20 THE TUNDRA AND ITS FAUNA 



whortleberries, &c., again forming an important part of 

 the available food supply. Again, as in the case of the 

 Swiss alps (p. 74), the vegetative growth of the plants 

 is checked by the natural conditions, and thus, though 

 stunted in appearance, they are relatively rich in 

 proteids and fats, and relatively poor in cellulose, which 

 makes their nutritive value high. With all that can 

 be said, however, the land offers but little food, and 

 the vast majority of the tundra animals depend partly 

 or wholly upon the sea, and are therefore necessarily 

 confined in their distribution to the margin of the sea. 

 The German expedition to Greenland made large 

 collections of both birds and mammals, and observed 

 the habits of all as closely as possible, and the conclu- 

 sion arrived at is that only four of the mammals can 

 be said to be permanently dependent upon the land 

 for food ; these four being the reindeer, the musk-ox, 

 the Arctic hare, and the lemming. Of the many birds 

 known to visit Greenland, only two can be said to be 

 at once permanent residents and wholly dependent 

 upon the land for food. These are the redpoll {Linota 

 hornemanni) and the ptarmigan (Lagopiis hyperboreiie). 

 All other birds and mammals are either partially 

 migratory or depend to some extent at least upon the 

 harvest of the sea. Even of the land plants the last 

 statement is partly true, for it is said that the phanero- 

 gams are especially abundant about the breeding-places 

 of the sea birds, on ground enriched by their dfoppings, 

 and such birds feed in the sea. Again, even of the four 

 mammals named, the reindeer, according to Norden- 

 skiold, does not disdain seaweed in times of scarcity. 

 Everywhere over the globe animals depend ultimately 

 upon plants, which alone can fix inorganic matter 

 in organic form, but it may be said to be the special 



