THE TYPES OF SPOTTING IN MICE AND 

 THEIR GENETIC BEHAVIOUR'. 



By MASAO s6 and YOSHITAKA IMAI. 



(With Plate XII.) 

 CONTENTS. 



PAGE 



Introduction 319 



Material used 321 



Mating: Self x Piebald 321 



Mating: " Kasuri " x Piebald 322 



Mating : " Kasuri " x Self 323 



The " Kasuri " Kace carrying Self Factor in the Homozygous Condition . 324 



Mating: " Daruma " x Piebald 325 



Mating: "Daruma" x " Daruma" 326 



The Modified Ratio 326 



Mating :" Daruma " X Self 327 



Mating: " Kasuri " x " Daruma " 328 



Mating : " Kasuri " x " Kasuri " 328 



The Behaviour of the D Factor 329 



Extracted Self and Piebald 330 



Explanation of Plate 332 



Literature cited 332 



Introduction. 



The manifold types of the coat pattern in mice as well as in other 

 rodents have furnished convenient material for genetic investigation. 

 Spotted or piebald type is a well-known variation in these animals. 

 Utilizing this form in breeding experiments, the results obtained by 

 different authors arrive at the same conclusion, i.e. on the whole the 

 spotting behaves as a recessive to the self-coloured. 



In rats the type of the spotting is somewhat limited as it hardly 

 varies beyond the limits of the hooded marking. On the other hand, 



' A preliminary paper (in Japanese), with a description on the inheritance of albinism 

 in mice, was published in the Journal of the Scientific Agricultural Society, No. 187, 1918. 



Joum. of Gen. ix 21 



