Chap. IV. THE IIIMALArAXT bhEED. 115 



certain parts of their bodies, and are tlien called Himalayans. 

 The young Himalayans, however, are sometimes at first 

 either pale grey or completely black, in either case changing 

 after a time to white. In a future chapter I shall advance 

 a large body of facts showing that, when two varieties are 

 crossed both of which differ in colour from their parent-stock, 

 there is a strong tendency in the young to revert to the 

 aboriginal colour ; and what is very remarkable, this reversion 

 occasionally supervenes, not before birth, but during the 

 growth of the animal. Hence, if it could be shown that 

 silver-greys and chinchillas were the offspring of a cross 

 between a black and albino variety with the colours intimately 

 blended — a supposition in itself not improbable, and supported 

 by the circumstance of silver-greys in waiTens sometimes pro- 

 ducing creamy- white young, which ultimately become black — 

 then all the above given paradoxical facts on the changes of 

 colour in silver-greys and in their descendants the Himalayans 

 would come under the law of reversion, supervening at dif- 

 ferent periods of growth and in different degrees, either to tlie 

 original black or to the original albino parent-variety. 



It is, also, remarkable that Himalayans, though produced 

 BO suddenly, breed true. But as, whilst young, they are 

 albinoes, the case falls under a very general rule ; albinism 

 being well known to be strongly inherited, for instance with 

 white mice and many other quadrupeds, and even white 

 flowers. But why, it may be asked, do the ears, tail, nose, 

 and feet, and no other part of the body, revert to a black 

 colour ? This apparently depends on a law, which generally 

 holds good, namely, that characters common to many species 

 of a genus — and this, in fact, imjdies long inheritance from 

 the ancient progenitor of the genus — are found to resist 

 variation, or to reappear if lost, more persistently than the 

 characters which are confined to the separate species. Xow, 

 in the genus Lepus, a large majority of the species have their 

 ears and the upper surface of the tail tinted black ; but the 

 persistence of these marks is best seen in those species which 

 in winter become white : thus, in Scotland the L. ranahilis^^ 



'" G. R. Waterhouse, ' Natural History of Mammalia : Rodents,' 1846, pp. ."A 

 60, 105. 



I 2 



