SUMMABY AND DISCUSSION I45 



Taking the entire lake into account the net plankton of Lake Waubesa 

 gave an average of slightly more than 81 kilograms of dry organic 

 matter per hectare of surface (72 pounds per acre) for the complete 

 series of catches; the range is from a minimum of 23 kilograms to a 

 maximum of 195 kilograms per hectare (20 pounds to 174 pounds per 

 acre). The average for the 16 catches corresponding to the nanno- 

 plankton is 80 kilograms per hectare, or a little more than 71 pounds 

 per acre. 



A comparison of the results for the deep portions of the three lakes 

 shows that the complete series of net catches from Lake Mendota yielded 

 an average of somewhat more than 73 kilograms of dry organic matter 

 per hectare, the series from Lake Monona a little more than 171 kilo- 

 grams, and that from Lake Waubesa approximately 170 kilograms. 

 Thus, the average amounts are substantially the same for Monona and 

 Waubesa, with a slight advantage in favor of the former, while the 

 average of Mendota is less than half as large as those of the other two 

 lakes. Table 1 shows that the maximum depth of Waubesa is slightly 

 less than half as much as the maxima of the other two lakes, yet it 

 maintains substantially as large an average crop of net plankton in the 

 deep water as Monona and a far larger amount than Mendota. Com- 

 puted on the basis of the entire volume and area of each lake the aver- 

 age amounts of dry organic matter in the standing crop of net plankton 

 per unit of surface are as follows, Mendota 42 kilograms per hectare 

 (37 pounds per acre), Monona 72 kilograms per hectare (64 pounds 

 per acre), Waubesa 81 kilograms per hectare (72 pounds per acre). 

 Thus, for the entire lake the standing crop of net plankton of Lake 

 Waubesa yields an average of almost twice as much organic matter 

 per unit of surface as that of Lake Mendota and 12.5 per cent more 

 than that of Lake Monona. 



It should be noted again that the series of net catches from Lakes 

 Monona and Waubesa cover only the period from late May to early 

 November in the different years, so that the averages may be higher 

 than they would be if catches had also been taken during the interval 

 extending from the middle of November to the middle of May. On the 

 other hand, it is shown on page 143 that the average for just those net 

 samples from Mendota which correspond in time to those taken on 

 Monona is about 8.0 per cent smaller than the average for the complete 

 series of net catches from Mendota. 



Lake Kegonsa. Only one sample of net plankton was obtained from 

 Lake Kegonsa and that contained 3,378 milligrams of dry organic mat- 

 ter per cubic meter of water. (Table 25). For the entire lake this 

 amount is equivalent to 174 kilograms per hectare (155 pounds per 

 acre). The percentage of nitrogen in this material is smaller than the 



