Masao So and Yoshitaka Imai 329 



of zygotes in respect to the genotype and four kinds as regards the 

 phenotype. But actually, subsequent death of the embryos homozygous 

 for D would take place, so the ratio which is recognizable after birth of 

 the young is modified, as is represented in the following table : 



Genetic Original Observed 



Race composition ratio ratio 



"Kasuri" SS DD 1) 



SS'DD 2 I Q 



SS Dd 2 f ^ 2 



SS'Dd 4 ) 4 



"Daruma" SS'DD 1 ) „ 



S'S'Dd 2\ '^ 2 



Self ... SSdd 1 ) „ 1 ) „ 



SS'dd 2\ "^ 2 I ** 



Piebald ... S'S'dd 1 } 1 1 } 1 



On such an expectation the data obtained can be well understood. 



TAe Behaviour of the D Factor. 



Here an attempt will be made to show the total data on the inheri- 

 tance of the D factor, neglecting the other factors and their relation. 



In the next table there are summarized the results obtained from 

 the cross Dd x dd and its reciprocal : 



D d Totals 



Observed 893 981 1874 



Expected ..... 937 937 1874 



The data above represented agree passably with expectation, though 

 the numbers show some marked deviation. But this discrepancy of the 

 ratio is mainly due to the result of the cross SS'Dd x S'S'dd ; omitting 

 this the numbers are 706 D and 745 D, where expected 725'5D and 

 725'5d respectively. 



The results obtained from the cross Dd x Dd are summarized and 



represented below : 



D d Totals 



Observed 284 144 428 



Expected 285-33 14267 428 



An inspection of the above data shows that the expectation based 

 on a ratio 2 : 1 covers the results quite fairly. On the normal Mendelian 

 expectation one-third of the D factor bearing animals thus obtained 

 should be homozygous as regards this factor. The results, so far as 

 the writers' experiments went, showed that none of them contains the 

 factor in full doses. In all, twelve " Kasuri " (4 ? $ and ScfcT) and six 



