64 MOUNTAIN AND MOORLAND 



now occur in England. When glacial conditions pre- 

 vailed over Central Europe the Mountain Hare was 

 doubtless common in southern countries; when the 

 climate became milder it disappeared except from 

 mountain ranges, such as the Pyrenees. Its bones 

 have been found in England, but the country evidently 

 became too mild for this strenuous creature. It does 

 not differ greatly from the Common Hare, but it has 

 many small peculiarities, such as whiter flesh. It has 

 no particular resting-place or " form," but shifts from 

 one hiding-place to another among the rocks and 

 heather. It is often reduced in the winter to very 

 short commons, and has been seen nibbling the 

 lichens off the rocks. When the mountains are 

 covered deeply with snow it comes down to the 

 valleys. It shows the same kind of colour change as 

 the Ermine, and its garment of invisibility, as we have 

 called it, will help it on a background of snow to 

 escape the keen eyes of Eagles and Hawks, Ermines 

 and Foxes. An interesting little detail is that the 

 Mountain Hare changes to white all but the tips of 

 its ears, which are black all the year round, while the 

 Stoat changes to white all but the black tip of its 

 tail. The change from the yellowish-grey of sum- 

 mer to the white of winter is partly due to the growth 

 of new white hairs, but it has also been proved that 

 brown hairs may be changed into white ones. In the 

 American Hare it seems that the process of putting 

 on the white dress is always twofold a growth of 

 fresh hairs without pigment and with gas vacuoles, 

 and a slow blanching of previously pigmented hairs. 

 Thinking of the origin of this power of whitening 

 that the Ermine and the Mountain Hare show, we 



