146 Thirty-fifth Annual Meeting 
can find without going too far from our laboratory. The horizon- 
tal figures represent two things. They stand, in the case of tem- 
perature, for degrees centigrade, and, in the case of oxygen, they 
Dial Ope O 

TO 
F1G. 3—Lake Mendota, April 22. 1905. 
represent cubic centimeters of gas per liter of water; that is, 
parts per thousand in volume, of the gas in question. The line 
marked “Tl” represents the temperature in each diagram and the 
line marked “O,” the oxygen. 
In the latter part of April we find a temperature of about 
C. both at the top and bottom of the lake. There isa very 
90 
6 
