HOW ARCTIC ANIMALS TURN WHITE 65 



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

 often become radically changed before the body is much 

 affected; while as regards 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 of the 

 body, working thence upward towards the middle line of 

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

 head and a narrow median line over the shoulders and 

 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 median line 

 of the anterior half of the dorsal region, extending laterally 

 and gradually to the ventral border of the sides of the 

 body and posteriorly to the rump, 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 ordinary 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 Western Europe, 

 no colour-change takes place in the mountain hares of 

 Ireland, while it is reported that in those introduced into 

 Ayrshire and the neighbouring counties of south-western 

 Scotland the change is much less complete and regular 

 than in those inhabiting the northern parts of the 

 country. 



An impression appears to be prevalent that in the more 

 northern portion of their range both the mountain hare and 



5 



