN GENETICS(Report by Taku KOMAl)

1.

A Pedigree of Hyperphalangy in Thumbs and Polydactyly
in Hands and Feet

A kindred having an abnormality of the hands and feet has been discovered near Sibukawa, Gumma-ken. All the affected individuals have threejointed thumbs, and some of them also bear extra thumbs and bifurcatedbig-toes. This abnormality seems to have originated as a new mutant ina woman who was the mother of the present generation, and has appearedin t~m of her descendants. The trait is inherited as a simple dominantwith nearly perfect penetrance, but varying in expressivity and specificity
to some extent.
2.

Genetics of Microcephaly

The writer has continued, with the cooperation of Prof. K. Kishimotoof Nagoya University and Dr. Y. Ozaki of the Institute of Public Health,
his study on human microcephaly. So far, 119 cases belonging to 61 sibships
have been accumulated. A recessive gene is apparently responsible forthe great majority of these cases. Eight sibships contain more abnormals
than could be expected on the postulate of a recessive gene with probability
lower than 0.05, suggesting that some other genetic or non-genetic cause
is at work. Excluding these cases, the incidence of the recessive genefor microcephaly in the population has been estimated by means of
Dahlberg's formula:c (l-k)q = --=-=~--':-:=---'--o16k-15c-ck,
where q denotes the incidence, k the rate of cousin marriages among theparents of the affected individuals and c the rate of cousin marriages in
the whole population. In our material k is 0.54, while for c, the value
0.06 found previously by the ABCC group was used, giving the value
0.0036 for q. This value comes very close to the values found by otherauthors for the genes for some rare abnormalities in man, such as albinism,
amaurotic idiocy, congenital total color-blindness and ichthyosis congenita.
Based on this value of q, the rate of mutation of the recessive gene formicrocephaly was computed by means of the formula:8,m=(l- f)[aq+(1-a)q2],
where m stands for the mutation rate, f the fertility of the abnormal
individuals in comparison with that of normal individuals, and a for thecoefficient of inbreeding in Wright's sense. By using 0.05 for f, and
0.005 for a, the value 3.0 x 10- 5 has been found for m. This value of mcomes close to the known values for the mutation rates of the genes
responsible for certain rare congenital abnormalities in man, such as
hemophilia, albinism, retinoblastoma, etc.

'.

B.
1.

GENETICS OF SOME MAMMALS

Problem of the Origin of the Tortoiseshell Male Cat
and its Sterility(Report by Taku KOMAI).

Records of tortoiseshell males with statements of coat colors of theirparents and litter mates have been collected. This is to test the validityof the writer's new hypothesis on the origin of this kind of males presented
in No. 2 of the Annual Report of the Institute. A popular article by thewriter on this subject on the Yomiuri Newspaper was highly contributive
to this attempt. Thus the writer has been able to obtain to date records
of as many as fifty cilts whose identity as tortoiseshell males seems certain.
Many of these specimens were examined by the writer, or by other biologists provided with a sufficient knowledge of the diagnosis of this kind ofcat. The rest have been judged as fairly authentic by color sketches
prepared by the owners of the cats. Since there is hardly any way ofgetting cytological proof either for or against the hypothesis, the writer
has to seek indirect evidence in the data of coat colors of parents a~dlitter mates of such a male. A fairly convincing proof against the hypothesis
might be obtained if it is found that more than one tortoiseshell male wereborn of the same mother. So far, all the reports of such occurrence havebeen found to be false, due to the wrong diagnosis of the coat color.
Moreover, all the available reports on coat colors of parents and litter
mates, except for a few doubtful ones, conform with this hypothesis.

2.

Studies on an Apparently New Mutant, "Alopecia
Periodica" found in the Mouse(Report by Kiyosi TUTIKAWA)"Alopecia periodica", (ap) is a recessive spontaneous mutant whichappeared in 1951, in a sib-mated stock of Mus musculus maintained in our
Institute. In the homozygous condition, ap produces several lesions in9the integument which are at first sight apparently unrelated to each other.
The homozygous young of this strain may already be distinguished fromthe normal sibs at birth, and more easily on the 3rd--4th days by theshorter whiskers and also by the fact that the first coat is very short andsparse. At the age of from 13 to 15 days, the abnormal young start
shedding their coat hair. The shedding is usually complete in 20-24 days
except for some regions, around the nose, toes, and tail which have a
few hairs left. Mter the loss of this first coat, the skin remains soft,
smooth, and of a pinkish colour, until the next coat begins to grow.
Then a peculiar type of hair regeneration sets in, with a gradient in anantero-posterior direction. While the coat in the posterior region of the
body is stilI incomplete, a gradual thinning recurs in the anterior region.
Thus, the loss and regeneration of hair is repeated with about ten-day
intervals throughout life, although the loss and regeneration of the hair inlater generations does not recur so regularly as in the earlier stages, andthe same individual may show regions belonging to two or even threesubsequent hair generations simultaneously.
During the first coat growth, the skin appears dry and scaly. In somesevere cases the scales form rigid plates all over the body, and the animal's
life is endangered. The scaly skin often forms a number of rings on thetail, and the distal part of the tail may become necrotic.
The developing coat of the ap mouse in all hair generations apparently
consists of guard hairs, awls, auchenes, and zig-zags which are, however,histologically abnormal. Mter the second or more generations of the haircycle, especially the black fur becomes modified into silver-coloured. This
modification of the black tone may be under the control of a modifying
gene. The vibrissae of the adult ap mouse are short. The eyelids may
be thickened, possibly due at least in part to shortening and reductionin the number of eyelashes. The teeth and nails are not affected. Bothsexes of ap are fully fertile, but in females the ability to suckle their
young is sub-normal.

C.

KARYOLOGY OF TUMOR CELLS(Report by Tosihide H. YOSIDA)

1.

Karyological Study on the Tumor Cells of Takeda
Sarcome in the Rat

Karyological studies on ascites tumor in rats have been carried out by
MAKINO, YOSIDA, KANO and TANAKA (1948-1953). Makino has found in
Yoshida sarcome the presence of strain cells which are characterized byhaving about 40 chromosomes, including large V-, small V- and small Jshaped elements.
10

The Takeda sarcome used in the present study is transplantable ascites
tumor found in the rat (TAKEDA 1952). This paper deals with my cytological observations on the tumor developed in one animal.
(1). Frequency of tetraploid cells: This rat died of the tumor on theseventh day after transplantation. 127 metaphase plates of the tumor cells
were observed through the life span of this animal. 106 (83.4%) among
them were tetraploid, 14 (11.0%) were diploid, and the remaining 7 cells(5.5%) were hyperploid. It is evident from this observation that most of
the cells constituting this tumor are tetraploid and they form the strain
cells of this tumor;
In order to see whether these tetraploid cells normally multiply withregular mitoses or not, the relative frequency of cells of the ordinary
division type, the aberrant type and the disintegration type (d. MAKINO &YOSIDA 1951) were examined throughout the life span of the tumor animal.
Table 1.

Frequency of the tetraploid cells occurring in Takeda sarcome.
Diploid (±2~~-Tetraploid(±_41lL __Frequency%
Table 2.

Hyperploid(>±4n)

106

14

7

83.4

11.0

5.5

I

Total
127
99.9

I

Frequency of the cells of different types occurring in tumor cells.
---_.-----

Types

Division type

Aberrant type-_.-----------

Disintegration
type

Total

Frequency

57

20

29

106

%

53.7

18.6

27.3

99.6

Table 3.

Chromosome numbers of tumor cells in Takeda sarcome.

No. of chromo
104
89
86
85
84
83
82
80
76

No. of obs.

No. of chromo

No. of obs.

1
2
1
1
4
1
1
2
1

73
69
48
43
40
38
37
36
Total

1
1
1
1
2
3
1
2
26

1I

I

I
I
I

11

As seen in the table, the frequency of cells of the division type, aberrant
type and disintegration type was 53.7, 18.6 and 27.3 per cent respectively.
It has been considered by the authors (MAKINO & YOSIDA 1951) that thecells of the division type multiply by active mitoses in the peritoneal cavityof the host. The above observations show that many tetraploid cells in
the Takeda sarcome actively multiply by regular mitosis.

Figs. 1-2. Chromosomes of the tumor cells in the Takeda sarcome.
1 and 2, showing 86 and 82 chromosomes respectively. J = large J -shaped chromosomes, V = large V -shaped chromosomes.

(2). Chromosome numbers in the tumor cells: Of importance is the number of chromosomes of these tumor cells. The results of my observations
are tabulated in Table 3. The chromosomes were counted on sketches ofgood metaphase figures. The cells having ca. 84 chromosomes were mostcommonly represented. From the above data, it can be concluded thatthe strain cells of the Takeda sarcome are characterized by having ca. 84
chromosomes.
(3). Karyotype of strain cells: The karyotype of strain cells has been
analyzed from seven metaphase plates containing 76, 80, 82, 83, 84, 84 and86 chromosomes, respectively. In five of these cells there is a conspicuous
I-shaped element besides the large or small V-shaped elements which are
regularly found in Yoshida sarcome cells.
Thus, the strain cells of the Takeda sarcome not only show a marked
difference in karyotype from the normal somatic cells, but also from thecells in other tumors such as Yoshida, MTK or Hirosaki sarcomes.

2. Karyological Study on Cells of the "Quinone Carcinome" in Mouse
The "quinone carcinome" is a carcinome which was induced in themouse epidermis by Prof. TAKIZAWA (1946) of Chiba University, by paint12

ing benzol solution of p-quinone on the skin. Observations carried out by
the author on the chromosomes in the cells of this tumor have revealed
the following facts:( 1). Frequency of polyploid cells: The data on the frequencies of
diploid, tetraploid and hyperploid cells occurring in the tumor tissue aresummarized in Table 1. It is noticeable that the tetraploid cells occur
with a frequency as high as 77 per cent. These tetraploid cells multiply
by normal mitoses. The diploid cells, which occur with a frequency of
about 5 per cent, often show abnormal mitotic behavior. From the above
Table 1.

Frequency of tetraploid cells occurring in the quinone carcinome.

~Diploid (±2n) I Tetraploid (±4n) I Hyperploid (> ±4n) I

Total

Frequency

4

60

14

78

%

5

77

18

100

Table 2.

Chromosome numbers and karyotypes of the tumor cells.
~-------_._._-----

Karyotypes
No. of chromo
Rod
80
80
79
79
78
77

76
76
76
76
75
75
75
75
74
69
68
48
34

77
79
71
75
72
70
71
69
72
68
70
61
67
74
67
65
59
46
32

Small V
2

I Medium vi Large V
I

4
2
4

1
1
1
1
1

2

2

2

2

1
2
1
6
3
10
1

1
2

Trabant

1
1
1
1
1

2

Dot

2

1

3
2

1
1
1
3
1
1

1
1
2
2

1

1

13

2
1

2
5

1
1
2

1
3

1

2

1

data, it can be surmised that the tetraploid ceIls are the strain ceIls of
the quinone carcinome.
(2 ). Chromosome numbers of the tumor ceIls: The chromosome numbers determined on good metaphase figures are presented in Table 2.
The number shows a wide range of variation from 34 to 80, ceIls having
about 75 chromosomes being most frequent.
( 3 ). Karyotype analysis of the tumor celIs: In the germ ceIls of themouse, MAKINO (1941) has observed 40 chromosomes, all of a simple rodshaped type. The author has confirmed the correctness of this finding by
the squash technique. A comparison of the chromosomes in germ ceIls
with those in tumor celIs discloses a marked difference, especiaIly withrespect to the chromosome number, and in the occurrence of V-shaped
elements in the latter. The V-shaped elements which are usually foundin the tumor cells can be classified into three types; large, medium and,,,n~'J'~' ,fa ...
..",~.

,-- . ...

:-l· , .I''.'~
-:."

