Auttusr, 1901.] 



KNOWLEDGE. 



173 



brouglit about by the leplacemeTit of dark hail's by white 

 ones, aud uot by tlic blcat-hing of the former. In this 

 case, however, t'ne change, inst-ead of being seasonal and 

 sudden, is gi-atlual aud due to age. If the change was 

 due to blanching, wo should, of course, find sonic hairs 

 which were partially white and partially brown (or 

 black, as the case may be). Aud here it may bo re- 

 marked that if such partially blanched hairs were met 

 with, we should natui-ally expect to find that it would 

 be the basal half which was white, and the terminal 

 half which ret,tiued its natural colouring. lu other 

 words, precisely the reverse of the condition obtaining in 

 Sir John Ross" lemming ; thereby affording further 

 presumptive evidence as to the abnormal condition of 

 the change in that animal. 



As a matter of fact, however, those of us who have 

 reached an age when silver hairs have begun to make 

 their appearance among the brown can easily satisfy 

 themselves that such hairs are white throughout their 

 entire length, and that a hair half white and half brown 

 is quite unknown. From this we infer that the change 

 from brown to white takes place in human beings by 

 the gradual shedding of the dark hairs and their re- 

 placement by new ones from which pigment is entirely 

 absent. So that normally there is no such thing as 

 bleaching of individual hairs. The change is, indeed, 

 precisely similar to that which takes place at the ap- 

 proach of winter in mammals that habitually turn white 

 at that season, with the exception that, as a general 

 rule, it is extremely slow and gradual, instead of being 

 comparatively rapid, and also that the white hairs differ 

 from their dark predecessors solely by the absence of 

 colouring matter. Unfortunately, there is no subsequent 

 replacement of the white hairs by dark ones 1 



The fact that the change from brown to white in the 

 mountain hare (Lepus fimidus) is really due to a change 

 of coat and not to bleaching was known at a very early 

 period to the English naturalist. Pennant; and the 

 existence of this coat^change was likewise recognized by 

 Macgillivray. It was not, however, till Dr. J. A. Allen, 

 in a paper on the colour-change in the North American 

 variable hare published in the Bulletin of the American 

 Museum of Xatuial History for 1894, demonstrated by 

 actual experiment the truth of Pennant's statement that 

 the fact of the complete autumnal change of the coat in 

 animals that tiim whito in winter was generally recog- 

 nised by natou-alists. So far as the spring change from 

 the white to the brown dress is concerned, his conclusions 

 are fully confirmed by Mr. G. E. H. BaiTett-Hamilton, 

 who communicated some interesting notes on the change 

 in the European mountain, or variable hare to the 

 Proceed iny-: of the Zoological Society of London for 1899. 

 The fact that the vernal colour-change is due to a 

 shedding of the coat seems, however, as already 

 mentioned, to have been much more generally admitted 

 than was the case with regard to the autumnal 

 transformation. 



Dr. Allen arrives at the conclusion that both the 

 autumn and the spring change take place periodically 

 and quite independently of the will of the animal, and 

 also that they are but little affected by phases of the 

 weather, although they may be somewhat retarded or 

 accelerated by the prevailing atmospheric temperature. 



So far as the fact of the seasonal change being 

 normally beyond the control of the animal in which it 

 occurs, Mr. Barrett-Hamilton is in full accord with the 

 American writer; but he goes somewhat further, and 

 believes that it is quite uninfluenced by temperature, or 



at least by svu'li vai'iations of the same a,s may be met • 

 with in different parts of the area of the British Islands ; 

 and. as wo all know, these arc considerable ! 



As in the case of many other animals- -deer, for 

 instance — the change from the winter to the summci' 

 coat takes place very late in the sea.soii in the mountain 

 haro in Scotland, specimens undergoing the change being 

 often taken early in May. But the date of the spring 

 change is no earlier in tlie South of Ireland, where the 

 climate is much milder, although the amount of white- 

 ness assumed in that district is very much less than lu 

 the iiortli. This seems to demonstrato the contention 

 that temperature has little or no inllucnce on the change, 

 so far as season is concerned. 



That the animal has no control over the change from 

 brown to white in autumn seems to bo proved by 

 instances refen-ed to by Mr. Barrett-Hamilton, "' in 

 which variable hares transpoi-tcd from Scotland and from 

 Irish mountains to southern and low-lying regions con- 

 tinued for some seasons to appear in the northern garb 

 of snowy whiteness. This persistence of the habit of 

 turning white, even in unsuitable conditions, together 

 with the lateness of the moult, resulted frequently in the 

 curious spectacle of a mountain haro running about in 

 all its conspicuous arctic livery under the bright rays of 

 an April or May sun. After a few years such imported 

 liares, or more probably their offspring, ceased to turn 

 completely white, and the breed assumed the appearance 

 of the ordinary hares of the southern locality to which 

 they had been transported.' 



It would, of course, be extremely interesting to ascer- 

 tain whether such transported individuals ever do give 

 up the practice of turning white in winter, or whether 

 it is only their offspring that do so ; but, in any case, 

 it is clearly demonstrated that the habit is veiy deep 

 seated aud difficult to overcome. 



Very curious is the circumstance that the mode in 

 which the coat is changed in the variable hare at the 

 two seasons of the year differs in toto as regards the 

 parts of the animal first affected. On this subject, with 

 one verbal change in the first sentence, we may quote 

 from Dr. Allen, who writes as follows : — 



" In the fall the change begins with the feet and ears, 

 the sides of the nose and the front of the head, which 

 oft?n become radically changed before the body is much 

 affected ; while as regai'ds the body, the change begins 

 first at the base of the tail and extreme posterior part of 

 the back, and at the ventral border of the sides cA tjie 

 body, working thence upward towards the middle line 

 of the back, and from behind anteriorly, the crown of 

 the head aud a narrow median line over the shoulders 

 aud front part of the back being the parts last changed. 

 In the spring the order of change is exactly the reverse, 

 the moult beginning on the head and along the meliaii 

 line of the anterior half of the dorsal region, exton.Jing 

 laterally and gradually to the ventral border of the sides 

 of the body and posteriorly to the rumj:. and then later 

 to the ears and down the limbs to the feet, which are 

 the parts last affected, and which often remain but little 

 changed till the head and body have pretty completely 

 assumed the summer dress." 



It is very hard indeed to conjecture any satisfactory 

 reason for this remarkable difference. 



The American variable hare ranges, at ordinai-y levels, 

 about as far south as Massachusetts, that is to say, nearly 

 to the latitude of Madrid, and throughout the whole of 

 this extensive tract it turns white in winter. On the 

 other hand, owing to the much milder climate of 



