2!»J: Mr Batesous Revisiom of Memlels Theory of Heredity 



Mr Barbishire's liesults und Mr Bateson's First Explanatioti. 



The inice used by Mr Darbisliire are normal pink-eyed albinos, of various 

 aucestry, and a race of "Japanese" waltzing mice, having pink eyes and u piobald 

 (fawn-coloured and white) coat. The normal albino mouse is said by Crampe, and 

 by muny moiise-breeders, to breed perfectly true, whatever its ancestry, and 

 Mr Darbishirc'.s albinos certainly so far do so. The waltzing mice also breed true 

 in the sense that their offspring always waltz, and ahvays have pink eyes with 

 a fawn-and-white coat ; but there are of course slight variations in the size and 

 shapc of the coloured patches. There is no proof that the results of reciprocal 

 crosses between these two races are different. Thercfore, siuce these two races each 

 breed true, and give similar results in reciprocal crosses, they satisfy the conditions 

 of "gainetic purity " laid dnwu by Mr Bateson, and there is no reason to assume 

 that Mr Bateson's remarkable hyjjothesis of a ditfercnce in constituti(jn between 

 the male and female gametes appiies to either. 



The Jirst hyhnd generation, directly resulting from the cross, is so far constant 

 in two respects ; none of the individuals " waltz," and all have pigmented (dark) 

 eyes. In coat-colour the hybrids are very variable ; none have the für entirely 

 white, but the colour, and the extent of the coloured patches, vary widely. As to 

 the aniount of white fui-; out of 203 mice available when Mr Darbishire's last 

 Report was published, he teils me that one had no white für; üü had white 

 ou the belly only; 51 had some white on the back and sides, but less than in 

 pure-bred waltzing mice ; 30 had about the same amount of white as a waltzing 

 mouse, and 3 had niore. The colour of the coloured für was yellow in 7 cases, 

 a pale or dark " wild-colour," like that of the wild mouse, in 138 cases, aud blcu;k 

 in 9 cases. 



The nniformly dark colour of the eyes is diflficult to explaiu on any Mendelian 

 hypothesis ; for since pink eyes may coexist with a coloured coat, and dark eyes 

 with a white coat, it is clear that in many cases at least eye-colour and coat- 

 colour can be separately inherited, and should therefore on Mendel's view be 

 represented by separate gametic elements. But we are told by Mr Bateson, and 

 on better evidence by von CJuaita, that albinism is a recessive character; and it 

 seems natural to suggest that "albinism" is a "Compound" character, composed 

 of two or moro elements, amoug which are wliiteness of coat and pinknoss of eye. 

 On this view, the; two purely recessive cye-colours of Mr Darbishire's mice should 

 give pink eyes wheii crosscd ; and we See that they do not. No Mendelian 

 h3-potiiesis will account for the production of a new or atavistic ej'e-colonr by the 

 Union of similar elements; and therefore, altliough eye-colour is certainly separable 

 from wliiteness of coat, because dark-eyed mice with white für are well known ; 

 although it is similarly separable from a fawn-coloured-and-white coat, because 

 among the offspring of Mr Darbishire's hybrids fawn-and-white individuals occur, 

 some dark-eyed and some pink-eyed, yet a method must be devised by which this 