.-~
"'~
~~~

wl~'·\t2

MV
Fig. 1. Chromosome of the spermatogonial metaphase in the mouse;
2n=40. Figs. 2-3, tumor cells showing 76 and 77 chromosomes respectively.
SV = small V -shaped chromosome, MV = medium V -shaped chromosomes,
LV = large V - shaped chromosome.

smaIl. The number of these elements is shown in Table 2. The smalI V
shows a wide range of variation in number. The smalI V's are probably
only small rod-shaped chromosomes temporarily transformed. The large
V-shaped chromosomes seem to be double elements derived from two longrod-like chromosomes attached by kinetochores. Such chromosomes occur
in about half the observed ceIls. Giant chromosomes, with three or fourarms, are formed possibly by attachment of the kinetochores of three orfour long chromosomes; such chromosomes are observed only rarely inthe tumor celIs. V-shaped chrom03omes of middle size may be observedin almost all tumor celIs, numbering usualIy one and rarely two or three.
These chromosomes seem to have a submedian fiber attachment. I haveno idea of the origin of these middle-sized V-shaped chromosomes. They
seem to be among the essential components of the chromosome complex
14•

of the strain cells of this tumor. Also, small dot-like chromosomes, aswell as chromosomes with trabants, may be found. The origin of theseelements is not clear for the present.
In short, there are definite strain cells characterized by tetraploidy andby having middle-sized V-shaped chromosome in their nuclear complements.

3. Karyological Study on the Tumor Cells of the Ehrlich
Ascites Carcinome in Mouse
Although several papers on the chromosome complex of Ehrlich ascite
tumor of the mouse have appeared, no precise report of the chromosome
morphology has been published. The present ob~rvation has been performed on the cells in this tumor developed on mice received from Prof.
T. MIYAZI of Osaka University.
(1). Frequency of tetraploid cells: LEVAN & HAUSCHKA (1952) haveobserved the chromosome complex of tumor cells in the Ehrlich carcinome,
and pointed out that cells in this tumor show a very wide range of variations in chromosome number, with the mode at the tetraploid number(2n=4x=80). The author's reexamination has revealed the results presented in Table 1. The tetraploid cells form 96 per cent of the total showingthat the strain cells ("germ-line" in Levan & Hauschka's terminology)
are of a tetraploid nature.

..

Figs. 1-2. Chromosomes of tumor cells in the Ehrlich ascites carcinome.
1,79 chromosomes, 2, 80 chromosomes. V = V -shaped chromosomes.

(2). Chromosome number of the tumor cells: The chromosome numbers counted in 24 metaphase plates are shown in Table 2. The numbers
show a wide range of variation, the cells having about 80 chromosomes
being most numerous.
(3). Chromosome analysis of the tumor cells: The strain cells arecharacterized by having a tetraploid chromosome set. The chromosome
complex of these cells is characterized by the presence of a V-shaped
15

chromosome. One (rarely two) of this element has been observed in almost all tumor cells (Table 2). It has an appearance very similar to the
middle-sized V-shaped chromosome in the Takizawa quinone carcinome in
the mouse. Exceptionally, small or large V-shaped chromosomes, likethose seen in the quinone carcinome are also found. They seem to represent merely a temporary abnormality, as in the case of the quinone
carcimome.
( 4). Frequency of normal mitosis in the tetraploid cells: Relative frequencies of the division-type (cells undergoing regular mitosis), the aberrant-type and the disintegration-type mitoses occurring in the tetraploid
Table 1. Frequency of tetraploid cells occurring in the
Ehrlich ascites carcinome.
Diploid (±2n)
Frequency

8

303

%

2.5

95.6

6

1.9

. _ - - ._ _ - - ..

Table 2. Chromosome numbers of the tumor cells, and the numberof V-shaped chromosomes occurring in these cells.
No. of chromo

I

No. of V chromo

No. of chromo

I No. of V chromo

77

1

2
1

132
94
89
89
86
84
80(3)
79
78(2)

77

'!

74(4)
73
72
68
67
58
51

1
1
1
1
1
1

1
1
1
1
1

--_ ..

Remarks:_----- - - -Figures in parenthesis denote the number of observed cells.

Table 3.

Frequencies of division-, aberrant- and disintegrationtypes occurring in tumor cells.

I

Types

Division

Aberrant

Disintegration

Frequency

271

76

47

396

%

68

20

12

100

16

Total

cells were observed daily in a tumor mouse throughout its life span (12days in this case). The results obtained are given in Table 3. The totalfrequency of the division-type cells was 68 per cent, showing that mostof the strain cells multiply with regular mitoses.
From these results, it can be concluded that the strain cells in the Ehrlich
carcinome have a tetraploid nature, with 80 chromosomes or thereabouts,
actively multiply by regular mitoses, and are characterized by the presenceof a V-shaped element in the chromosome constitution.
1.

Is There Any Cytoplasmic Effect on Unstable
Genes in the Silkworm?
(Report by Yoshimaro TANAKA)

As has already been reported (TANAKA, 1951, 1952), there are several
subtypes, or distribution types as they may be called, with regard to thenumber of spots (the multilunar and multistar markings) and protuberances(in the knobbed strain). These subtypes are evidently under the control
of modifiers. The major genes, L, ms and K are constant to a considerable
degree, while the modifiers are highly unstable, so that one subtype may
be shifted to another in the course of several generations of selection.
The term" unstable genes" used to designate such modifiers has a somewhat different sense from the term "mutable genes". If selection toboth the plus and minus directions is effective in the case of a mutablegene, I would call it an unstable gene.
The cause of unstability of the modifiers in question is not yet known.
To see if the cytoplasm has any phenotypic effect on the mode of distribution of L- and ms- spots, several reciprocal crosses between the normal
and some multilunar and multistar subtypes were made, and the F 1 offspringwere examined for the characters.
A) Reciprocal Crossing in the Multilunar Strains(a) Reciprocal crossing between L4 - 10 subtype and the normal (+L)
L4 - 10 is a subtype in which the brown spots are most numerous, i. e.
they are present on the dorsal side of every larval segment. This type isthe most stable among all the multilunar subtypes.
The variations among F 1 phenotypes were nearly alike in the reciprocals.
No L 4 - 10 larvae appeared, as was expected from the previous experiments,
the larvae belonging to L 4 - S, L4-506oios and L 4 05 o6 • S being most numerous.
These subtypes altogether made 98.7% of the F 1 in L 4 _1Q"9-x +LC;-, and97.2% in the reciprocal cross, while the numbers of subtypes were 4 in
the former and 7 in the latter. The L 4 - 10 strain used in this crossing was
somewhat peculier; it segregated multilunars and multistars and non-multilunars in a ratio of 1: 1 in the F 1 of L 4 - 10 £f'. x +LC;-, and 2.4: 1 in the17

reciprocal cross. Whether this difference is merely accidental or not, must
be ascertained in the future.
(b) Reciprocal crossing between L 5 • 6 • 8 and the normal (+L)
The reciprocals again gave similar results. About 79% and 72% of theF l were multilunars in the cross L 5 .!i.8Sf. x +L~ and in the reciprocal respectively. The L 5 • 6 • 8 and L 5 .!i'8 subtypes together made up respectively 98.3
and 86.0% of all multilunars. One thing to be mentioned here is that thelarvae provided with brown spots on segment 4 were as numerous as 15(14%) when L 50608 was taken as the female parent, while only a single
larva had spots on this segment in the reciprocal cross.

'

A

B

Fig. 1.

c

..

~

E

D

F

G

H

Normal marking (A) and multilunar subtypes (B-H)

A:

Normal; numerals designate consecutive segment numbers from 1st
thoracic to 9th abdominal segments
B: L 4 - l0
C: L 4 - 8
D: L 4 •5 •6 .i'8
E: L 4 ' 5 ' 6 ' 8
F: L 5 ' 6 ' 8
G: L 5 .!i'8
H: L 5 ' 8(c) Reciprocal crossing between L 5 ' 8 and the normal (+L)
The normals used in this experiment were taken from the same batchas those used in (a). The result was practically the same as in the preceding experiment, namely, L 5 • 8 made up only 3.2% of the F l of the crossL 5 • 8 Sf.X +L~, and 3.6% of the F l of +LSf.x L5'8~, while the L 40506 • 8 subtype
was reckoned as 61.5% and 46.6% respectively. There were observed
161 (86.1%) and 253 (75.5%) larvae provided with one or two brownspots on segment 4, in spite of the fact that they had been entirely absent
in the multilunar parent. This may be accounted for by assuming thatthe modifier controlling the spots on segment 4 was introduced by the+L parent.
B) Reciprocal Crossing with a Multistar Strain
The multistar strain used was ms 6- l0 , and the normal +71" +1> (p 22).
As the multistar character is recessive to normal, the Fl's were largely
18

normal. The phenotypicaJly normal marking occurred in 87.5% of theF 2 of the cross ms £f.x +msc!), and in 81.4% of the F 2 of the reciprocal
cross, the rest being typical ms larvae. Possibly these normals include
real normals (+ ms) and mss individuals. These two types are phenotypicaJly indistinguishable, as both are provided with a pair of star spots on
segment 8. Distinction can be made only by breeding: real normals give
only normal offspring, while mss produces various ms-subtypes, beside
mss, in later generations.
The variability in numbers of star spots was somewhat lower in theoffspring of the cross ms£f. x + msc!) than that in the offspring of theother cross.
C) Conclusion
In all the crossing experiments described above, the variability of thecharacteristic spots in F 1 or F 2 progeny was always higher in the casewhen the normal was the female parent than in its reciprocal cross. The
data are still insufficient for deciding whether the difference is statisticallysignificant or not.

2.

SjJ<mtaneous Recurrent Mutations of a Modifier of the
M ultistar Marking(Report by Yoshimaro TANAKA)

In batch No. 512p41, a single larva with a star spot on one side ofsegment 4 appeared. This was the first case of a larva with any star spot
on the 4th segment in this pedigree through more than 30 generations.
Since then, a munber of larvae of the same type were observed in eachof the five subsequent generations, except 521msll, as shown in Table 1.
Table 1. Spontaneous mutants appeared consecutively-_._-~chNo.

Spot ----~~

(4)
(4)
(4)
Totals512p41

513p41

521ms11522ms11523ms11

238

105

511

35

56(tl

lltl
0
239

5*
0
110

0
0
511

5(t)
l<t)
41

37<tl
32<t>
125

----------

*
t
(.4)

Laid no eggs
Died in the larval or pupal stage
No star spot on segment 4( 4 ) One-sided spot on segement 4( 4 ) Paired spots on segment 4
The thick type shows the subtype from which the next generation was derived.

19

oNotwithstanding the fact that each generation was derived from (4)type parents, (4)- and (4)-subtypes appeared repeatedly in four consecutive
generations, and the frequency of mutants apparently increased graduallyin later generations.
There seem to be two alternative interpretations possible in this case.
o•First, a mutation pressure in the direction of (4)-->(4)-->(4) has gradually
increased as the result of some unknown cause. Second, some polygenes
causing the development of (4)- and (4)-types have accidentally accumulated
in this strain as a r~sult of inbreeding. Which of these two interpretations
is more appropriate cannot be decided for the present.
3.

Studies on the Semi-allelic E-series in the Silkworm(a) On the relation between Ell and EKP(Report by Mitsuo TSUJITA)As a result of heterozygosity of the Ell gene, EH/+, extra-semilunar
patterns appear on the 4th abdominal segment (Text-fig. A, B), whilewith heterozygosity of EKP, Ek P/+, extra-abdominal legs are formed on
the 5th segment (Text-fig. C, D). The larvae homozygous for EKP haveextra-semilunar patterns on the 6th segment, besides the above-mentioned
extra abdominal legs. The larvae with the genotype EH/EKP have a
combination of the characters peculiar to EH and EKP. It has been believed that these genes, as well as more than ten others, form a multipleallelic series, and that no recombination occurs among them. The writer(1952), however, has found cases of recombination of EH andEKP. The
results of the experiments carried out during the past two years are
summarized in the foIIowing:From the cross wild (+)XEH/EKP, a few EHEKP/++ larvae invariably
appear with the recombination value 0.7%. The larva with this genotype
represents a new type characterized by having extra abdominal legs on
the first and second abdominal segments, as well as extra semilunar
patterns on the first abdominal segment (Text-fig. E, F). Thus, the genes
EH and EK P furnish a good example of the so-called position pseudo-allelism(Lewis 1952).
As reported last year, a small number of EH and EKP larvae appearedin the cross + XEllEKP/++, with the recombination value also of 0.7%.
From the reciprocal cross a very small number of individuals of the genotype EH/+ and EKP/+ segregated. The fact that crossing-over occurs in
the female suggests that there is some chromosomal aberration at the E
locus of chromosome VI. In the sib-mating of EHEKP/++, three typesof individuals, i. e. EHEKP/EIIEKP, EHEKP/+ + and +, segregated in theratio of 1 : 2 : 1.

20

All of the F 1 individuals from EH EKP/EHEKP X + or from the reciprocal
cross have extra abdominal legs on the first and second abdominal segments and extra semilunar patterns on the first abdominal segment.
The larvae homozygous for the genes Ell EK P have supernumerary patternson the 4th and 6th abdominal segments, and two pairs of abdominal legs
A

c

B

D

E
F
G
H
Fig. Dorsal and lateral views of larvae with the genotypes,
H/+, Kp/+. HKpj++ and HKp/Hkp.
A: Hj+,
C: Kpj+,
E: HKpj++,
G: HKpjHKp (dorsal view)
B: Hj+,
D: Kpj+,
F: HKpj++,
H: HKpjHKp (lateral view)on the 4th and 5th segments. The latter are so well developed that innewly hatched larvae they look like normal abdominal legs, although inthe full-grown larvae they are usually smaller than normal legs (Text-figs
G, H), because of the retardation of their growth. The claws of the21

abdominal legs look almost normal, but they have little or no grasping
power. The homozygous individuals are weaker than the heterozygotes,
and the adult moths almost lack the ability to copulate; their legs areapparently paralyzed, and keep their proper posture with great difficulty.
This behavior is similar to that of moths anaesthetized by DDT. Dissection of such moths has shown deformity in their posterior ganglia.
It is clear, from the facts mentioned above, that Ell and EKl' are notreal allelic genes. In order to make clear which of these genes occupies
the terminal position in the chromosome, the recombination values between
E" and between EK1' and Nc have been estimated; Nc is knoW11 to be at thelocus 1.4 (Itikawa '48). However, I could not obtain clear-cut results, mainly
because of the interference of gene Nc with the penetrance of Ell or EKl'.
Under favorable conditions, for example at a temperature of 23-25°C.
and humidity 75-78% in an ordinary rearing room, the eggs with the
genotype Ell EK1'/ + +, when treated with diluted hydrochloric acid, showa high hatching rate. Under less favorable conditions, for example at thehigh temperature of 27°C. and dry air with humidity 50-60% in thermostat,
the same eggs show very low hatchability. Accordingly, in the F 1 of thecross EIlEKll/++ x +, the larvae heterozygous for EHE K 1 are much fewer
in proportion than the normal larvae. We are now planning to apply thisinteresting finding to practical breeding.

.

J

(b)

On the relation between g'ls and ENc(Report by Mitsuo TSUJITA and Bungo SAKAGUCHI)

The ancestor of the strain EellS was discovered as a mutant among the
hybrids between Japanese No.8. and Chinese No. 107. This mutant has
duplicated star patterns on the 7th and 8th segments, or on the 8th and9th segments; some individuals may have the patterns on all the 7th,
8th and 9th segments. The character is dominant. Embryos homozygous
for this gene have supernumerary legs on the 10th and 11th segments(Text-fig. A), and they die in later embryonic stages or immediately after
hatching. However, the penetrance of this gene for the supernumerarylegs is low. The individuals hetrozygous for this gene have lower vitality
than the normal ones, and they often die within the egg shell.
ENC is also dominant, and the larvae heterozygous for it are characterized by having duplicated crescent patterns on the dorsal side of the 5th
and 6th segments, and lacking the star markings on the 8th segment.
Embryos homozygous for this gene also die in a later stage. They areprovided with thoracic setae on all segments, and are incapable ofblastokinesis (Text-fig. B).
ENS develops neither star patterns on the 8th segment nor does it show
any lethal effect.
ENS and EMe show a clear distinction from each other in the development22.

of the embryo. In the sib·mating of EMS/+ or from the cross EAlSx
normal or normal x EAlS, a very few larvae with the phenotype EMC or
ENS appeared. The number of these unexpected types which have appeared during the last three years from 1950 to 1952, is as follows:
Table 1. Record* of appearance of EAlC and ENS individuals in the batchesof EMS or from the cross between EAlS and the wild type
