GUINEA-PIGS FROM ICA. 29 



do the same. Race C, like the lea race, contains only an occasional 

 individual sparingly spotted with white; yellow spotting is of course 

 not visible in a race like C, which contains only yellow or albino indi- 

 viduals. It will suffice to say that the cross-breds, like the parent races, 

 consisted principally of self-colored individuals, and that only an occa- 

 sional dark-eyed individual bore white markings, which in no case were 

 extensive, but were usually limited to a white foot. Among the red- 

 eyed individuals, white spotting was commoner and more extensive, 

 which might seem surprising, unless one remembers that in red-eyed 

 individuals it is impossible to distinguish true white spotting from 

 yellow spotting, since both produce uncolored areas in the coat. Com- 

 plications of this nature make this cross unfavorable for the study of 

 the inheritance of spotting. 



SUMMARY ON THE ICA RACE. 



1. The "lea race" of guinea-pigs consists of descendants of 1 male 

 and 2 female golden agoutis obtained from the vicinity of lea, Peru, 

 in 1911, and reported to have been caught wild. These animals are 

 supposed to have been descendants of guinea-pigs long since escaped 

 from domestication. 



2. This explanation is supported by the observation that within the 

 lea race have cropped out 5 Mendelian variations which are common 

 among domesticated guinea-pigs, viz, (1) the "red-eye" variation, one of 

 the four allelomorphic forms of the color factor in guinea-pigs; (2) the 

 "non-agouti" allelomorph of the agouti factor; (3) the factor which 

 produces rough coat; (4) the factor for white spotting; and (5) the 

 factor for yellow spotting. 



3. An albino guinea-pig of race C differing from wild guinea-pigs by 

 4 recessive Mendelian characters was crossed with golden agouti 

 females of the lea race. From this cross were obtained in F 2 all except 

 one of the expected recombinations of the 4 unit-factor differences 

 between the races crossed. Leaving out of consideration spotting 

 with white and with red, which occurred among some of the hybrids as 

 well as in the uncrossed lea race, there occurred 5 easily distinguishable 

 classes of dark-eyed young and 5 classes of red-eyed young, besides 

 albinos. Only one "expected" class of F 2 young was missing, the 

 occurrence of which among other races is well known. There is almost 

 an even chance for its failure to appear in this experiment in the number 

 of young recorded. 



4. The four color factors involved in the cross and their allelomorphs 

 are: 



A, a = agouti, non-agouti; 



B, b = black, brown; 



C, C r = full color, red-eye; 



E, e = extension (of black or brown), restriction. 



