- 



IMIKHITANCE IN GUINEA-PIGS. 



.,. n DMtAmMm -..ty and dilution among the F 2 young derived 



from tht cross 9 race CX d'cutleri. 



oung. 



I 



( iiin.'tnion 



BUol How . 



Brow in jr*d jreltow 



la U 



Total 



in pain pro- 

 ducing no albinos. 



Intense. 



5 



• > 



5 

 2 

 1 



40 



Dilute. 



8 

 3 

 8 



2 



1G 



From pairs pro- 

 ducing albinos. 



Intense. 



2S 



6 



13 



10 



6 



7 



70 



Dilute. 



4 

 1 



4 

 2 



11 



It was expected thai albinos of race C would produce a much larger 



rtion of pale-colored grandchildren, but strange to say this expec- 



od was n- >i realised; 81 F 2 colored young produced in matings 



which yielded albinoe ahowing that the guinea-pig characters had been 



eived through albino gametes) included only 11 pale-colored young, 



of these is recorded as being paler in color than the cutleri 



grandparent. It would appear, therefore, that the albino gametes of 



I mothers do not transmit the dilution seen in the cream-colored 



animal- of race ( . This would be a puzzling state of affairs had not 



Wright 1915) already discovered an easy explanation for it, viz, that 



dilution of the cream race is an allelomorph of albinism, and so can 



be transmitted in the same gamete with albinism. 



I mparing the I', hybrids derived from race C crosses with those 



ived from race B crosses, it is certain that the pigmentation of both 



darker than that of wild C. cutleri, but the intensity of the race B 



hybrid- much exceeds that of the race C hybrids. Among the race B 



hybrid- do evidence can be discovered of segregating Mendelian inten- 



among the race ( ' hybrids dilution segregates as a simple 



Mendelian recessive, precisely as dors albinism, but apparently no 



garnet.- transmits both dilution and albinism, for the reason that they 



alternative conditions of the same factor. Aside from the factorial 



difference in dilution, how does race B differ from race C? Apparently 



in no simple factorial way, but iii a genera] way as regards energy of 



pigment production, in which hybrids of both races surpass C. cutleri 



if differ quantitatively from each other. No Mendelian explanation 



• Si difference is at present justified by the observations made. 



0) SIGN If 1 OF THE RESULTS OBSERVED. 



rmplete fertility of the hybrids produced by crossing wild Cavia 



i with the guinea-pig is in striking contrast with the sterility of 



bride between C. rvfi and the guinea-pig, as observed by Det- 



