

INHERITANCE IN (iUINEA-PIGS. 



the pink-eye variation with colored coat, first brought to the attention 



cientiste in the case of mice through the experiments of Darbishire 



1902 . \ similar variation has, however, since been found to occur 



in rate | astle,1914). Thenumberof factors in which <? 1002 is hetero- 



goua i- surprisingly large and implies doubtless considerable cross- 



breeding in the guinea-pig colonies kept by the natives of Arequipa, a 



- perhaps connected with the great size and vigor of their animals. 



The factorial constitution of 6*1002, as at present understood, is as 



follows: 



(1) Agouti factor, An. agouti-marked but transmitting non-agouti as a recessive 



character. 

 2 Black factor, BB, homozygous. 



Color factor, C,iC r , two different recessive variations, dilution (Cd) being 

 dominant over red-eye (C r ). Both are recessive to ordinary intense color 

 ( ' and dominant over albinism (C a ), the four forming a series of quadruple 

 allelomorphs, us shown by Wright (1915). 

 Extension factor, EE, homozygous. 



Dark-eye factor, Pp, heterozygous for the recessive pink-eye (p) variation, 

 with which goes dilution of black or brown pigments, but not of yellow. 



(6) As regards the rough variation, this animal is smooth, but nevertheless trans- 



mit- occasionally a trace of the rough character, but the character does not 

 crop out among his descendants in any as yet recognizable Mendelian 

 proporl 



(7) White spotting, homozygous. 



(8) Yellow spotting, homozygous. 



cation of young obtained from matings of c?1002 with unrelated guinea-pigs. 



Male 1002 waa mated with 20 dark-eyed guinea-pigs and 6 albinos 



derived either from race B, from a 4-toed race (see Castle, 1906), or 



in crossee between the two. Both these races contain only non- 



agouti animals. The dark-eyed mothers produced 70 Fj young, the 



ilbino mothers produced 18 F! young. Disregarding spotting with 



yellow and with white the young of the dark-eyed mothers fall into 



elates dark-eyed intense, dark-eyed dilute, and red-eyed— and 



h class may be further subdivided into agouti and non-agouti. (See 



table i 



I he albino mothers, though derived from the same races as the dark- 



1,1 mother, produced only two of the three main classes of young, 



dark-eyed dilute and red-eyed, which fact confirms Wright's (1915) 



