216 THE BOOK OF NATURE STUDY 



should be watched, and it may be noted that they are all carniv- 

 orous and poisonous, unlike their distant allies the millipedes 

 which are vegetarian and non-poisonous. Underneath the 

 stones one will also find slugs and earthworms, burrowing beetles 

 and ants and other insects. 



The Mountain-side. In some parts of Britain an excursion 

 to the top of a high hill is much more feasible than one to the 

 seashore. The list of distinctive animals that one may hope to 

 see in climbing the hill will vary with the altitude and with the 

 degree of wildness. We must take a case in our own experience. 



A very interesting and distinctive frequenter of the mountains 

 is Lepus timidus, the variable or blue or mountain hare. A 

 characteristically northern animal, the only hare in Scandinavia 

 and Iceland, it lingers on mountain ranges like the Alps and 

 the Pyrenees. In colder countries in most of Scotland, but not 

 in Ireland it turns white in winter, except the tips of its ears, 

 which are always black. At the approach of winter there is a 

 new growth of white hairs, and the coloured hairs blanch. It 

 seems as if it were the cold that pulls the trigger of this constitu- 

 tional tendency to change, which probably has some utility, e.g. 

 in making the animals less conspicuous. The mountain hare has 

 no regular " form " like the common hare ; it hides among the 

 rocks and heather. 



Another mammal often seen on the mountains is the stoat 

 or ermine (Mustela erminea), which preys upon young hares, 

 grouse, ptarmigan, rats, voles, and so on. The mountain hare is 

 white in winter, except the black tips of its ears ; the ermine is 

 white except the black tip of its tail. On very high mountains 

 the white forms may be seen all the year round, on the low ground 

 the white form may never be seen at all. The white dress seems 

 to be due partly to a growth of new hairs with gas bubbles where 

 the pigment should be, and partly to a removal of pigment from 

 hairs which were pigmented. 



The other mammals that are likely to be seen on our hills are 

 the deer, the fox (who is rather a different creature from Reynard 

 of the plains), and the common shrew. 



A northern bird seen on some of the highest Scotch mountains 



