40 THE ECOLOGY OF ANIMALS 



Buxton summarizes recent work on measurement 

 and control of moisture. Corresponding methods 

 have been developed for the study of aquatic con- 

 ditions, and these have been summarized for fresh 

 water by Chapman (1931). The science of hmnology 

 — the ecology of lakes — would require a volume to 

 itself. It has received very great attention in Europe 

 and in the United States. Work on this subject in 

 Britain has now become centralized in the laboratory 

 of the Freshwater Biological Association on Winder- 

 mere. 



We pass from this aspect of the problem, which 

 largely concerns methods and contains only a few 

 generahzations of importance in animal ecology, to 

 the next point — the necessity of defining as accur- 

 ately as possible the conditions under which animal 

 communities actually hve. A competent ecological 

 survey attempts to record as fully as possible the 

 general climatic data, geological and soil conditions, 

 vegetation, with full lists of all plants, together with 

 special notes on local variations. At the same time, 

 it is necessary to run continuous observations by 

 means of thermographs and other such instruments, 

 to get an exact picture of the fluctuations in chmate 

 during day and night and at different times of year. 

 The same applies to the vegetation, which will usually 

 show important seasonal changes. We begin here 

 to see that the habitat is not to be expressed i n 

 flvef?i.ges hut in tprms of the fluctuations t hat it 

 (iispla^:s,__which will in turn be of great importance 

 in showing limits, both in normal and abnormal 

 years. The importance of such habitat records for 

 all ecological surveys is that they enable comparisons 

 to be made between similar communities in different 

 regions, and between different communities in the 

 same region. At the same time, such records soon 

 acquire a historical value, as ecological succession 

 and other factors bring about changes in the habitat, 

 and with them changes in the animals. By the 



