Masao So and Yoshitaka Imai 323 



11. A factor, D, acts as epistatic upon the former allelomorphs in 

 the following ways : When the animal carries S, D works upon this, and 

 the development of the pigment on the coat is restricted to a sort of 

 spotting resulting in the " Kasuri " pattern ; when S' takes the place of 

 S, the pigment is almost entirely inhibited its development except as to 

 the eyes. And d (an alternative mate of D factor) may be regarded 

 apparently as having no influence upon its hypostatic allelomorphs, 

 S and S'. 



If the assumption is correct that the " Kasuri " race used in these 

 matings was doubly heterozygous as to the allelomorphs above repre- 

 sented, everj' form resulting among the offspring may be expected in 

 almost an equal ratio in every cross, for the genetic composition of the 

 piebald is invariably S'S'dd. 



The crossings of this sort were made reciprocally, but no marked 

 difference is detected between them. In the following table there are 

 given the totals of the reciprocal results obtained from such a sort of 

 mating ; 



On the whole the numbers obtained agree to the expectation, though 

 there is observed some marked discrepancy of the ratio. 



Mating : " Kasuri " x Self. 



When such a doubly heterozygous " Kasuri " race is crossed with self 

 the results expected are different, depending upon the genetic composi- 

 tion of the latter animal. If homozygous selfs are used in this sort of 

 mating the offspring consist of "Kasuri" and self in almost equal numbers, 

 the actual results being as follows : 



The deviation from equality is somewhat large, and may be either a 

 chance deviation, or the consequence of the selective mortality among 

 the young, as it was often conspicuously observed in this sort of mating. 



When the heterozygous selfs, however, are mated with this race the 

 expected ratio is a 3:1 :3: 1 ratio of "Kasuri," "Daruma," self, and piebald 

 respectively. In the following table are represented the results obtained : 



