Flower buds of sesame plant (Sesamum indicum L.) were internally subjected to β-rays from absorbed radiophosphorus (P³²) by using three different methods, stem injection, radicle immersion and leaf immersion.
The applied radioactivity ranged from 0.005 to 1.5μc per ml. at the start of experiment.
The effects of β-rays emitted from P³² on living cells were measured by observations on the meiotic chromosome aberrations of the treated plants, and aberration frequency obtained proved to be proportional to dosage of β-rays.
Aberrations at MI, chromosome chains, rings and frying-pans were more frequently observed, and those at AI laggard chromosomes or acentric fragments were commonly seen throughout the treatment. Among β-ray effects were fragmentation, bridge, stickiness, formation of multipolar spindles and others.
Cells in tetrad stage, or pollen grains from treated plants exhibited many abnormalities in size, shape and number.

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Heritabilities and genetic correlations in some economically important characters were estimated and an attempt was made to construct an index which could be used under our farm conditions in Japan.
Heritabilities of rates of egg production were estimated to be 0.31, 0.17 and 0.15 for winter rate (P₁), spring rate (P₂) and total rate (P₃) respectively, They were also estimated to be 0.48, 0.43, 0.46 and 0.49 for sexual maturity (S), body weight at sexual maturity (W₁), body weight at approximately 300 days of age (W₂) and egg weight at sexual maturity (EW), respectively.
Genetic correlations between P₁ and P₂, P₁ and P₃, and P₂ and P₃, were 0.187, 0.638 aed 0.701 respectively for production characters. They were estimated to be -0.210, 0.003 and 0.173 for SP₁, SW₂ and P₁W₂, respectively.
An index which could be applied under our farming conditions was proposed as follows:
I=1.40X₂-X₁+25.873X₃
Where the subscripts 1 to 3 refer to sexual maturity, winter rate and body weight at 300 days. The economic weights assigned to the above three characters were -2, 5 and -1 respectively. The index is correlated 0.705 with the aggregate genotypic value of the birds.
Expected genetic changes in the means of the population selected on different criteria of selection were compared. It is evident that the efficiency of selection based on the index would be greater than selecting for any one of the characters involved in this study.

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The present paper reports some genetical data on transplantability of the MY-mouse sarcoma. This is a kind of the spindle cell sarcomas, which developed in a So-strain mouse. The mice have not yet been established as a pure inbred strain. It has been shown that the transplantability of this tumor shows a considerable difference according to the strain of the host tried (Table 1). In the transplantation experiments, it was found that the mice of D- and S-strains showed a high transplantability. Through selection these mice were separated into two strains; D-103 from D strain and S-4 from S strain. They showed a very high transplantability, giving 92.15% and 100% transplantability for D-103 and S-4, respectively, whilst C3H, A, DBA/2, SWR, Swiss albino and CBA strain mice were all negative in transplantability of this tumor. The transplantability Was observed in F₁ hybrids between two starins, D-103 C3H, and a successful results were obtained in every test. From this result, it is presumed that the transplantability of this tumor was controlled by some dominant genes (H-genes). In order to observe the number of these genes, the transplantability was examined in F₂ hybrids and back crosses, C3H×F₁: 57.3 percent of F₂ and 30.7 percent of RF₁ hybrids showed a positive transplantability. Based on the above results, it is most probable that about two dominant H-genes are concerned with the transplantability of this sarcoma.
In order to learn whether the re-transplantation of the MY-mouse is possible or not, further experiments were carried out. First, this tumor was successfully re-implanted into mice from which the tumor was removed by ligation. The results were summmarized in Table 3. It is interesting that the re-transplantation into D-103 mice showed entirely negative in result, while in S-4 mice 33.3 percent showed a positive re-transplantation. In F₁ (D-103×C3H) hybrids, all experimental individuals were positive in result, while the F₂- and RF₁-hybrids were wholly negative. The sarcoma was re-transplanted into the host bearing the MY-mouse sarcoma. In the latter case, D-103 mice showed a positive re-transplantation in 26.6 percent (Table 4). From the results of the above experiments, it is highly apparent that the transplantability of the tumor which developed in the mice of non-pure strain is to be controlled by some genetical factors in addition to histocompatibility genes.

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