Rearing year
and season

Mating INo·1 + IEAlSIENSIIEAlC Sum'50 Spring

Ms x ++ x Ms- - 1 - - --,~--'50 Summer'51 Autumn'52 Summer

2 141 50]
3 151 891/
5 18 50
MsxMs
2 94 171/
3S4 15 201
1/
4S3 109 183
Msx +1 163 75
1/2 324 124
1
3,
Msx+
87 167,+xMs 1 21 251 1011
+xMs! 2: 49, 32

I1-~------.""'~'--

2 194
1 243
1 70
1 112
1 217
1 293
1 239
1 449
1 255
1 354
2 85

1,
I
2,
1

11
21

EMc+ENs x 100 I Appearance
rate of EMC
Sum
1.5%
1.2
2.9

I

i
!

,
1

!

0.6
4.7

,

1.0%
0.4
1.4
0.9
0.5
0.3
0.4
0.2
0.4
0.3
2.4

I

* ThiS IS the record of the batches which produced the EMC individuals
among many EM S batches reared in the last three years.

ill

As shown in the table, the rate of appearance of ENS or EMC individuals
varies from lot to lot.
EMS appears in the batches of EMC very rarely. Out of the many batchesof EMC reared during last three years, 1950 to 1952, one EMS larva was
obtained as shown in Table 2:
Table 2.

Appearance of a single individual with the gene EMS in abatch of EMC from the cross + x EMC

Rearing year andseasonMating'52 Summer

+xMc

----

No.
- --------

3+

E,Jl:S

118

1

E·Jl:c Sum------

229

348

Rate of EMS%
0.3

It is thus evident that the so-called E-series occupies not a point locus,
but a section of chromosome of some extent, which has probably a complicated structure. Possibly this section consists of several genes withsimilar effects arranged in close sequence at the end of chromosome VI.
According to this view, it seems valid to assume that EMC is derived from
EMS by recombination, perhaps also with some position effect.
The question remains, however, as to why a change in the reverse
direction, i. e. from EMC to EMs, is more difficult to obtain. This may be
due to the fact that individuals heterozygous for this gene have lower

23

vitality than the normal individuals, and often die in the egg or in earlylarval stages.

Fig. 1. Embryo homozygous for EMS

Fig. 2.

4.

Embryo homozygous for EMe

Maternat Inheritance of "Lethat Yellow"(Report by Mitsuo TSUJITA)The gene" tem l " is recessive!. It has been known that embryos homozygous for this gene develop normally to black-colored young larvae anddie immediately after the 1st moulting. In the cross +/tem! x +/tem! or+ /tem! x tem/tem! the yellow lethal larvae can be recognized in the 2nd
instar 2 • In the cross tem/tem l x +/tem l or tem/tem! x tem/tem!, however, allhomozygous teml/tem! individuals die within the eggs which show throughthe semi-translucent shell the yellowish-brown dying larva. The maternal
inheritance of "yellow lethal" is shown schematically in figure 1.
The yellow-colored teml/tem! larvae immediately after the 1st moulting(E in fig. 1) cannot chew up mulberry leaves, because of incomplete
hardening and imperfect differentiation of the mandibular cuticle, and starve
1. The designation" lem!" corresponds to "ly" in my previous report (1951).
2. The three genes, +, lem and lem l form a multi-allelic series with thedominant-recessive relations + >lem>lem l •24•to death (UMEYA and TSUJITA 1951). The young temlltem l larvae developed
from eggs laid by a temltem l female moth (I in fig. 3) cannot even chew
through the chorion. These larve, when liberated from the eggs by cutting

Hatring------------Di~6.-----­•..---lst-moulting------ - - - - -

E

f )
C)

t )
.1

•

Dies

Fig.

3.

Fig. 3. Schematic representation of the maternal inheritance of "yellow lethal".
On the left side: A, + /lem l 'i'; B, unfertilized lem l egg laid by + /lem l 'i' ; C, egg
fertilized by a lem l sperm; D, black young leml/lem l larva; E, lethal yellow larva
directly after 1st mouting. On the right side: F, lem /lem l 'i' ; G, unfertilized lem l egg
laid by a lem/lem l 'i' ; H, egg fertilized by a lem l sperm; I, yellow young larva dying
inside the egg. The two lem l sperms produced by + /lem l 0 and lem/lem l 0 are
shown in the middle. Black and white background indicates the difference between
the ooplams derived from the two kinds of mothers and the difference between the
sperm plasm derived from the two kinds of fathers (+ /lem l and lem/lem l ).

25

through the shell, show a normal appearance, and move about actively,
but cannot feed on mulberry leaves and consequently starve to death.
It is assumed that the cause of the death of the young larvae within theeggs is the same as in the case of the moulted lethal larvae, namely, incomplete hardening and imperfect differentiation of the cuticular layer ofthe hypodermis, especially that of the mandible.
The maternal inheritance of "yellow lethal" may be due to the presenceor absence of some diffusible chemical substance, such as a precursor ofpigment, in the ooplasm derived from the mother. It seems probable that
there is some intimate relation between the production of the black (melanin)
and yellow pigments, and between the formation of melanin and the hardening of the cuticular layer of the hypodermis. The young normal lem!llem!
larvae developed from the eggs of the + Ilem! female (genotype wr!w1 ) areblack, while the lem!Jlem! larvae developed from the white eggs of the leml
lem! female are distinctly yellow. This fact suggests that the formationof pigments such as melanin and xanthopterin-B is somehow related tothe tryptophane metabolism.
In order to clarify this relation, biochemical experiments were carriedout. The results presented in the next report were obtained last year.
Table 3. Comparison between 'lethal yellow' and 'red' larvae
OrgansLethal yellow larvae

Head color

I-

Mandible

Red young larvae--Iyellowish brown
--

-

brown

-----

-

light yellowish-brown,
brownish at the apical
. end

-----

- - - - - - - _.._ - - -dark brown, deep darkbrown at the apical end------"--

Maxillayellowdark brown

Ocellidark browndark brown

Labrumyellowish brown---- - - - - _..

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

- - _..

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

Body surface_.- --_ _----...

..

Claws

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

reddish brownlight yellowish brown,
1st seg. yellow_._------- - - - - .

Thoracic legs &abdominal legs_-

dark brown- - - _ .. - - - - - . _ - - - - - , . _ - - - - - - - - --- - - -dark brownyellowfl-li;ht
yel-Iow,slightly
brownish---dark brown----~------I
stigma ring and entrance
Stigmata

to trachae yellowish brown
Setae

I whitish

stigma ring black, entrance
to trachae blackish brownlight brown

26

The lemlilem l eggs (H in fig. 1) may be called "Lethal yellow eggs",
They resemble the "red" strain not only in the external egg features in
the pigmentation period, but also in the color of the young larva (I infig. 1) inside the chorion, as shown in the table.

5. Genetical and Biochemical Studies of Yellow Lethal Larvae(Report by Mitsuo TSUJITA and Bungo SAKAGUCHI)•/I

Materials and methods:-Embryos of the normal (+) strain, larvae ofthe lethal yellow directly after the first moulting (designated as lem l),embryos of the same strain dead within the egg (designated as lemle)
and WI/WI larvae from white eggs (designated as lemle·w l ) were used asmaterials. The embryos or larvae were extracted in 80% methanol, 10-15%
acetic acid, 10-20% alkali, or in other solvents. Paper-chromatographicalanalysis of the extracts obtained by centrifuging or by sucking filtration
were used for the detection of pigments and amino acids.
As solvents, buthanol-acetic acid, phenol, sodium citrate and pyridine
were used. Fluorescence analysis of pigments by ultra-violet rays, andamino acid detection by means of ninhydrin reaction were carried out.
All treatments, extraction, spreading and drying, were carried out in adark room. Synthetic leucopterin, xanthopterin, isoxanthopterin and riboflavin were used as controls.
Experimental results:--Yellow pigments contained in the lem l have a
distinct spot near Rf 0.40 like the yellow pigment contained in the hypodermis of the lemon larva. When subjected to photolysis, this coloring
matter has almost the same Rf value as xanthopterin, and turns blue.
Moreover, its fluorescent color changes according to the change in pH
value. From these facts it can be safely concluded that this pigment is
xanthopterin-B.
Next, eggs of each strain in a later stage of incubation were dried, and
0.3 g. of the dry matter were extracted in 5 ml of 10% acetic acid or in
80% ethanol. The extracts, condensed to about 0.5 ml by the depression
method, were examined to determine the relative amounts of isoxanthopterin and xanthopterin-B. The relative amounts of isoxanthoperin in thesestrains have been shown to be +>lem>lem l >lemle· WI. The relative
amounts of xanteopterin-B tended to be the reverse, Le. +<lem<lem l<lemle·wl •The amount of xanthopterin-B is apparently greater in the lemlilem lembryos developed in the white eggs (WI). This fact indicates that thepresence of kynurenin has some relation to the formation of xanthopterin-B.
A substance of unknown nature has been recognized in the eggs of lem l
and lemle. This substance produces a faint bluish fluorescence near Rf
0.67.
27

In order to detect the various kinds of amino acids and their relative
amounts in each material. 0.3 g. of eggs in the later incubation period
were examined by the two-dimensional paper chromatogram method.
About twenty different amino acids were detected, including tyrosine,
proline, glutamic acid, glutamine, aspartic acid, cystenic acid, methionine,arginin, taurine and 19-alanin. These amino acids showed differences intheir relative amounts from strain to strain. Above all, the methionine
reaction was rather weak in + and lem eggs, and very strong in lem l
and lem1e eggs, especially in the latter. The significance of this finding
is not clear as yet.
It is inferred, from the results described above, that the important factors
which determine the differences among the materials. +, lem, lem l andlem1e, are the difference in relative quantities of xanthopterin-B, isoxanthopterin and substances related to these pigments.
We are planning to pursue further biochemical studies in these strains.

6.

Trisomic Silkworm Produced by Treatment with BHC Powder(Report by Mitsuo TSUJITA)

In a previous report (Annual Report No. 1 1950) the production oftrisomic silkworms (PS/PM/ + P) by treatment with BRe powder was recorded.
The trisomic nature of the six individuals obtained in this experiment has
been deduced from the facts that in the F 1 of their cross (carried out inboth directions) with wild, segregation occurred so as to produced fourkinds of larval patterns, namely, wild, striped, moricaud and striped-moricaud, and also from the observation of a trivalent metaphase figure of
the first spermatocyte division.
There remains, however, the question, why the segregation of the fourtypes occurred in a ratio nearly conforming to 1: 1 : 1 : 1, as shown in
Table l.
ff disjunction of the chromosome in the trivalent had been normal, thestriped larvae (ps/+P and pS/+P/+P) and the moricaud larvae (PM/+P
and PM/+P/+P) should have been twice as numerous as either the stripedmoricaud or the wild. This is not the case with the results shown in
the table.
Another interpretation might be considered as plausible, namely, that achromosomal fragment containing the locus ps or pM had been translocatedto another chromosome. Further experiment, however, has shown that
this is highly improbable.
In order to solve this problem, possible linkages between ps and Y, or
between pM and Y, in the chromosomes of the strain in question were
tested. Two strains with different genetic constitutions were obtained,

28

Table 1. Segregation in the cross pS /pM / +P x +P and its reciprocal
Mating typeNo.

_-pS/p."/+P x +P

Wild

StripedMoricaud..

.......

~"-_.'--~------'

109
184
117
108
110
47
93

1
2

3
4
5
6
7
- -

-

Total

---~_.

__._--_ .. _-

100

I-

91
149
114
143
102
95
85

96
119
94
49
72

381
517
401
454
390
193
358

588

743

650

2699

87
117
124

95
97
118

378
409
478

328

310

1265

1~0

-

-

92
108
129

104
87
107

329

298

-

- -

~----

I

- - - --

Total

Total

----

---.

718

8
9
10

-

81
114
74
84
84
43
108

-- ------+P x pS /p.1l +P

StripedMoricaud

--

I

-

-

pSYJPMyJ+Py and pSyJPMyJ+Py .

The difference between these two strainsconsists only in the location of Y on the chromosome ps or pM. Fromthe experimental results presented in Table 2, complete linkage in thefemale has been confirmed either between ps and Y, or between pM andY or between +P and y (Tables 2-3).
Table 2. Segregation in the cross pSY/pMy/+Pyx +P y==N=o=.==C===+=p=y===;I_~_~__ -~p=s==~~~=_=j'I=

6

86
86
96
86
109
62

Total

525

1

2

3
4

5

~

pM y
~

,

88
113
80
93

92
79
73
76

•.

r psp~y· .! ==T=o=ta=l==
I

~

~

91
67
86
63

357
357
325
341

5:: --I--4::--f-- -4-:-:-- ---2-:-::--

Table 3. Segregation in the cross +PyxpSy/pMY/+Py

_~_.

~py

1
2
3
--T~t~-I

I

p_s~

pMY

137
101

112
102

103
98

125

121

363

335--- - -

I _ _

pSpMY

Total

118

III
105
123

463
406
487

319

339

1356

-------'---------'------

29

The recombination value is very similar in the male either between ps Y,
pMy , and +1'y , for the individuals with the genotype pSY/PMy/+1'y or
between pSy, pMY, and + P y for the individuals, with the genotype
pSy/PMY!+l'y, being 1.56 in the former and 1. 77% in the latter (Tables 4-5).
Table 4. Segregation in the cross +l'y x pSYjpMy j +Py
--

pS

+1'

No.

_..

-

y

y

Y

78
63
83
76

4

y

Y

I

300

79
65
70
70

1
3
1
3

0
0
1
1

- - - ----

Total

--

-

-----

1
2
3
1

288 -7'1

284

Total

Recombination value

310
278
302
277

0.65
1.80
1.99
1.81

1167

1.56

71

0
0
1

- -- -

8

2

__.-

Y

--- - -

---

80
70
76
62

.. '.

y

Y

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

1
2
3

pSp"[

pM

_--'.

75
67

_~_I~
1

I

277

Table 5. Segregation in the cross +Py xpSyjpMYj+P y

+P
No.

y

y

Y

130
101

Total

231

pSpM

_._-_ ..-

4

y

Y

Y

. - - -----

105
112

3
1

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

p.l[
:

y

I

Y

Total ! Recombination value

109
108

469
429

I - - , _ .. _ - - I - - - - -

--

1
2

I

pS

--,-

I

--'---

2
2

5
3

115 I
102
'

.

0
0

21714 -1 8 217To--- .. _ -

217

898
--

I

I

I

2.13
1.40
1.77

These values are much lower than the normal recombination value between ps and Y, namely, 25.6%.
The recombination value in F 1 either between ps and Y, in the individuals with the genotype pSY/+P y, or between pM and Y in the individuals
pMY/+Py , was examined in the cross between the trisomic and wild.
Complete linkage was found both between ps and Yand between pM andY (Tables 6-7).
Table 6. Segregation in the cross pSYx +1'
No.

Total

1
2
3

205
114
156

198
95
161

403
209
317

Total

475

454

929

- - - - - - ' - - - - - - - - - - - - ' - - - - -I- - ' - - - - -30•

Table 7.

Segregation in the cross pMYx +P

No.

pMY

+Py

Total

1
2
3

216
183
205

208
205
218

424
388
423

Total

604

631

1235

- - - - - . ,..

In the two reciprocal crosses the recombination value was 1.67 and 1.80%
respectively (Tables 8-9).
Table 8. Segregation in the cross +Pyxpsy------------cc======c'=-=-='~=="=~~-~~~~=.=-

No.
1
2
3

162
183
220

Total

565

•

I-~~~

i
I

4

;

2

T-

9 1_ _
10

3

Table 9.

189
192
189

3
5
2

57_0_ _

Total

Recombination
value

358
383
413

1.96
2.09
0.97

~_-_-_i_I-5~4~~_'_-==~_-I_-._6_7

Segregation in the cross +Py x pMY----------

--

pMY

pMy

+P y

+PY

I
----

Total

I
2
3
4
5
6
7

156
183
149
209
115
180
179

5
4
8
1
0
7
5

175
199
180
197
136
210
227

3
2
2
2
2
3
2

339
388
339
409
253
400
413

Total

1171

30

1324

No.
----

. ----

-

-I--

_

----

16

I R~~~bination
value
I
2.36
1.55
2.95
0.73
0.79
2.50
1.69
- - _ . - _.....

2541

_
~
.
_
-

1.80

---

The recombination value thus obtained is similar to that found for thetrivalent; it is considerably lower than the value in normal bivalents.
From cross pSY/+PyxP-IIfY/+Py, individuals with the genotype pSY/PMY
were obtained. In the F 1 hybrid wild (+P) xpSY/PlllY or pSY/PMYx wild(+P) only ps and pM individuals segregated, as shown in Tables 10-11.

31

r

Table 10.
No.

pS;'-

1

I 218

2

I

~

pSY/plllYx +P
pMY
225

~

Table 11.

+P x pSY/plllY

Total
443

86

N2

75

161

T~II :::~::_;
From the experimental results presented above, it can safely be concluded
that the strains in question are true trisomies. The observation that nearlya 1 : 1 : 1 : 1 ratio was obtained for wild: striped: moricaud : striped-morieaud
can be explained as follows:-The segregation of the trivalent chromosomes,
PS/PM/+P, can occur in the three different ways, pSPM<c---,>+P, pS+P<c-_>PMand pM+P <__ --'>pS. If the segregation mentioned first occurred more frequently than the other two, and nearly twice as often as the last, the experimental results can be understood. It is possible that there is an intimate
connection between the abnormal segregation of the trivalent chromosomes
and the factor inhibiting the crossing over between ps - Y or pM - Y.

7. Genetical and Biochemical Studies in the Eri-silkworm
a. On the nature of the Pigments in the ePidermal
tissues of the Eri-silkworm(Report by Bungo SAKAGUCHI)

Genetieal and biochemical examinations of the yellow pigments containedin the larval epidermal cells of the yellow strain were made, as follows:(1) The pigments contained in the integument in young larvae and thepigments in the hypodermal cells of the head of full-grown larvae wereanalyzed by means of paper-chromatography. Petroleum ether extractsof the integument and the hypodermal cells of the heads were prepared.
