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 
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