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ESSENTIALS OF ZOOLOGY 



Animal Populations 



A great deal can be learned about the relations of organisms by 

 quantitative methods making possible an estimate of the numbers 

 of various species present in a given community at any one time. 



Fig. 201. — Numbers of insects collected in average catch with 100 sweeps of 

 an insect sweep net in a prairie ravine (Oklahoma) arranged according to orders 

 through the season of the year. (Data from Carpenter.) 



Comparisons may then be made between the populations of com- 

 munities differing in some observable respect, or between the popu- 

 lation of the same community at different times of the year. It is 

 comparatively easy, although somewhat tedious, to determine the 