The extracts were observed with filter paper (Toyo No. 50, 45-50 em longand I5-18cm wide) and a linear chromatograph, about 10 em in length, wasformed on the filter paper on the level of about 10 em.
The solvent was washed first in sulphuric acid, and then in distilledwater. Carotinoid pigments from the yellow cocoon of the silkworm wereused as controls.
The analysis has shown the Rf value for light reddish-orange yellow to
be 0.3, for orange-yellow pigment 0.7 and for yellow pigment 0.95. Thesespots are often indistinct, as the sample is diffusible.
To confirm the results thus obtained, column chromatography was used.
The absorbents were deactivated calcium carbonate and deactivated alu-32•mina (Merck);* the former was used for the upper fraction and the latterfor the lower fraction in the absorption tube.
The pigment of the sample was extracted by petroleum ether into anabsorption tube; then the chromatogram was taken by petroleum ether.
The chromatogram showed various yellow zones at the calcium carbonate
fraction, and an orange yellow zone at the alumina fraction. After desolved from each of these colored zones by carbon disulfide, these pigments
were reacted by conc. H 2SO h conc. HCI, Fe 2 CI 6 and ZnCI 2 • These results
were presented by the specific coloring reaction of carotinoid pigments.
It seems clear from these results that the pigments were composed ofxanthophyll and carotin, which belong to the carotinoid pigments.
(2) Mter the yellow pigments from the integuments of young larvae had
been nearly completely extracted into distilled water or diluted acetic acid
(10-20%), the extract was analyzed by paper chromatography; a buthanolacetic-water mixture (in the ratio 4: 1: 1) and a pyridine 0.1% ammonia
mixture (in the ratio 75 : 15) were used as solvents. After the development of the paper chromatogram, the paper was dried and examined for
fluorescence by ultra-violet rays. As a control of this experiment, synthetic leucopterin, xanthopterin, isoxanthopterin and riboflavin were used.
The results of this analysis are shown in the following table:
Table.

Results of paper-chromatographical analysis of pigmentssoluble in water or in dilute acetic acid
Leucopterin Isoxanthopterin

Name of substance-- - ---

Riboflavin

Xanthopterin

0.35

0.38

o Yellow@ Sky-blue_ . ~ - -

0.23

0.10

Rf value---------------

Buthanol-acetic acid(solvent)
skin & headRf value
Pyridine (solvent)skin & head

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

0.11© Purple------,--~--~---_.-

0.23

0.70

- - - - - --,--~----,---

0.91

I
---I
o Yellow
I ~ Pale blue ©Dilute©
purplel Purple

I

The table shows that the hypodermal cells of Eri-silkworm larvae contain leucopterin, isoxanthopterin, riboflavin and xanthopterin, and that,when buthanol-acetic acid is used as solvent, the spot of isoxanthopterin
appears at a single point at Rf 0.23, but when pyridine is used as solvent,spots appear at two points, at Rf 0.23 and 0.70. These observations suggest that the coloring matter is composed of two kinds of pigments, ofwhich one is perhaps isoxanthopterin and the other a derivative of iso-

* oxide of aluminium
33

xanthopterin.
Comparing these results obtained in the Eri-silkworm with the results
obtained in the silkworm, little difference is found for pterin pigments,
but a considerable difference is apparent for carotinoid pigments. Thus,in some (but not all) strains of silkworm, the carotinoid pigments contained in mulberry leaves are able to pass through the mid-gut epithelium.
Moreover, the pigments contained in the blood can pass through the silk
gland epithelium in some of these strains. However, carotinoid pigments
have never been found to pass through the epidermal cells of the silkworm.
In the strain of Eri-silkworm used in this experiment, it has been confirmed that carotinoid pigments can pass through the mid-gut epithelium
into the blood, and that the pigments in the blood cannot pass throughthe silk-gland cells, while they can pass through the epidermal cells.
Thus, there is a marked difference between the silkworm and the Erisilkworm in the permeability of the tissue epithelia to carotinoid pigments.
Since the permeability of the epithelial cells is probably controlled by geneaction, the facts found in this experiment suggest some interesting problems regarding the permeability of the epithelia of various organs topigments.

E. CYTOLOGY OF SOME INSECTS(Report by Tosihide H. Y OSIDA)

1. Cytological Study on the Racial Hybrz'ds of Phz"losamia cynthia(Lepidoptera, Saturnidae)
Philosamia cynthia is classified into three subspecies, P.c. Walkeri, P.c.
Pryeri and P. c. ricini. Walkeri is distributed in China, Manchuria andKorea, Pryeri in Japan and ricini in the East Indies; Walkeri has somelocal races. The present paper deals with cytological investigations of thehybrids among these subspecies and races. The materials were derived
from the following sources :-Walkeri from Manchuria (designated as M)
and Korea (C), Pryeri from Kyushu (K) and ricini from stock which had
been kept in Formosa (E).
The chromosome numbers in M and C of Walkeri are 2n = 26 and n = 13,
and the chromosomes of these races are nearly identical in general appearance. K and E have the chromosome number: 2n=28, n=14, and there
is little difference between the subspecies in the shape of the chromosomes.
The hybrid CxM shows a karyotype 2n=26, n=13, and cannot be distinguished from that of either race C or M of Walkeri. All the hybrids
C x K, C x E, Ex M, and M x E show similar karyotypes consisting of
2n=27, n=13 (=12 bivalents+l trivalent). The hybrid MxK shows a34•peculiar tetrad formation, namely, 2n = 27, n = 12 (= 10 bivalents + 1 trivalents+ 1 tetravalent).
From observations of the tetrad chromosomes of the F I hybrids, it has
been surmised that the races having the chromosome set 2n=28, n=14
were derived from a race having 2n=26, n=13 by duplication of one of
the chromosomes. Also, M and K have a reciprocal translocation between
non-homologous chromosomes. Thus, the differentiation of the three subspecies of Philosamia cynthia is due to duplication and translocation ofsome chromosomes. The geographic races C and M of Walkeri havebeen differentiated presumably by the presence or absence of this reciprocal translocation.

2.

..

Multiple Sex-chromosome Mechanism in Rhaphidopalpa
femoralis (Coleoptera, Chrysomelidae)
The chromosome number of Raphidopalpa femoralis has been determined by the author (1952). The present paper deals with the sex chromosome mechanism in this insect. The chromosomes in the first spermatocyte are 29 in number. Among the second spermatocytes there are
two kinds of cells, one having 30 and the other 29 chromosomes. The
chromosome set in the first spermatocyte consists of a very large V-shaped
chromosome and 28 ordinary V-or rod-shaped chromosomes. The large
V is a trivalent consisting of one small and two large elements, as is clearlyseen in the side view of the metaphase of the first division. At anaphasethe large components usually migrate to one pole, while the small component goes to the opposite pole. In the second spermatocyte there areobserved two kinds of cells as expected, one having 30 monads and theother having 29 monads. The former cell contains two large elements
and 28 ordinary elements, and the latter one small element and 28 ordinary
elements. It is obvious that the two large components are Xl and X 2 , thesmall one is Y, and the 28 ordinary elements are autosomes.
The chromosomes of insects belonging to Chrysomeridae have been observed by many workers, such as HENKING, NOWLIN, SMITH, STEVENS,WIEMAN and YOSIDA. Most of the species of this family have haploid chromosome numbers from 10 to 17 (d. "A review of the chromosome numbers inanimals" by MAKINO 1950). Rhaphidopalpa femoraHs, however, has 29
chromosomes in the haploid nucleus, suggesting tetraploidy. In this connection it is noticeable that the X -chromosome in this species is duplicated.
The author (1944-1952) has found, by comparison of the chromosome sets
in some species of Coleoptera and Hemiptera, that the ratio of the total
chromatin volume of the sex chromosomes to that of the autosomes isnearly constant. The present study in Rhaphidopalpa gives anotherinstance confirming this general rule.
35

F.

POPULATION GENETICS OF SOME BUTTERFLIESAND A LAND-SNAIL(Report by Taku KOMAI)

1.

The Butterflies Colias and Neozephyrus

The paper recording the findings of the writer and his co-worker AE
on the genetics of the Pierid butterfly Colias hyale poliographus has been
published in 'Genetics', 38, No. 1 (1953). The manuscript of the otherpaper by the writer dealing with the population genetics of the Lycaenid
butterfly Neozephyrus taxila is ready for publication. This paper presents
the writer's observations on thirteen population samples of this polymorphic butterfly obtained from twelve localities in Honshu and one in Hokkaido. The essentials of the findings have already been presented (The
Annal Report, No.2).

2.

The Land-snail Bradybaena

During this year, as in the previous one, many specimens of the polymorphic land-snail, Bradybaena similaris, were obtained from a locality in
Nagasaki. The sample from this locality includes the type banded-brownish in larger proportion than that from any other locality. Laboratory
experiments are under way to test whether the genes for bandedness andbrownish color are allelic in the strict sense, or semi-allelic. Also, it isbeing examined whether there is any evidence of a differential viability
among the four marking- and color types of this snail.

G.
1.

GENETICS OF SOME CEREALS

Irradiation Experiments with X-rays in Einkorn Wheat(Reported by Seiji MATSUMURA)

As to the relation between the frequency of chromosome aberrations in
the PMC's of Triticum monococcum and the dose or wave length of Xrays, the results of experiments performed last year have been confirmed.
The data are shown in Table 1. The frequency of ears with chromosome
aberratiQns increases with X-ray dose, but not in a linear relation. It isalso fairly certain that the shorter the wave length of X-rays, the higher
the frequency of chromosome aberration. These facts can be explaind on
the basis of the difference in the distribution of ionization within the nuclei
and the chromosomes. When irradiated by hard X-rays, the majority of theresulting ionization is more scattered than in the case where soft X-rays are36.,

used. The chromosome breaks induced by hard rays are scattered here
and there on the same chromosome or on different chromosomes, so that
union of broken ends of different origin, or interchange, takes place moreeasily than in the case with soft-ray irradiation, which produces m~re closely
adjacent breaks, and is liable to give a high proportion of restitution.
Table 1. Relation between dosage or wave length of X-rays andfrequency of chromosome aberrations in T. monococcum~.

Voltage(KVP)

Dosage(r)!

~

No. ofobservedears

No. ofaberrations

No. of ears with aberrations(%)

6n+2r @+5n ®+4n* @+@+3n*------------~

Control
180
180
180
130
80

o( 0.00)

19
5,400
8,100
13,500
8,100
8,100

120
101
93
109
116

1

1
1

6
8
28
14
5

i
1
2

2

·1
I
I

7 ( 5.83)
14 (13.86)
32 (34.41)
15 (13.76)
6( 5.17)* Counted as two aberrations.

.

Many mutants were chlorophyll abnormalities: albinistic, yellow, virescent, striped, etc. There also appeared other mutations, such as: dwarf,
twisted, short-awned, narrow-leaf, early and giant. Most of these mutants
behaved like simple Mendelian recessives. Of these, the early and giant
mutants could be used for breeding purposes. The mutation rate of theX2-generation seems to depend not only upon the radiation dosage but also
upon the wave length.

2. Effect of Ultra Short Wave Irradiation on Einkorn Wheat(Reported by Seiji MATSUMURA and Taro FUJII)

Dormant seeds of Triticum monococcum were exposed to ultra shortelectric waves. Impulse waves were applied (wave length 10m) to remove
the heat effect, at 5,lOOv, lOmA current and about &In distance. Few
chromosomal irregularities were observed in the meiosis of the treatedplants (S1-generation). Among the progeny (S2) obtained by selfing of the
Scplants, however, there were found some dwarf plants, which were about
half as tall as the normal plants and highly sterile. In the progeny (S3)of the sister plants of these dwarfs, again some sterile dwarfs appeared,
but their height and fertility were somewhat improved. Crossing of thesedwarfs with T. monococcum and aegilopoides was unsuccessful. In theS4-generation recovery of fertility and plant height advance considerably37

further, and in the S5-generation, at last, no dwarfs could be found. The
mechanism of these phenomena awaits further investigation.
On the other hand, after the treatment of seeds of the same species
with supersonic waves, chlorophyll mutants such as albino were observed.

3. Cytogenetic Studies of Wheats and their Relatives(Reported by Seiji MATSUMURA)
Nullisomic dwarft and tetrasomic giants in their offspring Dr. SEARS
has been studying crosses between his own nulIisomics in Triticum vulgare
and the author's a'"'-'g-dwarfs. The latter are alsonullisomics which wereoriginated from the offspring of pentaploid wheat hybrids, Le. they were
deficient in a chromosome pair from the D-genome. SEARS' results haveshown that NulIi-XVI corresponds with my g-dwarf. The author's crossing
experiments, however, have revealed that chromosome XVI could correspond to no other than the f-chromosome, as already reported (comp. Ann.
Rep. No.2, p. 25). To solve this descrepancy between our findings, a
new NuIli-XVI kindly sent by Dr. SEARS has been pollinated with thea'"'-'g-dwarfs. From the cytogenetic study of these hybrids it has been
confirmed again that NuIIi-XVI corresponds with the f-dwarf.
The a'"'-'g-dwarfs have been crossed with T. compactum, in order todecide whether or not the compact gene C is located in the D-genome.
Also SEARS' nuIIisomics have been used as one of the parents in crosses
which attempt to find out what chromosomes are involved in the supernumerary pair of the tetrasomic giants which were originated from theoffspring of the a'"'-'g-dwarfs.
Agropyrum, a genus related to Triticum Among the hybridization experiments between Triticum spp. and Agropyrum spp., the cross between
T. vulgare (AABBDD) and A. glaucum (BBEEFF) has been successful.
Many Agropyrum species have been collected from several districts in Japanand from various foreign countries. Seeds of A. triticeum, an annual
plant having 14 somatic chromosomes, have been treated by colchicine, toobtain autotetraploids. The author is sceptical about the hypothesis of
McFADDEN and SEARS, that A. triticeum should have the BB-genomes.
H.

GENETICS AND CYTOLOGY OF NICOTIANA
1. Cytogenetical Problems in the Genus Nicotiana(Report F. A. LILIENFELD)The hybrid N. sylvestris x N. tomentosiformis and its amphidiploid were
investigated. At I. M. in the P.M.C.'s of the hybrid 0-5 very loosely38"connected bivalents are formed. The univalents show a pronounced
tendency to ward concentrating near the poles, where most of themundergo the further meiotic development and become included, without
division, into the respective daughter nuclei. A small number of univalents
approach the equatorial plate; these are often divided, and the halves
move toward the opposite poles. Non-reduction is not seldom. The
hybrid is quite sterile, but the pollen showed a small percentage of unreduced, large, healthy grains (1-2%). Their number was very variable;at the end of the flowering period almost none at all were observed. The
amphidiploid showed very good chromosome pairing, except for a rather
frequent occurrence of 1-2 univalents and a single tri- or tetravalent. In
spite of that it was, on the female side, completely sterile. The pollen
was highly fertile (86-92% good grains), and the single amphidiploid plants
showed an unchanging percentage of good pollen throughout the wholeflowering season. Seedlings obtained from a pollination of the variety
Dixie Bright with pollen of the amphidiploid were markedly stronger
than those obtained from selfed Dixie Bright. These findings are, in
general, in accord with the reports of other authors.
In order to explain the puzzling female sterility of the amphidiploid, sometime ago GREENLEAF postulated several complementary genes which act,
when brought together in the amphidiploid, as female-sterility factors. In
a kind of experimentum crueis, a series of crosses have been undertaken,
in the attempt to produce female-sterile sylvestris and tomentoszformis
and in search of a linkage between GREENLEAF'S putative sterility genes
and other genes.
A number of crosses were carried out between other' diploid species,
with the object in view of producing new amphidiploids and testing themfor their usefulness as breeding material.

2.

Irradiation Experiments with X-rays in Nicotiana(Reported by Seiji MATSUMURA and Taro FUJII)

Dormant seeds of Nicotiana sylvestris (n=12) and N. tabacum (n=24,
Bright Yellow and Dixie Bright 101) were exposed to hard X-ray irradiation,
which was applied at 180KVP, 3mA, without filter. The dosage was
