nv 
American Fisheries Society. 147 
considerable amount of oxygen, nearly 8 cc. per liter; 8 parts 
per thousand of volume at the surface and about 7.5 at the depth 
of 18 meters. I may say that in the early part of the season, for 
convenience sake, we made our observations in the shallower 
0 IC 

Fic. 4—Lake Mendota, May 24, 1905. 
water near the University instead of going a mile or so further 
to the deeper water of the lake. But the story at this time would 
be the same in the deeper water, and this fact I have indicated 
by continuing the temperature and oxygen lines to the bottom 
of the diagram. In the early spring temperature and oxygen 
