A LIMNOLOGICAL RECONNAISSANCE 55 



bottom dwellers present at a particular time and the amount 

 of organic matter in them. The annual production involves 

 the j'early turn-over in the bottom population, and this ques- 

 tion includes such problems as the number of broods of 

 insect larvae annually, the rate of reproduction of the Oli- 

 gochaeta, and the extent of the depletion of this entire 

 population each year by being consumed as food and by 

 other causes. 



TABLE 27 — Obsei'S'ations on the bottom fauna of Okoboji lake, July 

 30 and 31, 1919. The first column for each depth shows 

 the number of individuals per square meter of bottom 

 and the second column gives the number of grams of dry 

 organic matter per square meter. 



