QUANTITY 



69 



We note that on the whole the carbonates, C0 2 , and bacteria are 

 greater in quantity according to age. Oxygen is on the whole less. 



TABLE VII 



Showing the Number of Entomostraca in Approximately 90 Liters of Water 



TABLE VIII 



Showing Ratio of Number or Quantity of Different Organisms When the 



Maximum Is 100 



Rooted vegetation 



Entomostraca 



Midge larvae .... 



Sphaeridae 



Gilled snails 



Lunged snafls. . . . 



Amphipoda 



Crayfishes 



Insects 



Fish 



Pond Numbers — Ecological Age-Series 



32 

 80 

 O 

 20 

 IO 



50 



IO 



40 



IOO 



60 



35 

 So 



50 

 50 

 50 

 go 



50 

 00 

 87 



146 



100 

 100 



IOO 

 IOO 

 IOO 

 IOO 

 IOO 

 IOO 

 IOO 



87 



The Entomostraca are rated on the basis of actual count of six col- 

 lections. The other figures are estimates (6). 



Here we note that the number of Entomostraca was greater in the 

 older ponds though some irregularities occur, dependent upon the 

 amount of rainfall. In rainy seasons the increase with age appears 

 almost throughout. 



As we pass from younger to older ponds we note an increase in the 

 number of animals, excepting fish. These appear to decrease, probably 



