306 MB. C. C. HUEST : EXPERIMENTAL STUDIES 



Colour-factors latent * in JPure-hred Albinos. 



The 2 albino Angoras originally used in the experiments 

 were tested by mating them with the pure blacks of the second 

 generation. No. 2 albino buck mated with 4 black does gave 

 16 black young. No. 3 albino doe mated with a black buclc 

 gave 11 young, of whicb 5 were black and 6 were grey. These 

 results are in accordance with the conception that No. 2 albino 

 gave off gametes, all of which carried the black factor, while 

 No. 3 albino gave ofl" gametes, some of which carried the black 

 factor and others the grey factor. 



To test the matter still further, No. 2 albino was mated with 

 5 grey hybrids known to contain recessive black, producing 38 

 coloured young, of which 21 were greys and 17 were blacks. 

 If, as conceived, No. 2 albino was carrying latent black simply, 

 the Mendeliaa expectation in this mating is 19 greys and 19 

 blacks. Again, No. 3 albino was mated with 2 grey hybrids 

 known to contain recessive black, producing 7 coloured young, of 

 which 5 were greys and 2 were blacks. These numbers are few, 

 but if, as conceived, No. 3 albino was carrying both latent grey 

 and latent black factors, the Mendelian expectation for 8 young 

 is 6 greys and 2 blacks. This conception also explains certain 

 facts in regard to the gametic constitution of the individuals of 

 the first generation which are otherwise obscure. It will be 

 remembered that while all the greys of the first generation by 

 the No. 2 albino were hybrids containing recessive black, yet 

 one individual grey (No. 7) out of No. 3 albino was a pure grey 

 containing no black. The above conception that No. 2 albino 

 gave off all black gametes, while No. 3 albino gave off both grey 

 gametes and black gametes would explain the above facts, which 

 were previously obscure. 



In order to test whether these latent factors in albinos were 

 subject to Mendelian segregation in simple albino matings, the 

 No. 3 albino doe, apparently carrying grey and black, was mated 

 with No. 2 albino buck, apparently carrying black only. 14 

 young were produced, all albinos, of course, with no trace of 



* To prevent niisconception it should be stated that the colour-factors present 

 in albinos are " latent " in the sense that their influence is not evident until some 

 other ingredient, found in a pigmented individual, is added to them. When 

 the precise nature of pigmentation is determined, it may be possible to substitute 

 a more precise term. {Cf. Cuenot, 1903.) 



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