Masao So and Yoshitaka Imai 325 



And out of five males coming from the cross " Kasuri " x " Kasuri," one 

 carried the self factor in the homozygous condition and three in the 

 heterozygous one, one being doubtful : only one of the females from a 

 similar mating gave a litter and proved to be a heterozygote. 



These results almost exactly confirm the expectation, though a defi- 

 ciency of homozygous mice was observed in the cross heterozygous self x 

 " Kasuri." 



When such resulting heterozygous " Kasuri " mice are crossed with 

 the ordinary piebald, four types of young are produced in almost equal 

 proportions, as was shown before. If, however, the " Kasuri " race homo- 

 zygous for S is mated with piebald, we should expect ' Kasuri " and self 

 in nearly equal numbers. The results obtained from these crosses are 

 summarized in the following table : 



" Kasuri " Self Totals 



Observed 59 54 113 



Expected 56*5 56-5 113 



In this case the agreement between actual and calculated numbers 

 is close. 



Further experiments with the "Kasuri" race of SSDd composition 

 were rendered difficult owing to its tendency to become sterile and its 

 weakness. 



Mating : " Darunia " x Piebald. 



As was mentioned above, the " Daruma " race normally hsis dark eyes, 

 black or brown, according to the nature of the coat colour factor which 

 the animal carries. But Detlefsen obtained a pink-eyed " Daruma " 

 race which is almost indistinguishable from the albino in appearance. 

 The writers also have often raised such a mouse as well as a ruby- 

 eyed one. 



The " Daruma " race has usually a pure white coat, but often it is 

 blemished by a spot or spots appearing between the eyes, around the 

 ears or in fi-ont of the tail, etc., and, though rarely, such spots form fine 

 silvered markings scattered over the coat as in the whiter forms of 

 the " Kasuri " pattern. Furthermore, in a few cases, such spots may 

 assume somewhat large massive markings resembling the slightly spotted 

 classes of the ordinary spotting. In these cases it cannot be decided 

 whether the animal belongs to the "Dai-uma" race or not, without 

 the test of breeding. 



On crossing the " Daruma " race from various origins with the 

 normal piebald, two sorts of young invariably result, almost in an equal 



