GUINEA-PIGS FROM AREQUIPA. 41 



SUMMARY ON THE AREQUIPA DOMESTICATED RACE. 



1. A domesticated male guinea-pig obtained from the cabin of a 

 native in Arequipa, Peru, has proved to be of great interest because of 

 the large number of color mutations which it either possesses or trans- 

 mits without itself manifesting them. Two wholly new variations 

 (red-eye and pink-eye) were obtained from this animal as recessive 

 characters. The former has been obtained subsequently from the lea 

 race and the latter from a race of guinea-pigs brought from Lima by 

 Professor Brues. Both are probably variations of long standing 

 among the guinea-pigs kept by the natives in Peru, but seem not previ- 

 ously to have been observed among guinea-pigs in Europe or North 

 America. 



2. Red-eye is a Mendelian allelomorph of albinism, of dilute pig- 

 mentation, and of intense pigmentation, the four being quadruple alle- 

 lomorphs (Wright, 1915). A gamete may transmit one of the four, 

 but not more; a zygote may contain and transmit (separately) two of 

 the four, but not more. Dominance is in the order of decreasing 

 intensity, viz, (1) intensity, (2) dilution, (3) red-eye, (4) albinism. 

 Intensity and dilution affect all pigments similarly; red-eye and albin- 

 ism inhibit yellow completely, but affect black in very different de- 

 grees, the inhibition of black being nearly complete in albinism, but 

 being partial only in red-eye. Red-eye is a variation unknown as yet 

 in any other animal, but the sooty coat of young Himalayan rabbits 

 possibly is a parallel variation, and the same may be true of Siamese cats. 



3. Pink-eye is a variation wholly independent genetically of albinism. 

 It affects only black (or brown) pigments, the intensity of yellow pig- 

 ment being unimpaired in its presence. A similar variation (genetically 

 and physiologically) occurs in mice and also in rats. 



4. The new variations (red-eye and pink-eye) have formed, with the 

 previously known unit-character variations of guinea-pigs, many new 

 unit-character combinations, which are here described. 



5. From the crosses of the Arequipa domesticated guinea-pig with 

 other guinea-pigs, involving a maximum number of color factors, no 

 evidence is forthcoming that any two of the factors are " coupled" or 

 "linked." 



