9 o 



Experimental Zoology 



the eyes the color, t C, always dominates; but the color of the 

 hair is yellow, because yellow dominates over black. 



The four types with which Cuenot has experimented give 

 eighteen different combinations, which he shows by means of 

 the following table : - 



Of these eighteen types there are six that are pure races, 1 i.e. 

 they produce germ-cells that are all alike (homozygotes). In- 

 bred, they give always the original types in all successive gen- 

 erations, and this holds also for the three albino types, having 

 the latent characters gray, black, and yellow, AG, AB, and A Y. 

 The other twelve types are heterozygotes, resulting from the 

 crossing of pure races. Of these, nine are monohybrids, hav- 

 ing only one pair of antagonistic determinants; and three are 

 dihybrids, having two pairs of antagonistic determinants. 



It will be seen that Cuenot thinks that albinos are not nec- 

 essarily all alike, although they may breed true to the albino 

 type, but that they are different according to the latent char- 

 acter that each contains. The latent character may appear in 



1 According to Cuenot's nomenclature. The three 'albinos, homozygotes, be- 

 long in my opinion to a different category, for although they breed true, yet they 

 contain a latent color that may come out in crossing. 



