76 MR. W. BATESON ON COLOUR- HEKEDITY [May 26, 



inter se, and found that some pairs gave the expected mixture, 

 while others gave dominants only. Qualitatively therefore the 

 result is the normal one. It is not stated that the " extracted" 

 albinos were tested, but there is little doubt that, in accordance 

 with almost universal experience, they would have produced 

 nothing but albinos. 



A leading fact illusti-ated by Ouenot's experiments, viz. the 

 recessive nature of albinism, is borne out by the whole series of 

 experiments under review. The fact is true of albinos in mice, 

 rats, guinea-pigs * (Cumberland, 13 ; Castle, 7), and rabbits 

 (Castle), so far as experiments have reached. Cases of the pro- 

 duction of albinos by coloured i-abbits (e. g. Polish by Dutch, 

 albinos by silver-gi'eys) are frequent in the fancier's literature. 

 The contrary, the production of coloured animals by albinos, is 

 not, so far as I know, illustrated by a single case, with the 

 following exception. In the later editions of ' Fancy Mice ' 

 (TJpcott Gill), Dr. Cai'tei- Blake, foi-merly secretary of the 

 Anthropological Institute, commenting on the statement that 

 albino mice of whatever parentage produce nothing but albinos, 

 writes (p. 16) that a pair of albinos produced some brown- and - 

 white, some plum, some grey, and some albinos. If this restilt 

 occurred under all precautions, it stands alone. 



Nevertheless we should be cautious in declaring the I'esult 

 impossible, for in Mendelian experiments the observer must be 

 on the look out for the appeai-ance of a character, elsewhere a 

 definite dominant, as the consequence of crossing tioo dissimilar 

 recessives. ISTot only may a dominant colour be produced by 

 crossing two forms having a recessive colour, — e. g., purple flowers 

 by crossing the Avhite Datura Icevis with white I), ferox ; purple 

 flowers in Sweet- Pea by crossing white " Emily Henderson " 

 round-pollened form with the long-pollened form of the very 

 same white variety ; purple flowers in the Stock by crossing two 

 white varieties : — but also a dominant sbntctuixd character, hoariness, 

 may be produced by crossing glabrous (recessive) stocks of dif- 

 ferent colours, e. g., red and cream, or red and white t. In each of 

 these cases the appearance of an atavistic character occurs as a 

 consequence of the union of gametes bearing dissimilar characters ; 

 but the character in which the reversion appear^s is of a class 

 difl:erent from that in which the parental differentiation was seen. 



The same may very possibly be true of animals also. But in 

 each of the cases known, the two varieties united, though alike 

 bearing the same recessive character, differ obviously in some 

 other respect ; and we know that the cross-bred raised by their 

 union is a heterozygote, i. e. a zygote formed by the union of 

 dissimilar gametes. It is, I think, scarcely likely that Carter 

 Blake's case of the mice is really to be so regarded, and on the 

 whole the hypothesis of error is more probable ; but the possibility 



* Small « smudges " are said to occur irregularly in albino cavies, however pure 

 t Ihis statement is based on results of experiments made by Miss E. R. Saunders 

 as yet unpublished. ' ' 



