48 ANIMAL ECOLOGY 



will enable one to work advantageously in many 

 localities (as in the state of Illinois). Of this num- 

 ber perhaps not more than about one half or one third 

 can be considered dominant. Every one who has 

 tried to make extensive local lists of species knows 

 that it requires many years of collecting to secure a 

 large number of species. These rare species are 

 generally of quite minor importance ecologically. 

 Considerations of this character should be encourag- 

 ing to those who may be intimidated by the idea of 

 large numbers of species. Then, of course, it should 

 be remembered that there are many aspects of eco- 

 logical work which do not meet with this variety of 

 animals. 



