R C. PUNNETT 237 



colourless in the Himalayan. This peculiarity of the Himalayan is 

 strikingly brought out in some experiments made by my friend Mr 

 T. H. Riches. An ordinary black Himalayan was crossed with a black- 

 and-tan rabbit, and in F^ came normal black Himalayans together with 

 " Himalayised " black-aud-tans. These last were characterised by the 

 markings of the black-and-tan with the difference that the yellow of 

 the nose, ears, and paws of the full-coloured form was replaced by white 

 in the corresponding Himalayan. The facts seem to suggest that the 

 Himalayan pattern is deterniined by the absence of yellow, the pre- 

 sence of this pigment being necessary for the full development of the 

 melanin series. Yet tempting as such a hypothesis is, there are difficulties 

 in the way of its acceptance — difficulties which are at once evident when 

 the relations of the Himalayan and the true albino are considered. 

 Since the albino behaves as a simple recessive to the Himalayan the 

 lack of colour in the two cases must be regarded as resulting from the 

 same cause, the only necessary difference between them presumably 

 being in the presence or absence of a factor which determines the 

 pigmentation of the points. Again the self-coloured rabbit behaves 

 as a simple dominant to the Himalayan, and consequently must be 

 supposed to contain the factor producing the pigmented points in the 

 Himalayan in addition to the factor for yellow, which on this hypothesis 

 the Himalayan lacks. Hence the ordinary self-coloured rabbit should 

 contain two factors both lacking in the full albino, viz. the Himalayan 

 point factor, and the yellow factor. The F„ from self x albino should 

 consequently contain Himalayans as well as true albinos. But among 

 the large number of animals reared from such matiugs no Himalayans 

 have hitherto been recorded, and for the present the relations between 

 these various forms remain obscure. 



Lastly there is a small point in connection with what Castle has 

 termed " mosaic" Himalayans ((1), p. 70). My experiments have shewn 

 that in F., from Dutch x Himalayan the majority of the coloured animals 

 are more or less marked with white, the amount of which varies between 

 that found in typical Dutch to a sn)all white patch on the tip of the 

 nose or one of the paws. These white markings, generally in-egular, 

 occur also in the F. Himalayans from the Dutch cross. Sometimes 

 there is a white spot only on the nose, sometimes one or more paws 

 are tipped with white. In other cases an F., Himalayan may be a full 

 Dutch Himalayan when the only pigment found is on the eai-s and tail 

 together with a small strip on either side of the nose, all the feet in 

 such animals being completely white as in the Dutch. Such animals 



Journ. of Gen. ii 17 



