22 Wisconsin Academy of Sciences, Arts and Letters . 
In conclusion, then, it may be said that the amount of dis¬ 
solved oxygen in the lower water of any lake determines wheth¬ 
er fishes that require cool water during the summer can or can¬ 
not thrive in a lake, and it also determines the vertical distri¬ 
bution in a lake of fishes that are able to occupy either warm 
or cool water. 
