PHYSICAL CHARACTERS IN MAN 69 



(white petals). The monograph above mentioned 

 also includes a study of seasonal variation in animals 

 that are white in winter, such as Lepus variabilis in 

 Scotland. Crosses of white and black Pekinese does 

 are also believed to furnish evidence of the de novo 

 origin of spotting and blends. It is well knr^wn, 

 of course, that in certain breeds, as the Dalmatian, 

 particular types of spotting have become a fixed 

 characteristic of the breed. Numerous Mendelian 

 studies of spotting in mammals have been made in 

 recent years, especially in rabbits, rats, and mice, 

 and complicated theories of inheritance of spotting 

 have been formulated. The subject is complex and 

 far from settled, but it seems clear that in man}^ cases 

 degrees of spotting and their inheritance can be 

 explained on the basis of a series of factors for spotting. 

 The evidence clearly indicates, I think, the sporadic 

 de novo origin of spotting in man, but it does not 

 follow that the same is necessarily true for dogs. In 

 some breeds spotting, however attained, has the status 

 of a germinal factor, and the regularity with which 

 white-black crosses of Pekinese yield definite patterns 

 would seem to indicate another mode of heredity 

 behaviour — i.e., that a spotting or pattern factor is 

 present in these crosses. 



Detlefson (1920) has described a herd of albino 

 cattle on a farm in Minnesota with several points of 

 interest. This herd originated from two albino 

 calves — a bull and a heifer — which resulted from 

 mating a " full-blooded " Holstein bull with " grade " 

 Holstein cows. The parents had the normal black- 

 and-white spotted coat colour, while the calves were 



Standley (192 1) refers to an early American record of an albino 

 black bear with " four cubs, one white, with red eyes and red 

 nails, like herself," showing that albinism must have been 

 carried as a recessive in the strain. 



