COAT CHARACTERS IN GUINEA-PIGS AND RABBITS. 43 



in Table G really produce a full quota of albino gametes, and that 

 these are entirely fertile when they meet gametes transmitting black, 

 either active or latent.* 



It is a question of much interest, theoretical as well as practical, 

 whether animals of a particular type, when produced by cross-breed- 

 ing, form the same sort of gametes as are produced by pure-bred 

 animals of the same type. In the case of albinos this evidently is not 

 always true. From an albino which forms gametes all of which trans- 

 mit latent black, there may be produced, as we have seen, by cross- 

 breeding with a red animal and then interbreeding the hybrids, albinos 

 of three different sorts as regards the transmission of latent black 

 pigment. Again, the character of a red race which breeds true may 

 be modified by cross-breeding with black, resulting in the production of 

 yellow young. Thus two red animals, young of black (red recessive) 



red & ? red $2007 



red A 2004 red 2 2036 bl.?20!3 red A 2054 red ? red $ 2007 



I I I | I ' I 



-J- -[- -j- 



red 2 1307 bl. (red recessive) A 1180 red 2 2027 

 I | t J 



HT ~T~ 



red 2 3096 red 3082 



3 yellow young 



FIG. ii. A genealogical table showing how cross-breeding between red and black may cause variation 



in the intensity of the red. 



^ 1180, by two different pure-bred red females, when mated together, 

 produced a litter of 3 yellow young. The relationships involved will 

 perhaps be more readily understood from the above diagram (fig. n). 

 Apparently the cross with black induced variation in the intensity of 

 the pigmentation transmitted by the gametes bearing red, so that some 

 of the zygotes which were formed bore the dilute form of red, viz, 

 yellow. 



BLACK-EYED WHITE. 



Guinea-pigs of this sort have hair and skin very free from pigment, 

 indeed in the integument of the living animal I can detect no pigment 

 at all, yet the eyes are black pigmented. Two animals of this sort 

 have been born in the course of my experiments, and I have likewise 

 experimented with two others obtained by purchase. They are not 

 albinos and do not contain recessive albinism, at least those which I 

 have had do not. They are of spotted parentage and may be considered 

 spotted animals in which the typical pigment patches show an extreme 



* Experiments made since the foregoing was written show that albinos free 

 from latent black are entirely fertile inter se. Further, the deficiency of albinos 

 observed at first is now disappearing. 