5 ,000-50 ,000r. At more than 15,000r the irradiated seeds of N. sylvestris
did not germinate at all, and at 15,000r the germination rate in thisspecies was markedly reduced. In N. tabacum, Bright Yellow showed
higher tolerance against X-rays than Dixie Bright. The higher the dosage
above 15,000r the more delayed and uneven were the germination oftreated seeds, as well as the growth of the seedlings. At the highest
dosage, the germination rate of the seeds was reduced, especially in Dixie
39

Bright, from 78.75% in the untreated seeds to 6.00%.
N. sylvestris has usually 12 n in the PMC's. In most of the cases of
induced chromosome aberrations found in the treated Xl-plants, single
translocation (lIv+lOn), seldom lln+1}, lln+1I+fr., or asynaptic configurations have been observed. In N. tabacum rare occurrence of 23 n +2 I
and 24 n +fr., besides (1-3)Iv+(22-18)n caused by 1-3 translocations, hasbeen observed. Such induced aberrations also occurred more frequently
in Dixie Bright than in Bright Yellow. The frequency of chromosome
aberrations, on the whole, increased in a linear relation to the X-ray
dosage. In two or three inflorescences of the same plant, identical chromosome aberrations were always observed.
Among the Xrplants from seeds irradiated at 15,000r and at higher
dosage, various kinds of morphological abnormalities appeared, such as
narrow, shrivelled and variegated leaf. These characters seem to originate
from plasmic abnormalities. In the X 2 -generation many recessive mutants
were observed, such as small round, mottled, yellowish green, yellow
petiole, etc.
From these results it is assumed that adequate dosage of X-rays forradiogenetical study on induced mutations in tobacco is 15,000-30,000r.

3. Cytogenetic Studies on the Genus Nicotiana IV.
(Report by YO TAKENAKA)a) Reduction divisions in hybrids between N. glauca and the N. alatagroup.
The three species, N. alata (n=9), N. longijlora (n=lO) and N. plumbaginifolia (n=lO), were crossed each with N. glauca (n=12). The crosses
N. glauca x N. alata and N. glauca x N. plumbaginifolia gave someseeds, while no seed was obtained from the cross N. glauca x N. longiflora.
Of the reciprocal crosses, N. alata x N. glauca gave no seed, but N.
longiflora x N. glauca produced some germinating seeds.
The external characters of the hybrids which were produced from theseeds of N. glauca x N. alata and N. glauca x N. plumbaginifolia agreed
with Kostoff's description of those of the same hybrids. No report of
the hybrid N. longiftoraxN. glauca has been published, so far as I know.
The features of this hybrid were in agreement with Kostoff's descriptionof those of the hybrid of the reciprocal cross.
All the hybrids mentioned above showed considerable irregularities inmeiotic behaviour in the PMC's. Polysporous PMC's were often observed
and the hybrids were completely sterile.
At the first metaphase in the hybrid N. glauca x N. plumbaginifolia,
0-4 bivalents were counted with the mode at 2n .
40

..

In the hybrid N. glauca x N. alata, 0-7 bivalents were observed, andthe most frequent configurations found were 3n +151 and 4n +13 1•
In the hybrid N. longiflora x N. glauca, the number of bivalents was
1-6 and the typical configuration of the chromosome complement was
6n + 101, although the frequency of this combination was low in proportion
among the observed PMC's since polyvalents ranging from tri- to octavalents were often found. The chromosomes of this plant tended to be
sticky at meiosis, and the divisions were more irregular than those in
the above two hybrids. Such remarkable irregularities were not foundin the reciprocal cross made by Kostoff, or in the hybrid N. glauca x N.
plumbaginifolia according to Kostoff and Goodspeed, in which the paternal
parent was taxonomically closely related to N. longiflora.
These irregularities may be due to the difference in the degree of affinity
between the cytoplasm of the maternal plant, N. longiflora, and thechromosomes of the paternal plant, N. glauca, which was probably lower
in this direction of cross than in the reciprocal direction.
The above findings about the three hybrids suggest the presence of afew partially homologous chromosomes between N. glauca on one sideand N. alata, N. plumbaginifolia or N. longiflora on the other. Moreover,a few chromatids or chromosomes in diplotene and diakinesis showed
end-to-end junctions, and anaphasic chromosome bridges were always
observed.

b) Reduction divisions in hybrids between N. tabacum and three otherspecies.
The external characters of the hybrids N. tabacun (n=24)xN. sylvestris(n=12), N. tabacum x N. glauca (n=12) and N. glutinosa (n=12) x N.
tabacum agreed exactly with the description of Kostoff and many otherprevious investigators.
At first metaphase in the PMC's of N. tabacum x N. sylvestris, themost frequently observed chromosome configuration was 3m +9 n +91. Thisobservation largely agrees with Kostoff's. The meiotic figure mentioned
above suggests the presence of three pairing chromosomes between two
sylvestris genomes and the tomentosa genome.
At first metaphase in the PMC's of N. tabacum x N. glauca, the chromosome conjugation types were 0-4m , 3-lOn and 12-241• The former
two types suggest the presence of several homologous or semi-homologous
chromosomes between the glauca genome and the two subgenomes oftabacum. The chromosome behaviour at first metaphase largely agreed
with the observations of Kostoff and also of Sarana, while the omissionof the second division found by the present author is not pointed out by
the previous investigators.
In the PMC's of the hybrid N. glutinosa x N. tabacum, 1-7 bivalents
41

were observed with four bivalents as the mode. This is in agreementswith the observations of Kostoff and also of Miintzing. Accordingly, besidethe intersubgenomatic chromosome conjugation in N. tabacum, one ormore semihomologous chromosomes seem to occur between the glutinosagenome and the tabacum subgenomes.

c) Reduction divisions in hybrids between N. suaveolens and three otherspecies.
Reciprocal crosses between N. suaveolens (n = 16) and four other species,
N. gossei (n=18), N. alata (n=9), N. longiflora (n=lO) and N. plumbaginifolia (n= 10), were carried out. The reciprocal crosses between N.
suaveolens and N. gossei gave always many germinating seeds, while theother six crosses did not produce any seeds, with the exception of N.
suaveolens x N. longifolra and N. suaveolens x N. plumbaginifolia.
In the meiosis of the PMC's of the hybrid N. suaveolensxN. gossei, thechromosome configurations most frequently found were of the following
three types, 2m +14 n , 1m +15 n +1 1 and 16n +2 I . Besides, several polyvalents were occasionally observed, and many chromosome bridges wereseen at first anaphase. This suggests the presence of some inversions ortranslocations between the chromosomes of N. suaveolens and those of
N. gossei.
The study of meiosis in the PMC's of the two hybrids, N. suaveolens x
N. longiflora and N. suaveolens x N. plumbaginifolia, agreed very wellwith Kostoff's observations, the number of bivalents in the former being
0-3 and in the latter 0-4. Since the chromosome configuration 1n +24 1
was mostly observed in the above two hybrids, it seems that one pair ofchromosomes with long homologous parts in common is present among thechromosomes of N. suaveolens and N. longiflora or N. plumbaginifolia.
In the hybrid N. suaveolens x N. longiflora, the cells in the tapetum
tissue are considerably enlarged at an early stage of meiosis, and almost
all PMC's have degenerated and disintegrated befere the end of the reduction division, although the cause of this change is entirely unknown.

4. Genetical Studies on the Mid-rib Proportion and theLeaf-shape in Tobacco Plants.
(Report by Kan-Ichi SAKAI, Kanji GOTOH, and Shin-ya IYAMA)

Genetic analysis of the mid-rib proportion and the shape of leaf in the
tobacco plant was conducted on the hybrids between the varieties White
Stem Orinoco and Holmes of Nicotiana tabacum L. It has been shownin the 1951 experiment that the leaves in White Stem Orinoco are rather
elongate and slender and have a high mid-rib proportion, while Holmes
42has rather round leaves and low mid-rib proportion. Means and variancesof these characters have been determined in the PI' POl' F b F", and two
backcross populations, and are presented in the table.
---------- ----l\1id~rib-proportion**\-.... - Leaf shape
Mean (%CC-)-_·I-V~a-ri~a-n-c-e-.--Mean(96)-

Varianc~_

White Stem Orinoco
Holmes

38.35
25.69

3.4410·2.7093

38.74
63.56

10.141014.2227

FI *FlxW.S.O.
F I x Holmes

i

F

i

29.90
33.88
28.10
30.40

7.6176
7.463814.3868

63.85
47.82
58.75
53.20

47.4962.57.4716
85.7460_ _ _ _ _ _1

_ _2 _ _ _ _ _ _ _-'--1--'-____*) The variance of F I hybrid has not been determined because of an
accidental fault in the course of cultivation.
**) The mid-rib proportion in the table was measured in fresh leaves.
since it has been shown in the 1951 experiment that the correlation of
the characters between fresh and dry leaf is extraordinarily high.

On the basis of such determination, the variance due to additive genetic
effect (D), that due to dominance effect (H), and that due to environmental
effect (E) were calculated, and the heritability and the number of effective
factors were estimated for each character. The partitioning of such components of variance was made according to Mather.
___

D
H
E

l~i~~;ib proportion'.

Heritability in the broad sense
Heritability in the narrow sense
Number of effective factors

27.3844-9.4856
3.06600.787

Leaf shape
133.0484
28.5040
12.0958
0.859
0.776
1.15

The H value for the mid-rib proportion in the table is found to be
negative, suggesting a possible occurrence of linkage between effective
factors, or else, of some unknown influence of circumstances. It seems
necessary, therefore, to make further experiments with the F 3 population
before we come to any definite conclusion with regard to heritability in the
narrow sense and the estimation of the number of effective factors forthat character.
It may safely be inferred that of the genes controlling the mid-rib proportion, those for lower proportion behave as partially dominant, and of43

the genes controlling leaf-shape, the genes for round leaves show complete
dominance over those for elongate leaves.
The total and genetic correlation coefficients between mid-rib proportionand leaf shape were obtained for the F 2 population, as shown below:
Total correlation coefficient.
-0.52*
Genetic correlation coefficient
-0.57
*)

This value exceeds the 1% level of significance.

It has thus been found that the correlation coefficient obtained for theF 2 population agrees very well with that obtained from the variety trials
conducted in the preceding year.
It may be concluded from the findings given above, that the number ofeffective factors for the leaf shape is rather small, and that the heritability
in the narrow sense as well as in the broad sense, as to the leaf shapeand that in the broad sense as to the mid-rib proportion are so high inthe present cross, that the individual selection during the breeding procedure
will be quite effective for getting tobacco strains with round leaves andlow mid-rib proportion.

1.

GENETICS OF SOLANUM AND GAPSlGlUM

1. Genetic Studies on Eggplant (Solanum melongena L.)(Report by Kanji GOTOR.)

a. Regression analysis of quantitative gene action.
The majority of economic characters in the eggplant seem to be polygenic in inheritance. The experiment reported here was designed withthe purpose of determining the mathematical models fitted for analysis ofsome of the quantitative characters in this plant, and clarifying the dominance relations of their genes. By constant parent regression analysis
following Griffing's method, the model of gene actions on the shape andweight of the fruit, as well as of those on the period from seeding toflowering, was found, and the dominance relations of genes for the above
characters were examined. Moreover, the dominance relations of the genes
for bunchiness and hairiness, which are the characteristics of the variety
Burma, were also examined.
Seven varieties of eggplant and 18 of their F 1 hybrids were used asmaterial.
The results obtained may be summarized as follows:
1. There are arithmetically cumulative actions with negative dominancewith respect to the genes for shape, and the genes for the period fromseeding to flowering. The degree of dominance of the genes for shape44

is very slight. The degree of dominance is highly variable for thegenes for the length of the period between seeding and flowering; insome crosses even overdominance has been observed.
2. In the case of the genes for weight, a more adequate model of geneaction is logarithmic.
3. The genes for bunchiness show no dominance so far as the present
experiment is concerned, and the genes for hairiness show negative
dominance.

b. The heritability Of some quantitative characters and estimation o/theminimum number 0/ genes.
The present investigation has been undertaken to estimate the heritability of some of the quantitative characters in the eggplant, and theminimum number of the genes governing the3e characters. The charactersstudied were fruit shape, fruit weight, period from seeding to flowering,
fruit yield and fruit number per plant, bunchiness and hairiness. Six eggplant varieties and five of their F l and F 2 hybrids were used for this study.
The planting was made according to randomized block arrangement withthree replications. The heritability obtained belongs to the category in the
broad sense, and the environmental variance is represented by the varianceof Fl' The estimation of the minimum number of genes concerned wasmade according to Wright's formula.
Fruit shape, fruit weight, the length of the period from seeding toflowering, fruit yield and fruit number per plant have heritability averaging 89.3, 88.6, 69.6, 10.0 and 4.1 per cent respectively.
In the two crosses, Burma x Sendai-naga No. 1 and Turuboso-sen-nari x
Black beauty, the fruit yield and fruit number have given a negative
genotypic variance. The heritability of these characters is generally low,
and highly variable according to crosses. It may be concluded that theyield per plant in the F l generation is greatly influenced by both environmental condition and experimental errors. The largest minimum numberof genes concerned with fruit shape, fruit weight and the period fromseeding to flowering is estimated as 5, 9 and 4 respectively. It should be
noted, however, that the minimum number of genes thus estimated ishighly variable among the crosses, and that the estimated number of genes
for fruit weight is proportional to the differences between the parents.
The vigor in the F 2 for fruit yield and fruit number declines to 73.8~
74.0 per cent of that of the F l , taking the average of the five crosses.
In the cross, Burma x Sendai-naga No.1, the heritability of bunchinessand that of hairiness is 80 and 70.5 per cent, and the minimum number ofgenes concerned is 3 and 4 respectively.
The phenotypic correlation between the shape and fruit weight in fourcrosses, as well as among four characters, namely, length of period from45

seeding to flowering, fruit shape, bunchiness and hairiness, in the Burma x
Sendai-naga No. 1 are generally low. Thus, it may safely be surmisedthat the genes governing these quantitative characters are segregating independently of one another.
The pigmentation on the anther and the pigmentation of the lower
part of the calyx, which is a characteristic of the varieties Burma, Black
beauty and Florida high bush, are due to a pleiotropic effect of one andthe same major gene. In the Florida high bush x Sendai-naga No. 1 cross,association between the pigmentation and the three characters, namely,
fruit shape, fruit weight and the period from seeding to flowering, hasbeen confirmed.

2.

Inheritance of Fruit Color in Capsicum(Report by Toro ENDO)

By crossing of the two varieties, Goshiki and Takanotsume, of the pepper, Capsicum, the intensity of the color due to chlorophyll in the succeding generation and the extension of the colored area due to anthocyaninof the fruits were determined; they were found to be distributed in themanner shown in the table.
The intensity of the color due
to chlorophyll:'~U~:dePI (Takanotsume)
P 2 (Goshiki)pr.] 2! .
27

21

F[ (P2 XP1 )--

B 1 (It't x PI)
B 2 (F1 x P 2 )

-

-

14

I 7

F2

I·

The extension of coloredarea due to anthocyanin

31_4_-_,I-d_e~~~tall

Total

15

10 11731 I -

27
39
46

6
-

97
41

32
1

142
111

17*

26

13
29

20

24

53 I 17

121

7*

I·

6

3
106
10
44

36

39
7

20
1
34
66
44 i 24

39
46
144
110
119

* Including fruit which contained a trace of anthocyanin.
From this reault, the number of responsible genes was estimated by theformula n=(PI-P2)2/8(VF 2 - VF I ). It has been found to be 1.39 for the genes
for chlorophyll color, and 1.18 for the genes for anthocyanin color. It is,accordingly, to be inferred that there are one or two partially dominant
genes controlling the chlorophyll character and one gene of the same sortfor the anthocyanin character.
The anthocyanin of the pepper has been found by the writer, using
paper chromatographic analysis, to be the glycoside of delphinidin. This46

anthocyanin apparently has a tendency to be produced only in the part
