American Fisheries Socvety. 157 
Green Lake is the only lake in Southern Wisconsin in which 
an oxygen curve of this character could be drawn. In most lakes 
the bottom water is practically devoid of oxygen in September. 
In Lake Mendota the whole of the cooler bottom water be- 
comes oxygen-free at a comparatively early period of the sum- 
mer and there is a long period there when the lower water can- 
not be utilized by animals. If this statement were true of all 
lakes, the smaller lakes would have only a very shallow surface 
stratum which could be utilized. But in many smaller lakes an 
operation goes on which materially increases the amount of oxy- 
een and the thickness of the stratum of water which is in- 
habited by animal life. Figure 9 shows the distribution of oxy- 
gen found on August 16 in Beasley Lake. 


Fic. 10—Beasley Lake. Aug. 16, 1905. 
Beasley Lake is a little lake about one-quarter of a mile long 
and half as wide, a kettle-hole, one of a chain of lakes at Wau- 
paca, in central Wisconsin, and one which shows, by the way, 
about as low bottom temperatures as any Wisconsin lake. You 
will notice that the temperature of the water begins to fall at a 
depth of 4 meters, or only about 13 feet below the surface. You 
will see also that the oxygen curve does not follow the tempera- 
ture curve as it does in Lake Mendota, but that instead of de- 
creasing the oxygen increases in the cooler water, so that at a 
depth of 6 meters there is a very large amount—11.2 cc. per 
liter. At 8 meters there is still as much as at the surface but 
