l6 INTRODUCTION TO PLANT GEOGRAPHY [CHAP. 



it is only secondarily that this in turn largely conditions the animal 

 population — which thus becomes a subordinate characteristic of the 

 locality and is usually less evident and immediately significant than 

 the vegetation, at least on land. Indeed, where there are no suitable 

 plants there can be no animals living normally. As M. D. Haviland 

 puts it in the work cited at the end of Chapter XVII, 



* It is the faithful correlation of plant growth with the physical environ- 

 ment, especially to the important factor, or complex of factors, called 

 " climate ", that leads us naturally to define the main types of land 

 environment in terms of plant life as Woodland, Grassland and Desert 

 . . . for vegetation is the apparel of scenery. As Darwin wrote : " A 

 traveller should be a botanist, for in all views plants form the chief 

 embellishment." But when the zoologist, forsaking botanical terms, 

 tries to classify environments in the language of his own science, he 

 cannot construct a workable scheme ... he finds that he must fall 

 back on the language of the botanist or geologist.' 



In general, zoologists have not been very successful in recognizing 

 definite animal communities of a complex nature, and their study 

 in individual species of adaptive response to particular environments 

 tends to be of less immediate significance than that of botanists 

 with plants. Thus, whereas the marked dwarfing of many arctic 

 and alpine plants is related directly to exposure to harsh physical 

 environments, many similarly striking animal characteristics, such 

 as broad teeth for grinding seeds and special organs for climbing 

 trees, are related to the climatic conditions only indirectly through 

 plant response. Nevertheless, as pointed out by Professor G. E. 

 Hutchinson {in litt.), there are a number of known cases of warm- 

 blooded animals responding directly to climate. For example, 

 boreal Mammals not only have under-fur but also are of larger 

 absolute size, and have shorter ears and tails, than their southern 

 counterparts, while almost all desert Mammals and Birds are pale 

 even if nocturnal, and insular races of Birds have relatively large 

 beaks and feet. But in spite of such exceptions, and others which 

 act in the opposite direction (such as the striking adaptations of 

 many flowers to insects in relation to pollination), plant response 

 to climate is usually direct whereas that of animals tends to be 

 indirect. Then again, animals are usually mobile, and individuals 

 may wander or migrate vast distances. Consequently, apart from 

 such connections as those mentioned above, animals tend to be of 

 less geographical significance than plants, in the sense that they do 



