24 ANIMAL ECOLOGY 



of the usual character are of great importance, and 

 with students of taxonomic training and interests 

 only, this form of survey occurs very naturally. 

 Most of the governmental and state surveys and 

 museum expeditions are developed along these 

 lines. The frequency with which such methods are 

 used in surveys, which are expected to produce 

 economic results, indicates that these methods are 

 generally considered the most satisfactory. The 

 exceptions to this rule are mainly surveys of fresh 

 and salt waters, and are related in some way to 

 aquatic resources. Except when detailed individual 

 studies of certain species or some special subject 

 has been made, the usual form of the reports of such 

 surveys is the annotated list. It is rarely that even 

 brief chapters discuss the groupings of the animals 

 as they are found associated in nature. These 

 statements show that, judging from the past, the 

 methods currently used cannot be depended upon 

 for a rapid and symmetrical development of 

 ecology, or for the best development of ecological 

 surveys. These must be developed in a more direct 

 and deliberate manner, by carefully planned and 

 executed ecological investigations. It is desirable 

 also that ecological surveys should be conducted 

 along some one of the three main avenues of ap- 

 proach, individual, aggregate, and associational, in 

 order that the science may develop symmetrically. 

 The following are some of the reasons which may 

 be mentioned in favor of such surveys : 



As a record of the associations, their interrelations 