exposed to the sun, while the carotenoid is produced first in the same partand later extends to the other sides of the fruits.

3. On Genes Controlling Quantitative Characters in
Capsicum annuum L.
(Report by Akira MIYAZAWA)
Two varieties of C. annuum, Taka-no-tsume and Chinese, which differ
distinctly in quantitative characters, were crossed, and the number ofgenes controlling fruit- and leaf-characters and the correlations among someof them were analysed. The experiment was conducted according to thecomplete randomized block design with three replications on the PI' P2' F l
and F 2 populations. Measurements of characters were always made after
they had ceased to grow. The characters measured were weight, length
and width of fruit, length and width of leaf, length of petiole and numberof seeds' per fruit. Estimations of the number of genes were made according to the CASTLE-WRIGHT formula. The genetic correlation was
calculated between two of these characters.
The results obtained by such analyses are presented in the table.
Table.

Showing the number of genes controlling the characters of Capsicum,
and correlation coefficient between some of these characters.
Number of genes

Lg. L.J
Wt. of Lg. of Wd. of, Lg. of I Wd. ofI Lg. of I No. of ! Lg. F.J
fruit
fruit! fruit I leaf : leaf ! petiole' seeds
Wd. F. I
Wd. L.
!
' "----,-'--- - "-"---,

52.24

0.79

9. 52

. 1. 59
I

I
'

,'I

7.92

I
I

0.04

I 6.51
I

1

I

1.11

5.63

Correlation Coefficient
Wt. F. vs. Lg. F. vs. I Wd. F. vs. I Lg. L. vs. I
No. S. ' Lg. L. I Wd. L.
Lg. P.
Lg. F.JWd. F. vs. Lg. L.JWd. L.
1I,--_.-"--

0.86**

0.81**

0.20*

0.73***) Exceeds the 5% level of probability.
**) Exceeds the 1% level of probability.
+) Abbreviations· ·Wt.: Weight; Lg.: Length; Wd.: Width; No.: Number;
F.: Fruit; L.: Leaf; S.: Seeds; P.: Petiole.

It is found that the number of genes controlling width in any of theorgans seems to be higher than that controlling length in the corresponding organs. It is also found that a rather high correlation exists between
weight of fruit and number of seeds per fruit. Between similar characters47

of different organs such as leaf and petiole, or fruit and leaf, high correlation is observed. The fact that the number of genes controlling lengthin each of the three organs is very small suggests a possible pleiotropic
effect of the genes. The correlation between the length/width ratio offruit and that of the leaf is low.

J.

GENETICS OF SOME FLOWERING PLANTS

1. Cytogenetic Studies on Sex in Cannabis sativa L. 11.
in Diploid, Triploid and Tetraploid Males.

Meiosis(Report by YO TAKENAKA)

Diploid males: In the meiosis of the pollen mother cells of the diploidmales, one unequal pair was clearly distinguished among ten bivalents. The
larger member of this pair is the largest of all the chromosomes. It is,however, difficult to distinguish the larger member in size and shape froma member of another large but equal pair.
Triploid males: The meiosis of male plants, which had been determined to be triploid (2n=30) by chromosome counts on the root tips, wasobserved. The chromosome complement of this plant had been assumed
to be 27a + X + X + Y from the chromosome complements of their parents,
36+4X and 18+X+Y. The chromosome conjugation at first metaphaseshowed very many trivalents and a few univalents :o univalents
among 10 PMC's
1
34 "

2

22

3

17

4

3

The chromosome configuration gIll + In + l r was the most frequent, andthe configurations 8Ill +2 n +2 r and 7 m +3 n +3 r came next. Often PMC'swith only trivalent were found. The V-shaped trivalents in each PMC
numbered from one to four, of which two were very large. One, composed of equal members, was probably an autosome complex. The other,composed of three unequal members, seemed to represent the sex-chromosome complex. In the latter, the chromosome situated at one end wasequal in size to, or larger than, the largest chromosome of the autosome.complex, and the two others, one at the other end and the other in the
middle, were slightly smaller. Therefore, the configuration of this chromosome complex may be considered as Y -X-X. Triploid intersexes also
showed the same configuration as far as the sex chromosomes are concerned, viz., Y -X-X.
Tetraploid males: In the meiosis of the PMC's of tetraploid male48

plants, induced by colchicine treatment, about ten chromatid groups were
found in the pachytene stage, whereas in diakinesis about twenty chromosomes were observed. Most nuclear plates in the first meiotic division
showed 18-20 gemini besides occasionally a quadrivalent or a trivalentaccompanied by a univalent. These trivalents or quadrivalent chromosomes
represent mostly the sex-chromosome complexes. The sex-chromosome
complexes are classifiable into four types; Y - Y, X-Y, Y -X-X-Y andY -X-Y, with the frequency 77, 29, 26 and 8, respectively, apart from a
few other types. Among the four types of sex chromosome complexes,
both Y - Y and Y - X - X - Y types would give only pollen containing X
and Y, while the X - Y type would give pollen with two X's or two Y's,in addition to that mentioned above, and the Y - X - Y type is expected to
produce four kinds of pollen grains, namely, those having two X's, twoy's, two Y's and one X, and only one X, respectively. However, suchpollen grains should form only a fraction of the total pollen. Accordingly, a cross between tetraploid females (36a+4X) and tetraploid males(36a+2X+2Y) would produce many tetraploid plants having the constitution 36a+3X+ Y, as pointed out by Warmke and Davidson.

2. Pigment Combination of Viola tricolor(Report by Toru ENDO)
Determination of pigment combination of ten varieties of the Swiss giant
pansy was made by means of paper chromatography. The results obtained are shown in the table.
Name of Variety
Pure White
Coronation Gold
Giant Orange
Mont Blanc
Rhinegold
Raspberry Rose
Fire Beacon
Alpenglow
Lake of Thurn
Berna

Flavonoid
b
a
-tt
-/-/-

++
-tt
-tt
-tt
-tt
+-

a

Anthocyaninb c d e

-tt
-tt
-ft
-++

-tt
-tt
-tt
-tt
-tt
+-

++-

++-

+

-/-

- (-tt)(+-)- (-tt) (+)-tt - ±
±
+±
-tt
-I-

±

-tt

+-

a

Carotenoid
b c d

-/-

1-

+

+

-/-

+-

+-

+

+-

-I-

-/-

-/-

+-

++

+

e

-/-

--------

The anthocyanins in brackets are those which produce the color of the
blotches.
49

Paper chromatographic analysis of hydrolysed products of anthocyanins
has proved the existence in flowers of all the seven varieties of both cyanidin
and delphinidin. It may be inferred from this analysis that the anthocyanins -a, -c, and -e are glycosides of cyanidin, and -b and -e areglycosides of delphinidin. The Rf values as well as the color of flavonoid- b are exactly similar to those of rutin in all of the four solvents. A
distribution test of crude extracts of carotenoids by petroleum ether andmethanol has succeeded in classifying carotenoid -a, -b and -c as
belonging to the xanthophyll-group, and -d and -e as belonging to the
carotene-group.

K.
1.

IMPROVEMENT OF SOME USEFUL PLANTS

Improvement of Sugar Beets by Means of Induced Triploidy(Reported by Seiji MATSUMURA)

If 2x and 4x beets are planted alternately, 3x seeds can be obtained
through natural pollination either from the 2x or from the 4x plants.
Offspring from 4x mother plants were called, for convenience, 3x-A, while
those from 2x plants were designated as 3x-B. The triploid seeds, however, are inferior to 2x seeds in germination rate. In order to overcome
this difficulty, and to find out the b~st combination, various intervarietal
triploid hybrids were obtained in 1951 and 1952 and examined for germination rate, as well as for other characters.
Table 1 shows the results of experiments conducted on the same scalein two experimental fields of the Japan Beet-Sugar Manufacturing Company in Obihiro and Shibetsll in Hokkaido. In these experiments various
3x seeds, obtained by planting of 4x and 2x beets in the ratio of 3:1, wereused. In the middle of the growth period, plant height and number ofleaves were examined. There was no significant difference in these characters between 3x hybrids and 2x beets (Hon-iku No. 192, the most widelygrown variety), while 3x beets had a decidedly larger girth than 2x in theend of August. At the same time susceptibility of the leaves to diseases
was investigated and denoted by an index. The larger index shows ahigher susceptibility. One triploid combination and its reciprocal, No. 4398
(Hon-iku 398--4x) x 162-A and -B, were most resistant of all, while the
combinations No. 4402 (Hon-iku 402--4x) x 399 and No. 4402 x 48 were mostsusceptible. In yield and sugar content the combination No. 4398 x 162
showed the best results, and this is the most promising combination.
Finally, in the beginning of 1952 this combination was recommended for
promotion as one of the best and called 3n-1 by the Hokkaido Agricultural
Experiment Station and Hokkaido Seed Association. This new combina-

50

tion variety will gradually rep1ace in several years the common varieties
throughout a considerable part of the Hokkaido beet area.
Table l. Comparison of susceptibility to diseases, yield and sugar content
in various 3x hybrids (Mean value of Obihiro and Shibetsu in 1952)-

Susceptibility
index (Rate)

Combination
--

I

--

--

--

,

,.

Hon-iku No. 192
4398 x 162-A
162 x4398-B
4398x 399-A
399 x4398-B
4398 x 401-A
4402x 399-A
4402 x 48-A
48 x4402-B
4048x 399-A
399 x4048-B
4048x 192-A
192 x4048-B
LSD 5%

1.970 (100)1.620 ( 82)
1.510 ( 77)2.390 (121)2.576 (131)
1.981 (101)2.476 (126)3.077 (156)
2.438 (124)2.698 (137)
3.317 (168)
2.772 (141)2.850 (145)
0.713

Yield per Tan* I(Rate)

Sugar %
(Rate)

Sugar content
per Tan* (Rate)

Kin**
5,069 (100)5,948 (117)5,865 (116)5,324 (105)
5,112 (101)4,995 ( 99)
5,115 (101)4,952 ( 98)
5,078 (100)5,050 (100)5,213 (103)5,043 (100)4,613 ( 91)570.2

16.85 (100)16.54 ( 98)
16.40 ( 97)
17.16 (102)16.80 (100)17.55 (104)16.84 (100)
16.92 (100)16.96 (101)16.99 (101)16.62 ( 99)
16.65 ( 99)
16.56 ( 98)
0.733

Kin**
751 (100)
862 (115)
845 (113)806 (107)766 (102)773 (103)780 (104)743 ( 99)765 (102)760 (101)
769 (102)732 ( 98)
675 ( 90)99.4-------* Tan=ca. 0.1 ha,

..

- ~ _

_ - - - _ . - _._-------% Kin=0.6 Kg.

2.

Tetraploidy in Citrus(Report by Kazuo FURUSATO)

Most species of Citrus are diploid, and have 9 gametic chromosomes.
However, during his breeding studies, the author has encountered a few
tetraploid plants with 36 somatic chromosomes.
These tetraploids were of spontaneous origin, artificial stimulation beingout of the question.
In order to make some observations on the conditions and the ways inwhich tetraploids in Citrus arise, a number of seeds of several diploidvarieties (Citrus Unshu, C. natsudaidai and C. Aurantium) were planted
in soil, and, after germination, the seedlings were examined for tetraploids. In each of the three varieties, a few tetraploids occurred, as shownin Table l.
The tetraploids could easily be distinguished from the diploids. Theirleaves were of a darker green, the mesophyll was thicker and the stomata
larger; moreover, the main root was thicker and the number of lateralroots was considerably smaller than in the diploids.

51

Table 1.

Citrus Unshu
C. N atsudaidai
C. Aurantium

No. of plants
examined

No. oftetraploids

Frequency oftetraploids

228

1
3
3

0.4%
0.2%
0.1%

1920

2048

On the other hand, quite like the diploids, they were very uniform, andhad all the features of the mother plant.
It may safely be assumed that they were autotetraploids originatedfrom nucellar cells.
Sometimes, the tetraploids were found in twins; in one case both twin
plants were tetraploid; in another, one was tetra- and the other diploid.
So far, the author has found tetraploids in the following five varities(Table 2). All of them were produced from untreated seeds.
Table 2.
Number of chromosome

Species
---

---

-

36
36
36
36
36

Citr1f,S junos
Ponciru.s trifoliata
Citrus Unshu
Citrus Natsudaidai
Citrus Aurantium

3. Abnormal Growth of Citrus Trees Caused by Deviating
Chromosome Numbers in the Grafting Stocks(Report by Kazuo FURUSA TO)

During an inspection of Citrus groves, the author was shown trees
which, for no obvious reason, were very poorly developed and growing
very slowly. The possible effect of non-genetic factors such as parasites,
management technique or soil condition, has been excluded after athorough investigation. The surrounding specimens were all normal,
healthy and well-grown trees.
The examination of the roots revealed that the lateral roots were very
poorly developed. The investigation of the chromosome number in roottips showed that the grafting stocks of the underdeveloped trees weretetraploid.
In one grove there were as many as 7 such trees among 1000. They
were scarcely 2/3 as high as the surrounding normal trees. Their fruits
were very small and few. Therefore, they meant a considerable loss tothe owners.

52

The differences between the normal and the underdeveloped trees canbe seen from the following table.
Table 3.

Comparison of 15 year old trees grafted on di- and tetraploidstocks in Citrus Unshu.
The branches
The trunk
Number ofof a tree(diameter)
fruits(diametElEt(per year)
d' l"d tetra~-I d' I "dl. tetra·· I. d" i-'d . tetra- d--: I 'd ' tetra- .
_~_~I_ploi~ ~p~~_ ploid~. ploi!.. _~~_i ploidi
2.05m' 1.20m 2.65m 1.53m 9.9cml 4.9cm'187.5 I 40.0.
II
" 49.7
1.46
1.05 i 1.10 I 1.03 , 4.4
. 3.1
9.0
2.30
1.50
2.80
1.72
8.5
4.8
210.0
45.0
1.94
1.25
2.18
1.42
7.6
4.17
149.1
31.3
Plant height.

A section
B section
C section
D sectionI

As to other features of the trees grown on tetraploid stocks, their leaves
were small, curled inward, and of a light green color.
It was interesting to observe that the rind of their small fruits was of a
firm texture in contrast to the loose rind of the normal fruits. The colorof the rind was slightly lighter and the fruits had a normal sugar content.
The firm rind is an advantageous feature wilh regard to storage. The
author is now studying the keeping properties of stored Citrus fruits, andexpects to be able to make some use of the firm rind texture characteristic of those fruits.
From this investigation it has become evident that tetraploid seedlings
occur so frequently in some varieties of Citrus (e.g. Poncirus trifoliata)that they cause serious loss to the owners of groves who use them asgrafting stocks. Fortunately, it is easy to recognize them by their very
thick main roots and by a very poorly developed system of lateral roots,
in selecting plants to serve as grafting stocks.

4. Prospects of Using Triploids in Tobacco Breeding(Report by Kazuo FURUSATO and Akira MIYAZAWA)

Tetraploids have been produced by colchicine treatment in three varieties of tobacco, Bright Yellow, Judy's pride and Xanti. In order to obtain
triploids the tetraploids were pollinated with pollen of the respective diploids.
The plants thus obtained were highly variable in plant height, numberof leaves, and so forth, and their practical utility could hardly be considered.
The lack of uniformity was probably due to irregularities in chromosome
distribution at meiosis of the tetraploids, with the result that in addition
to the expected triploids also a number of aneuploids, Le. hypo- and53

hyper-triploids, have been produced. This was borne out by examinationof the meiotic phenomena.
In the P.M.C. 's uni- and trivalents were observed, in addition to bi- andtetravalents. A similar situation could have been expected in the
E.M.C.'s.
In general, triploids can be produced only when the pollen of the diploids is put on the stigmata of the tetraploids. However, in tobacco,
triploids could be easily produced in both directions of the cross. Moreover, it was observed that the F I was more uniform when a tetraploid
was the pollen provider. The author assumes that this was due to thefact that pollen grains with balanced chromosome sets are more successful in competition.
It is hardly necessary to add, that "triploids" and "tetraploids" intobacco plant are in reality hexaploids and octoploids, respectively.

L.

GENETICS OF MOULDS

1. Appearance of Reversional Mutants in the Methionine-requiring
Strain of Ustilago maydis.
(Report by Tetsuo lINO)

Mass-cultures of a methionine-requiring mutant strain 4-24 of Ustilago
maydis are often found to contain prototrophic cells. Such cells may befound even in the cultures originating from a sporidium which had been
proved to require methionine. This prototrophic characteristic is maintained through successive generations, and the proportion of these cells toth~ requiring cells is increased with the age of the cultures, in spi~e ofthe fact that the growth rates in the complete media are nearly alike.
This phenomenon may be more properly explained by assuming successive
reversional mutations of the requiring cells, than by assuming an increaseof the pre-existing prototrophic cells or some change in physiologicalproperty.
The reversional mutants were screened from the complete sporidia
culture by the following procedure. The culture is centrifuged and washed
3 times in 0.9% NaCI aq. solution. It is then diluted by the minimal
solution, and finally plated on to minimal agar media in petri dishes,and kept at constant 25°C. A dilution of from 5 x 105 to 5 X 106 cells perdish s~ems to be adequate for avoiding indistinction by residual growthand syntrophism.
