28 THE UNIVERSITY SCIENCE BULLETIN. 



the result that the Corixids came to occupy the added forage 

 grounds in this shallower water, for Corixids are lovers of shoal 

 waters and adapt themselves in time to the oscillations of the 

 pond in which they live. The species of boatmen studied pos- 

 sessed no functional wings and must as a rule be bound to 

 permanent water. But permanent water does not imply that 

 the life within is not subject to varying fortunes and conditions 

 as shown in the notes on Bool's Backwater. For this pool 

 would be threatened with unsightly patches of filamentous algae 

 during extended dry hot weather, but be cleansed again with 

 the next rains. And these factors enter into the life of the 

 organisms within its waters. 



INTERRELATIONS WITHIN THE POOL. 



When one undertakes to study the adjustments of any one 

 set of organisms to each other he finds the field restricted and 

 unknown on every hand. He may pursue disturbing factors 

 into other groups only to find these factors held in balance by 

 still other causes, and so ad infinitum. Not an organism of 

 the pool can escape the influence of its fellows, and no final 

 analysis can be reached till all are understood. 



The pool is indeed a restricted environment and yet only the 

 more obvious facts are known concerning the life within it. 



In Introducing, therefore, a few ecological notes relating to 

 the water bugs the writer has not the temerity to claim more 

 than a designation of the more apparent features. These are 

 considered briefly in the following outline : 



a. Haunts and Habits. 



b. Habitat Key. 



c. Relation to other organisms. 



1. Parasitism. 



2. Oviposition. 



3. Feeding habits. 



While the relation of the water bugs to other organisms is 

 largely a question of feeding habits, it is well to consider first 

 of all the relative location of each form. Haunts and habits 

 determine in large measure the range of influence of each unit 

 in the environment. 



In another chapter the families of water bugs are enumer- 

 ated. There are thirteen of them. Four are limited in large 

 measure to the moist shores adjacent to the water. Two live 

 upon the rafts of algse and other vegetation floating out from 



