20 INHERITANCE IN GUINEA-PIGS. 



HYBRIDIZATION EXPERIMENTS WITH A RACE OF FERAL 

 GUINEA-PIGS FROM ICA, PERU. 



ORIGIN AND CHARACTERISTICS OF THE ICA RACE. 



Von Tschudi in 1844, in his Fauna of Peru, described, under the name 

 of Cavia cutleri, a wild cavy found occurring in great numbers in the 

 state of lea. He says that the natives call it "cuy del monte," the 

 mountain cavy, and regard it as the original of C, cobaye, the guinea-pig. 

 Subsequent writers carefully distinguish the C. cutleri of Von Tschudi 

 from that of Bennett, with which my wild cavies from Arequipa agree. 

 One of the objects which I hoped to accomplish by the trip to Peru was 

 to learn more about the cavy which Von Tschudi reported as occur- 

 ring at lea, and, if possible, to determine its relation to C. cutleri Bennett 

 and to the guinea-pig. 



Through the kindly interest of Messrs. W. R. Grace & Co. I was 

 able to secure 3 wild-caught cavies (a male and 2 females) from lea 

 and to bring them back with me to the Bussey Institution, where they 

 have produced a numerous progeny. 



These animals were about the size of domesticated guinea-pigs, were 

 very timid, and were self-colored golden agouti, in every respect similar 

 in appearance to tame guinea-pigs of the color variety named. 



The 3 animals brought from lea produced 7 golden-agouti young, 

 all similar to the parents in color, except that one bore a spot of red, 

 the first observed indication of contamination of the stock with char- 

 acters found in domesticated guinea-pigs. That other indications 

 were not observed in this first mating of the animals was probably due 

 to the fact that the male was homozygous for all other color factors, as 

 subsequent rnatings of the females with a son of one of them by the 

 original male proved that both mother and son were heterozygous in 

 that variation of the color factor which is seen in " red-eyed" guinea- 

 pigs (Castle, 1914; Wright, 1915). The same matings with the son 

 (c?505, table 12) proved that one of the two original females (9503) 

 was also heterozygous in the agouti factor and transmitted white- 

 spotting, since she produced a black daughter which had one white foot. 

 Three other inbred descendants of the original trio of lea animals have 

 also borne spots of white; two of them in addition bore spots of red, 

 and so were tricolors. One of the original trio of animals from lea 

 (9502), when mated with c?505, produced a son (d"575) which was 

 imperfectly rough-coated. Accordingly we have clear evidence that 

 the stock derived from lea was contaminated with at least 5 of the 

 supposedly independent unit-factor variations which occur among 

 domesticated guinea-pigs and there can be little doubt that it really has 

 been derived wholly or in part from domesticated guinea-pig ancestors. 