The spontaneous mutation rate has been calculated from the numbersof the reverted cells at the late logarithmic period after Delbliick's formula
2 (Newcombe 1948). It has been found that the strain undergoes reverse
54

mutation at the rate of 3.0 x 10- 7 per sporidium per division in complete
liquid culture. This frequency may be raised by X-ray (4.5 x 104 r-dose)
irradiation, or by treatment with tris-nitrogen mustard (1/200 mol, pH9.5)
up to the orders of 10- 4 •The growth habit of these reverted mutants has been investigated intWenty clones. Sixteen of these were capable of growing on the minimal
media like the wild type strain. These clones have been named "complete
reversion types (CR)". Four other clones have shown a restricted growthrate on the minimal media, but when supplementary I-methionine wasadded, they grew normally like the wild type. These clones maintained
the restricted growth habits through several subcultures, but within 3 to 8
generations, they acquired the normal growth rate even in the minimal
media. These clones are distinguished from CR, and named "inferior reversion types (lR)". The restricted growth of the IR is not due to the
mixture of the original mutant and CR. This is demonstrated by the
unimodal distribution of the colony size after plating IR to the minimal
media. The cause of the inferior reversion may be explained by assuming
the following alternatives : either a sort of suppressor mutation or phenomic lag. At present it is hard to decide whether the present IR type is dueto the first or the second alternative. This will be clarified in the future.

2.

Studies on Heterocaryosis in Aspergillus and Penicillium.
(Report by Seiz6 TSUDA)

The author (1951) found a spontaneous heterocaryon which occurred
frequently in the stock culture of Aspergillus candidus, and he has carriedout morphological and cytogenetical investigations on this strain.
The author has succeeded in inducing heterocaryon formation between
two varieties of Aspergillus Awamori and between two mutants of Peni·
cillium chrysogenum TROM. Q176 strain. The culture medium was synthetic CZAPEK-DoK agar medium.
The heterocaryon formed by the 5-9 and the N-19 varieties of Aspergillus Awamori was intermediate in character between the two parental
varieties, so far as the color and the form of colony were concerned.
The heterocaryon in Penicillium chrysogenum was formed between two
mutants induced by ultra-violet irradiation. One of these, UY-3S, forms
a jagged colony and produces a large amount of yellow-colored substancewhich is sorbicilIin and penicillinic acid. The other strain, UW-lS, forms
a round and colorless colony. The spores are whitish in both strains andhardly distinguishable. The conidia of the heterocaryon formed between
these mutants are green, and contain yellow substance, just as in the wild
type of Penicillium chrysogenum TROM. Q176.
The presence of the colored substance and the jaggedness of the outline55

of the colony in the former strain are closely correlated, and this is also
true of the correlation between the colorlessness and the smoothness of thelatter strain. The heterocaryon is highly variable in the color and outlineof the colony. The number of nuclei in each cell of Penicillium is usuallymore than 12, and it is more than probable that the high variability in thecharacters of the heterocaryon is largely due to variety in the combinations of the two parental nuclei.

M.
1.

STUDIES ON COMPETITION

Competition between diploid and autotetraploid plants of barley.
(Report by Kan-Ichi SAKAI and Yasuo SUZUKI)

Diploid and autotetraploid plants of each of two barley varieties werecompared for their competitive ability. Seven plants were planted in agroup so that six of them surround one plant which was to be tested withrespect to its competitive ability. The spacing between any two plants
was 23 ems. The design of the experiment was the split plot one withfive replications in one variety and six in the other. Data have been taken
for plant weight, number of culms, number and weight of heads, number
and weight of seeds and sterility percentage of spikelets on an individual
plant basis. Analysis of variance of the data obtained has been conducted.

Character

Variety

Mean values of seven characters of diploid vs.
tetraploid plants in pure stands andin mixtures. Diploid su~rounded b Y Te~iap~oid s\lr!"olmdedb-,YiI

Hosogara-No. 2

I

I

tetraploids I

d~~IOid~! te~raploids

Sterility

33.1
11.8
11.6
13.7
11.0
196.6
9.3

GO.6
IG.6
IG.G
20.1
16.1
Z70.4
7.2

23.7
6.8
6.7
8.6
6.1
91.7
29.7

10.0
3.9
3.8
3.4
2.4
3G.l
36.6

Plant weight
Number of culms
Number of heads I
Weight of heads
Weight of seeds I
Number of seeds i

37.0
9.4
9.4
17.4
14.2
G30.4

G7.0
14.0
13.8
26.3
20.8
826.4

31.8
7.4
7.0
12.9
8.0
2G1.0

11.G
3.G
2.6
4.0
2.6
83.4

Plant weight
Number of culms
Number of heads
Weight of heads
Weight of seeds
Number of seeds

Golden Melon

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

56

The mean values of each quantitative character of the diploid and tetraploid plants affected by competition, as contrasted with those of purestands, are presented in the table above.
As shown in the table, the diploid plants were always better competitors than the tetraploid plants of the same variety in both varieties. The
diploid plant surrounded by six tetraploid plants of the same variety has
gained 33-56 percent increment in the characters as compared with thosein the pure stand. The sterility percentage of spikelets of tetraploid
plants was distinctly increased by the surrounding effect of the diploids.
It may be concluded accordingly that the autotetraploid plants of thebarley varieties are considerably handicapped by severe competition with
diploid plants, if they are among a population of the parental diploids, atleast under such circumstances as in the present experiments. Thus it
seems certain that a few autotetraploid plants spontaneously arisen in a
diploid barley population have but smaIl chance to supplant the parental
diploids by competition with the latter, unless some change in environmental conditions takes place.
2.

Competition between an Artificially Synthesized Amphidiploidand its Ancestral Species of Abelmoschus.
(Report by Kan-Ichi SAKAI and Yasuo SUZUKI)

Abelmoschus glutino-textilis (2n = 192) is an artificial amphidiploid
species between A. esculentus (2n= 124) and A. Manihot (2n=68), originally synthesized by Prof. F. Kagawa in Kyoto University. We have madean experimental study on the relative competitive ability of the originaland synthesized species. The experiment was conducted by the split-plot
design with four replications. The planting of individuals was madehexagonally, so that six plants surround one plant which was to be tested
with respect to its competitive ability. The spacing between any two of
the plants was 24 cms. The characters examined were plant weight, plantheight, number and weight of fruits and number and weight of seeds onan individual plant basis. Statistical tests of the data obtained were conducted by analysis of variance.
The mean values of all six characters of the three species in both purestands and mixtures are presented in the table.
Inspection of the mean values of the character3 in the table leads one
to conclude that the amphidiploid Abelmoschus glutino-textilis is the bestcompetitor and that one of the parental species A. Manihot is the worst
competitor of the three species examined.
AIl the characters, except plant height, of A. glutino-textilis in the mixture with A- Manihot, reached twice or even more than three times asmuch as those in pure stands. Even with A. esculentus, the increment of57

·'·~-~I· AVe~ge val~es of plant weight, plant. height, number andI

Characterweight of fruits and number and w:ellitht of seeds on an
individual plant baSIS 111:.. --.------- - - -....- - - - - - ,- - - - - - - - - -IIManihot surrOUnded.i

esculentus sur-I

glut'ino-temilis

I~*Tb~~ g*_t~*~o~n~ ~y ~*1~:7~~_iPlant Weight(g)-r 55.3-\ 21.8 : 14.6: 154.3 320.5 ! 63.71150.3\332.51274.7
Plant height(cm)43.5' 34.2 29.7' 107.6 I 92.7 • 97.9 161.4, 165.6 166.0
Number of fruits I 3.5
1.2, 0.7
2.7
4.9' 1.1
3.1 I 7.1
5.9
Weight of fruits(g)!
3.9
1.4 i 1.1
18.7 38.5 I 6.9
6.1' 20.8:1 18.3
Number of seeds
107.9 27.0 25.9 199.4! 382.9 I 57.8 42.4 i 148.4 126.8
1Weight of seeds (g) I

2.3

0.4

~_ 12.7 ~~~.4 i·l '7.~_~_

2.1,--,;;- M: e a;:~g-~tand-f~r Abelmoschus Manihot, A. esculentus and A. glutinotextilis respectively.

A. glutino-textilis gained in the mixture was distinctly large.
From the results described above, it may be concluded that the amphidiploid species is a good competitor against both its parental species so far
as the present plant species and the conditions of the present experimentare concerned.
3. Intervarietal Difference in Competitive Ability in Hordeum sativum L.
and Oryza sativa L.
(Report by Kan-Ichi SAKAI and Kanji GOTOH)

In this experiment the competitive abilities of twelve varieties of barley
were compared, as well as those of five varieties of rice-plants.
(1) Hordeum sativum L.
Twelve varieties of barley in pure stands and in mixtures of all possiblecombinations of two varieties in each were planted according to a simple
lattice design with four replications. The characters examined were thenumber of culms and the weight of grains per plant. Analysis of varianceof the data obtained has proved that the variation among varieties in purestands as well as in mixtures was statistically significant. Further analysis
of variance was conducted on the increment or decrement of characterswhich was solely due to competition between different varieties. This
analysis has proved that the varieties differed significantly in their competitive ability. These analyses have enabled the writers to rank according to competitive ability, the twelve varieties of barley into grades fromthe lowest to the highest, taking the number of culms and weight ofgrains as indicators of the ability. The rankings in regard to the two
characters are in fair agreement with each other.
58

Oryza sativa L.
In 1951, six varieties of rice plant, Oryza sativa L. were examined fortheir competitive ability (cf. 195] issue of this Report). Further studies
were attempted on five other varieties by using the three of the six varieties of the 1951 experiment, as testers. Experiments were conducted by
the split-plot method, with three replications. Analysis of the variances inplant height, plant weight, as well as in the number of panicles has revealed that the varieties differed significantly for all of the four characters,
but that the variation due to the competitive effect was significant only at
the 5 percent level of probability as to, plant weight and weight of panicles, while it was almost significant with respect to the number of panicles.
Comparison of the mean values of increment or decrement in the fivevarieties has enabled the writers to classify them according to their competitive ability.
We seem to be justified for the present to conclude from the two experiments described above, as well as the one already reported, that varieties
within one and the same species may significantly differ with respect totheir competitive ability.
(2)4.

Competition between the Upland-Rice Plant and the" Red-Rice" Plant.
(Report by Kan-Ichi SAKAI and Yasuo SUZUKI)

It is known that the so-called "red rice" often contaminates a population of upland rice and spoils the crop. " Red-rice" is one of the primitive varieties of rice belonging to the subspecies Indica of Oryza sativa L.
Our interest has been directed to finding out if the red rice has any selective advantage in a mixed population with the commercial rice plants.
This is the first report dealing with the relative competitive ability between
the red-rice variety and the commercial variety of upland-rice.
Young plants of the Norin No. 21 variety of upland rice, and those of
red rice grown from seeds obtained in Saitama-ken, were individuallyplanted in the plots. The planting was made in such a manner that agroup of seven plants form a regular hexagon with one plant in the center.
Arrangement of the experimental plots was made according to the splitplot design with three replications.
The characters examined were the height and weight of plants, thenumber and weight of panicles, and the weight and number of grains on
an individual plant basis. The analysis of the data thus obtained has
proved that the variation due to interaction between competition andvariety was highly significant. The mean values of each character inevery treatment in the experiment may be seen in the following table.

59

Upland rice
Number of surrounders I
of another variety
Plant height (em)Plant weight (g)Number of panicles
Weight of panicles (g)Weight of grains (g)Number of grains

03

Red rice

682.3 79.9 73.2
13.4 10.3
8.2
3.84 2.53 2.38
6.33 4.45 3.08
5.60 3.90 2.78
231.1 139.5 94.7

0

3

6

83.8 82.6
9.5
9.4
4.11
5.05 5.25
3.10 4.38 4.67
2.67 3.76 4.26
145.5 215.1 213.8
75.8
7.2

-Standard
I error

3.32
0.97
0.45
0.59
0.66
35.7

It is apparent from the table that the upland-rice plant surrounded by
red-rice plants suffered considerable decreases for all the characters examined, and the reverse is true for the case of the red-rice plant surrounded by the upland-rice plants. It is concluded from this finding thatthe red-rice variety is a good competitor against the upland-rice variety,and it is possible that a few plants of the red rice mingled in a populationof the upland rice will propagate at an extraordinary rate, so far as thecompetition is concerned.

N.
1.

THEORETICAL GENETICS

Theoretical Considerations on Random Drift of Allelic Genes or
Chromosomes and Decrease of Heterotic Vigor
in Allogamous Plants.
(Report by Kan-Ichi SAKAI and Yasuo SUZUKI)

Concerning the production of original seeds of allogamous plants,
especially of root and leaf crops, there are some problems which are ofinterest from the viewpoint of population genetics. The problem dealt
with in this paper is that which concerns the possible degeneration of an
improved variety of these crops due to selection of, and propagation from,a very small number of elite plants for many generations for seed growing. Such a procedure is customary among seedsmen in Japan. The
elite plants are chosen primarily with reference to morphological characteristics of the crop only.
Let us consider a panmictic plant population with an allelic pair of genes
or of chromosomes causing heterosis for a given character in the heterozygotic condition. The heterosis may concern either some productive property or resistance against some deleterious effect, but on account of its
quantitative nature, it may not become an object of selection. Let a pairof genes or chromosomes be A and a with frequency p and q respectively

60(P+q=l). If we take N individuals at random from the population, 2N
of A and a will be included in a small population of N individuals. The
probability of the small population to have a with the frequency qi will begiven by
(2N) !
p 3N1J 3Nq(2Nqi)!(2NPi)!1 q i.
The small population thus obtained will be propagated, and selection of
N elite plants from the increased population will again be carried out.
This process will be repeated year after year. After n times replicationof such a propagation and selection, a population involving a in the frequency qn will be found with the probability given below:
2N 2N

2N

'l.N 'l.N

2N

i-O j=om=O2: 2:····2:CNC2NqiP3NPi q3NQ'I)(2NC2Nqj PiNPj q7NQj)····(2NC2NQnP~Pnq~Qn).
This process of repeated propagation and selection of elite plants accordingly will ensue random drift of allelic genes or chromosomes. As a result
Number of mother plants selected

2
0

;::
Q,l

>

3

5

7

10

15

0

0

0

0

0

0

0.50

0.50

0.50

0.50

0.50

0 . .50
0.48

1

12.50

3.13

0.20

0.01

0.38

0.42

0.45

0.46

0.48

2

33.20

14.56

2.78

0.52

0.04

0.28

0.3.5

0.41

0.43

0.46

..... ;::'

3

49.79

27.48

8.28

2.47

0.41

0.02

0.21

0.29

0.36

0.40

0.43

0.45

,<::..0<'>r:JJ.

4

62.33

39.20

15.24

5.88

1.42

0.11

0.16

0.24

0.33

0.37

0.41

0.44

5

71.75

49.23

22.59

10.28

3.16

0.43

0.12

0.20

0.30

0.35

0.39

0.43

6

78.81

57.66

29.77

15.21

5.55

0.60

0.09

0.17

0.27

0.32

0.37

0.41

7

84.11

64.71

36.50

20.33

8.43

1.53

0.07

0.14

0.24

0.30

0.35

0.40

8

88.08

70.59

42.71

25.44

11.65

2.76

0.05

0.12

0.22

0.28

0.33

0.39

9

91.06

75.49

<18.37

30.40

15.07

4.27

0.04

0.10

0.19

0.26

0.32

0.37

93.30

79.58

53.50

35.14

18.60

6.00

0.08

0.08

0.17

0.24

0.8D

0.36

.So",
d~
,<::al<.>.~Q,l,<::r:JJ.

~!llI

o'iiJ

~~

;::~

.~

0..

r:JJ." ...
;::Q,l

.S:S

""0

~S
Q,l
;::

....

Q,lO

!llI ...

.... $

OsaJ::l..0;::

S
::l
Z

10

0.47

* The Roman type numerals represent the probability of losing one memberof the pair of allelic genes or chromosomes, and the italicized numerals, theaverage magnitude of heterotic vigor.
61

of such random drift, the average heterotic vigor in the population will
decrease gradually.
Now let p and q of the initial population both be equal to 0.5, andassume that 2, 3, 5, 7, 10 or 15 elite plants are selected for various characteristics, other than the heterotic vigor in question, in each generation.
Thus, the probability of losing one of the allelic genes or chromosomes,that is, the probability of becoming homozygous with respect to the allele,
