104 ANNALS NEW YORK ACADEMY OF SCIENCES 



late, the offspring are black. This result is obvious on the explanation 

 here offered; for the factor that produces the abundant development of 

 the granules is supplied by the chocolate mouse, while the color of the 

 granules is determined by the dilute black parent. Such an interpreta- 

 tion is, as far as I can see, completely in accord with the facts, and I 

 venture to think that it offers some advantages over the schemata so far 

 offered, in that the peculiar relation between black and chocolate in 

 heterozygous black becomes more intelligible. In these mice, most of the 

 pigment is carried on to its higher stages, viz., black, some remaining, 

 however, at the lower stage; and the extent to which the process is car- 

 ried out depends on the physiological condition of the mouse at the time 

 when the hair is laid down. 



Asymmetrical Eye Colors 



In the winter of 1907, I procured from Dr. H. L. Wood, of Groton, 

 Conn., a dilute colored mouse that had one pink eye and one black eye. 

 The same condition reappeared again in one of my own mice, probably 

 related to Dr. Wood's. It is known that angora cats often have one blue 

 eye and one green one, and that coach dogs and other races, and man also, 

 sometimes have eyes of different colors, but I do not know of any other 

 records where one eye is black and the other pink (albino). The mouse 

 belonged to a strain of colored mice with pink eyes that Dr. Wood had 

 imported from England. Some of the mice were spotted with white, 

 which may enter also into the problem. I bred this mouse to other black- 

 eyed mice of the same stock, but obtained no asymmetrical offspring, 

 either in the first or in subsequent progeny. The condition appears, there- 

 fore, not to be inherited in the ordinary sense, but to be rather what I 

 have called an ontogenetic process of segregation which takes place for 

 this combination only rarely. Nevertheless, the phenomenon rests on the 

 same basis as that for the spotted condition in general, but in this instance 

 it is not fixed and appears only sporadically. I have had one other mouse, 

 as stated above, with one black eye and one pink eye from related stock, 

 but in none of its progeny did the condition reappear. In another com- 

 bination, I have found one mouse with one pink eye and one ruby eye. 

 The mouse itself was chocolate. 



Dilute Grays 



In the course of the large number of crosses that I have made between 

 different races of domestic mice, there have been produced some dilute 

 forms of gray. I mention these facts here not only to put on record the 



