GUINEA-PIGS FROM AREQUIPA. 33 



conclusion that albinos, even when derived from intense dark-eyed 

 parents, do not transmit intensity to their young in crosses, for the 

 reason that albinism is an allelomorph of dilution as well as of intensity. 

 The fact that d" 1002 produced no albino young, even when mated with 

 albinos, shows that he did not produce albino gametes. The fact that 

 he produced red-eyed young when mated with albinos shows that he 

 transmitted red-eye as a recessive character and that this is dominant 

 over albinism. The fact that he produced no intense dark-eyed young 

 by the albino mothers shows that he lacks intensity and forms only 

 gametes which transmit either dilution or red-eye. All these facts are 

 in harmony with the hypothesis suggested by Wright (1915) that inten- 

 sity, dilution, red-eye, and albinism are allelomorphs of each other, so 

 that a gamete can transmit only one of the four allelomorphs, and a 

 zygote can contain only two of them. Male 1002 is evidently a hetero- 

 zygote of dilution and red-eye (C d C r ), both of which are recessive to 

 intensity (C) and dominant over albinism (C a ). Consequently, when 

 he is crossed with albinos, zygotes of two sorts are expected in equal 

 numbers, viz, C d C a and C r C a (dilute and red-eyed), as observed (table 

 19) ; and when he is crossed with intense dark-eyed animals carrying 

 albinism as a recessive character (as 15 of the 20 dark-eyed mothers of 

 table 19 did), zygotes of four sorts are expected in equal numbers, viz, 

 CCd, CC r , C d C a , and C r C a , the first two being dark-eyed intense, the 

 third dark-eyed dilute, and the fourth red-eyed. The observed result 

 is in perfect accord with this expectation as regards the classes of young 

 produced, and agrees with expectation sufficiently well as regards the 

 proportions of the classes. 



It is expected further that each of the three main classes will be sub- 

 divided about equally into agoutis and non-agoutis. The 6 expected 

 subclasses appear in the experimental results, but there is a considerable 

 excess of agoutis, viz, 56 agoutis to 32 non-agoutis. Whether this depar- 

 ture from the expected equality has any probable significance will be 

 considered further in connection with the F 2 generation. 



F 2 OFFSPRING OF cflOOl 



For the production of an Fa generation a golden agouti and 4 silver 

 agouti males were selected. The golden agouti male was mated only 

 with a black female, his sister, but the silver agouti males were mated 

 with practically all classes of the F x females. (See table 20.) They 

 produced altogether 190 F 2 young, which, being classified as regards 

 intensity and eye color alone, fall into 6 main classes, viz, (1) dark-eyed 

 intense, (2) dark-eyed dilute, (3) red-eyed, (4) pink-eyed, (5) red-and- 

 pink-eyed, 1 and (6) albino. Each of these main groups falls into two 



1 Animals called red-and-pink-eyed are in reality pink-eyed, but lack yellow in the coat. They 

 transmit in every gamete both the factor for pink-eye and the factor for red-eye. 