and the intensity of heterotic vigor have been computed for ten generations of propagation and selection of mother plants, and the values thus
obtained are presented in the accompanying table. The heterotic vigor inthis case has been assumed as 0 in AA or aa homozygotes and 1 in Aa
heterozygotes.
The numerical values presented in the table may offer a warning against
the present status of the small-scale seed growing in this country.
2.

"Stepping-Stone" Model of Population.
(Report by Motoo KIMURA)

It is recognized by many recent investigators that population structureis one of the most important factors in speciation. For theoretical studies
on the problem of speciation, models of population structure are used.
Wright has designed two different models, namely, the island model andthe model of continuous distribution (d. Ann. Eugen. 15, 1951). In thepresent the report writer proposes a new model of population structure
which may be called the "stepping-stone" model.
In this model, a whole population is subdivided into many local subgroups
within each of which mating occurs at random and exchange of individuals
between the groups is allowed to occur only between adjacent ones. This
may represent an intermediate situation between those of the two contrasting models stated above. Fig. 1 and Fig. 2. show respectively cases oflinear and area distribution. Contrary to the case~-~of the island model, there exists a high correlation
between adjacent subgroups in the stepping-stoneFig. 1model, so that a considerable amount of random
differentiation of gene frequencies may be expectedamong the subgroups even if the rate of migration
is appreciably high. The following is a result
obtained by the study on the linear distribution.
If the number of breeding individuals in eachsubgroup is N and the net rate of exchange of individuals between two adjacent subgroups is e, thenthe distribution curve of gene frequency (X) among
Fig. 2the subgroups will be given by~-62¢(X) = CX8NeC1- r )X-l(l_ X)8NeCl-r)(1-X)-I ,where X is a mean gene frequency in the whole population, and C is aconstant chosen such that )~¢(X)dX= 1.

In this formula r represents acorrelation coefficient between the gene frequencies of two adjacent subgroups and is a positive root of the quadratic equation;
er2 +(2-3e)r+(4e-2)=0.
Therefore if e is small, r is approximately equal to I-e.
In this case the variance of gene frequencies among subgroups becomes
V =X(I-X)/[1 +2Ne 2(4+ e)].
2
If 8Ne (I-X) and 8Ne 2 X are smaller than 1, a considerable amount oflocal differentiation due to random fixation of alleles will be expected.
Since 2N e is the number of immigrants coming from adjacent subgroups
per generation, if X = 0.5, such conspicuous differentiation may be expected unless this number does not exceed viN. For example, if the size ofthe subgroup is 10,000, such a situation will be realized unless the numberof the migrants is less than 100. On the other hand, in the island model
the number of immigrants should be less than {-, for the corresponding
amount of differentiation to be realized.
In the stepping-stone model, if the long range dispersal of gametes istaken into consideration, it comprises the island model as a special case.
Thus under certain circumstances the stepping-stone model may reflect thestructure of a natural population more fully than the island model or themodel of continuous distribution.

3. Process leading to Quasi-Fixation of Alleles due to Random
Fluctuation of Selective Values.
(Report by Motoo KIMURA)

Since the pioneering works of Fisher and Wright, a considerable numberof mathematical studies have been performed concerning the "genetic
drift" which is brought about by random sampling of gametes in a finite
population. Its genetical implications have also been discussed extensively.
On the contrary, little has been worked out on the process of change ingene frequency controlled by the random fluctuation of selection intensities. In his brief account in the annual report of this institute (1952), thepresent writer has shown by using an approximate method of transformation that this process can be looked upon as a sort of deformed Gauss
process. Recently, he has succeeded in solving completely this problem
for the simplest case.
Let A and A' be a pair of alleles which are neutral on the average andlacking dominance. If the population is indefinitely large, the relative pro63

bability ¢(x, t) that the frequency of gene A will be x~x+dx in the t-th
generation satisfies the following Fokker-Planck equation:( 1)

8¢(x, t) = V. 8~{ 2(1- )'¢( t)}8t
2 8x2 xX
x,,where V. is the variance of the selection coefficient of gene A.
If the initial frequency of gene A in the population is xo, the solution of(1), satisfying the boundary condition; ¢(O, t)= ¢(1, t)=O, is
1 x(l-xo)J2_
1{v.t [ og (f-;)~ } [xo(l- xo)]1/2(2) ¢(x, t)- v'2nVst exp -~8---2V.t- . tx(I-=-~jj:iG (t>0).
When xo=0.5 the distribution curve given by (2) is unimodal when t issmaller than4
3Vs
but becomes bimodal if the value of t exceed this amount. Therefore
when t becomes very large, the curve will assume a U shape.
n may be important to investigate the process of change in terminal
distributions after a sufficient number of generations has elapsed. Let us
consider the terminal region of distribution, where the frequency of thegene A is very low. If Xmax is a gene frequency giving a maximum value(¢max) of the distribution curve, then
(3)

Xo

-+Vst

Xmax~--el - xo

0

-

and
~

(1- x o)2 V.t _co,
Xo e
as t becomes indefinitely large. Under such circumstances special attention must be paid to the following relations;- Let e be any assigned
gene frequency, no matter how low, if we take the number of generations(t) as sufficiently large so that
I log a IIVs ,then the probability that the frequency of the gene A in the population islower than e approaches l-xo. Symbolically;
( 4)

A.

'l'max.1.

v' 2n V.t

t>-

(5)

Pr{O<x<e}~(I-xo)-O(~-~_v.t)v'V.t(t --> co).

Nevertheless, the probability that it is lower than Xmax approaches 0,(6)P,{O<X<Xmax}~O( e-}- V.t)
2..

v'Vst

..

(t --> co).

Similar relations hold for another terminal region where the frequency ofgene A very high. As will be seen from the relation;
limI1-¢(x, t) dx=1 ,

NOJ.

64

this process cannot lead to the complete fixation or loss of alleles as in thecase of the drift. But as is shown in the above formulae, (3)-(6), theclass frequencies shift toward either terminus indefinitely with time. So
after sufficient numbers of generations, a situation is to be realized inwhich an allele is almost fixed in the population or almost completely lostfrom it. To distinguish this from the fixation or loss in the case of thedrift, the terms quasi-fixation or -loss may be proposed. In practice, thisprocess will finally be checked by the opposing mutation pressures.

4.

On Simultaneous Distributian of Gene Frequencies in Populations.
(Report by Motoo KIMURA)

Any attempt to obtain a comprehensive formula for the simultaneous
distribution of gene frequencies in populations may encounter serious
mathematical difficulties, when one assumes the existence of random
fluctuations in selective values. Wright's formula for the simultaneous
distribution of gene frequencies apparently does not give an answer to thisproblem.
For solving the problem, extension of the Fokkar-Planck equation to a
multi-variate case may be useful.
Let Xi (i=l, 2, .... , n) be the gene frequency in the i-th locus. It canbe shown that the relative probability, ¢ (Xl> X2, •••• , X n ; t), concerning thesimultaneous distribution of gene frequencies for the n loci in the t-th
generation satisfies the following partial differential equation:8¢
1 n 8282n8(l)8t =~2-- -2: 8-----:; (Vsx!¢) + 2: (WSXtSXj ¢) - 2'>8--(MsXi ¢) ,
i~I

Xi"

i>j 8Xi 8Xj

i-I

Xi

where OXi is the rate of change of gene frequency (Xi) per generation for
the i-th locus, Ms xi and Vsx; are respectively the mean and the varianceof Xi, and W SXtSXj is the covariance between OXi and OXj. The distribution at the stationary state may be obtained by putting~~ =0.

A special example for n=2 will
Table 1
Table 2
be given here. Consider a very I~~~--------- ~- I
Ilarge random breeding population
Genotype S~~l~~ve I Mutation Rate I
V -I - of a haplont species, and assume
AB--1A----uIthat selection operates only in ha,~Iplophase. We may put selective
Ab
11
Iii
::
values and mutation rates as inaBI
B::;::=: b
Tables 1 and 2, where A, a and
ab
l~~_J
~
I
B, b are two pairs of alleles.
If we write the frequencies of a and b respectively as X and y, then (1)becomes

r---

!

L

65

(2)

[)if>
V [)2
[)2
_=_k ~~{y2x2(1-x)2if>J+V k[x 2(1-x)y2(1-y)if>]
fit
2 ax~
[)xay
+ V k a:' [x~'y2(1-y)2if>]- a [(kyx(1-x)-ulx+v1(1-x»if>l
2 ay'
ax
[)

-

-ay-[(kxy (1-y)-u 2y+ v 2(1-y»if>],where Ii and V k are respectively the mean and the variance of the selection coefficient k. If mutations are non-recurrent and the ab genotype isselectively neutral on the average (k=O), the distribution at the stationary
state satisfies the following partial differential equation of parabolic
type;[)2a2[)2.
[)x2[xY(1-x)2if>]+2aXay [x Y (1-x)(1-y)</>]+8 2[xY (l-y)2</>J=O ,ywhich has a general solution;

F('-c<)+G(t:;)

if>(x,y)= _}-L.. 1-x __x 2y2(1-x)(1-y)

In this formula F(r;) and G(r;) are two arbitrary functions of r;.

.'

66

BOOKS WRITTEN BY THE MEMBERS OF THE STAFF
KOMAr, Taku. 1952. Genetics with Special Reference to Man. pp. 230. BaifU-kan,
Tokyo.
et aI. Genetics of Drosophila and Guide to Experiments. pp. 205. Ibid.
MATSUMURA, Seiji. 1952. Studies on the Pentaploid Wheat. pp. 197. Hokuryilkan, Tokyo.
SAKAI, Kan-Ichi. 1952. Science of Plant Breeding. pp. 342. Asakura Shoten, Tokyo.
TAKEN AKA, YO. 1952. The Determination and Inheritance of Sex. (Handbook of
Biology: Cytology, Genetics and Evolution) pp. 130-157. Nakayama Shoten,
Tokyo.
TANAKA, Yoshimaro et aI. 1952. Genetics of Silkworm. pp. 576. ShokabO, Tokyo.
TSUJITA, Mitsuo. 1952. Morphology and Embryology of Silkworm. (in Tanaka
et a!': Genetics of Silkworm) pp. 75. Shokabo, Tokyo.

PAPERS WRITTEN BY THE MEMBERS OF THE STAFF
END,O, T. 1952. Paper-chromatographic analysis of flower colors in Viola tricolor.
Jap. Jour. Genet. 27: 201.
FURUSATO, K. 1952. Studies on polyploid watermelon. (Preliminary report).
Seiken Ziho 5: 125-128.
1952. The tetraploid watermelon, "Kaho," raised by the colchicine
method. Seiken Ziho 5: 131-132.
- - - 1952. Investigation of flowering of sugar cane at Saipan island. Ibid.
5: 133-134.
~-- 1952. Studies on polyploid in. Citrus. (Abstract) Jap. Jour. Genet.
27: 206.
1952. Studies on the tetraploid stocks in Citrus and watermelon. (Abstract) Jap. Jour. Breed. Supp!. No.2: 1.
- - - - and MIYAZAWA, A. 1952. Report on pollination of triploid watermelon
with pollen of various diploid varieties. Seiken Ziho 5: 128-130.
- - - and TANAKA, M. 1952. Studiei'\ on artificially induced polyploid "Makuwa"(Cucumis Melo L. var. Makuwa Makino). 1. Tetraploid" Makuwa" inducedby colchicine method. Ibid. 5: 100-105.
GOTOH, K. 1952. Studies on the heterosis in egg-plants. (Preliminary report)(Abstract) Jap. Jour. Breed. 1: 196.
1952. The heritability of some quantitative characters and dominancerelation of their genes in egg-plant. (Abstract) Jap. Jour. Genet. 27: 205.
1952. The effect of selection in plant breeding (general review) 27: 1205
-1209.
1952. The quantitative characters and the genes controlling them. The"Iden", 6: 6-9.
IINO, T. 1952. Reversional mutations in the methionine-requiring strain of
Ustilago maydis. Jap. Jour. Genet. 27: 79-84.
-- - - 1952. Studies on the biochemical mutants of Ustilago, II. Amylase
Active mutant. (Abstract) Ibid. 27: 209.
KIMURA, M. 1952. The role of crossing-over in the process of introgressive67hybridization. (Abstract) Ibid. 27: 226.
--- and ONO, H. 1952. Left- and Right-handedness of spikes and its transmitting system in the genus T1·iticum. (Abstract) Ibid. 27: 204.
KOMAI, T. 1952. Semi-allelic genes. Pap. Coord. Res. Genet. III: 111-116.
1952. Population genetics in man. (Abstract) Jap. Jour. Genet. 27: 197200.
1952. Incidence of the genes for coat colors in Japanese cats. Annot.
Zool. Japan 25: 209-211.
1952. On the origin of the tortoiseshell male cat-a correction. Proc.
Jap. Acad. 28: 150--155.
-----~, KISHIMOTO, K. and OZAKI, Y. 1952. Genetics of human microcephaly.
(Abstract) Jap. Jour. Genet. 27: 229.
MATSUMURA, S. 1952. Chromosome analysis of the Dinkel genome in the offspring of a pentaploid wheat hybrid. I. Nullisomics deficient for a pair ofD-chromosomes. Cytologia 16: 265-287.
1952. Idem. II. Which of the three vulgare genomes of the ~-speltoid
is incomplete? Ibid. 16: 307-314.
-~ 1952. Idem. III. 29-chromosome D-haplosomics and their relations tonullisomics. Ibid. 17: 35-49.
- - - - and MOCHIZUKI, A. 1952. Comparative studies on triploid sugar beets.
(Abstract) Jap. Jour. Breed. 2, Suppl. No.1: 7.
- and FUJII, T. 1952. Experiment with ultra short-waves in Einkorn
wheat. (Abstract) Jap. Jour. Genet. 27: 210.
SAKAGUCHI, B. 1952. Experimental and embryological studies on silkworm bymeans of high-speed centrifuge. (Preliminary report) J. Seric. Sci. Japan
21: 74-83.
-~-- 1952. Experimental and embryological studies on Eri-silkworm by meansof centrifuge. (Abstract) Ibid. 21: 74-83.
SAKAI, K. 1952. On the effectiveness of mass-selection and the method of preservation of the hybrid-bulk in the bulk-method of plant breeding. Agr.
and Hort. 27: 5-8.
1952. The competition among yarieties in rice plants. (Abstract) Jap.
Jour. Breed. 2, Suppl. No.1: 2.
- - - and GOTOH, K. 1952. Inter-varietal differences of competitive ability
in barley. (Abstract) Jap. Jour. Breed. 2, Suppl. No.2: G.
- - - - and SUZUKI, Y. 1952. Random drift of allelic genes and decrease ofheterosis in propagated seeds of allogamrms plants. (Abstract) Jap. Jour.
Genet. 27: 206.
- - - and - - - - - 1952. Experimental studies on the competition between
the diploid and the tetraploid races in barley. (Abstract) Jap. Jour. Genet.
27: 207.
TAKENAKA, Y. 1952. Karyotypes and sterility in Hemerocallis Pap. Coord.
Comm. Res. Genet. III: 71-90.
- - - - 1952. Cytogenetics of Nicotiana, I. Reduction divisions of some hybrids. (Abstract) Jap. Jour. Genet. 27: 211.
TANAKA, Y. 1952. Further studies on the dominant" retarded" silkworm strain
obtained by X-ray treatment. (Abstract) Jap. Jour. Breed. 2, Suppl. No.
1: 10.
68

1952. Mutual relation between" multistars," "multilunar" and" knobbed." Bull. Seric. Sci. Japan 21: 160.
- - - 1952. Different stability of various types of the multilunar pattern ofBombyx. (Abstract) Jap. Jour. Genet. 27: 230-23l.
TUTIKAWA, K. 1952. The inheritance and expression of the apparently newgene" alopecia periodica" in the mouse. (Abstract) Jap. Jour. Genet. 27: 226.
TSUDA, S. 1952. Sexual reproduction in bacteria. The "Iden" 6(10):45-47.
1952. On a few cases of heterocaryon in Aspergillus and Penicillium.
(Abstract) Jap. Jour. Genet. 27: 228.
TSUJITA, M. 1952. Studies on the so-called multi-allelic series in the silkworm:
On the relation of Ell to EKP. (Abstract) Jap. Jour. Gent. 27:231-232.
1952. Comparative studies of the virus infecting silkworm and the virus
infecting Drosophila. (Abstract) J. Seric. Sci. Japan 21: 154-155.
1952. Studies on the E-series in silkworm-the individual with the
genotype of Ell EKP / + +. (Abstract) Ibid. 21: 155.
~--~ 1952. Bacterial viruses investigated from the viewpoint of genetics. The"Iden" 6(12) : 46-47, 7(1): 45-47, 7(2): 41-43.
- - - and SAKAGUCHI, B. 1952. Biochemical and genetical studies of thelethal lemon larva in the silkworm. (Abstract) Jap. Jour. Genet. 27: 218.
YOSIDA, T. H. 1952. Cytological studies on cancer, V. Heteroplastic transplantations of the Yoshida sarcoma, with special regard to the behaviour of tumor
cells. Gann. 43: 35-43.
1952. Idem. VI. Spontaneous tumors occurring in inbred mice, with
notes on establishment of two new strains of transplantable tumor. Jour.
Fac. Sci. Hokkaido Univ. Ser. VI. Zoo1. 11: 41-50.
1952. A histological study on the spontaneous tumors occurring in
inbred mice, with remarks on two new strains of the transplantable tumor.
Gann. 43: 417-418.
1952. Chromosomes studies in the Coleoptera, V. A study of thechromosomes in 12 species belonging to the Carabidae, Cerambycidae, Chrysomelidae, Coccinellidae and Silphidae, with remarks on the balanced condition
between the autosomes and sex-chromosomes. Pap. Coord. Comm. Res. Genet.
III: 41-49.
1952. Behavior of tumor cells of the Yoshida sarcoma in the heteroplastic transplantation. Idem. III: 185-198.
1952. Cytological studies on the effect of colchicine and nitrogenmustard upon turmor cells of the Yoshida sarcoma. Idem. III: 199-204.
1952. Karyotypes of tumor cells of the Takeda sarcoma. Medicine
and Biology. 25: 192-195.
- - - - 1952. Chromosomes in cancerous cells of mice. (Abstract) Jap. Jour.
Genet. 27: 223.

69

,t

•

I
I
II

1!B;fIl 28 ~ 9 JI 30 B !=iJIilU
1!B;fIl 28 ~ 10 JJ 5 B, 9Eff 'iilm1f

/1"

1m

=
* •

·--1
f~

.1l11/iiJ ~ Ph m~!II 1, 111
i ~fTm IE j'[ iI: ~ ~ litf ~ JiHI
JlfJA'fi&9'"fI\; III g 'M ±~ PIJl (l)10. I FPIilU1f ~~J10KmTf{;!Ilg'M±~PIJl(l)10 I
I FPMJUm :~ OO~3t~I=IJ1Jjjtl1tr± II~~[~ ~~-~~""Mt.Huzil~i)'\<,;;; .. "'::"1111"",.. ~~#··i.:;ii8i@l~IIII\I,"~

\

o!

100

200

400
t

600
t

800

1000m
!