Birge and Juday—Development of Cyclops . 7 
Cocoons were also found in several other lakes, as listed in 
the table below: 
Date 
Depth, m. 
Temp., C. 
O, cc. per. 
1. 
Rainbow. 
June 29, 
1907 
27.0 
5.6° 
0.12 
Kawaguesaga.. 
Sept. 6, 
1906 
17.0 
11.3° 
0.0 
Kawaguesaga... 
Aug. 5, 
1907 
17.0 
8.1° 
0.0 
Black Oak. 
Aug. 14, 
1907 
24.5 
5.2° 
0.6 
Thousand Island. 
Aug. 13, 
1907 
21.5 
4.7° 
0.5 
Long (New Auburn).... 
Aug. 29, 
1907 
23.0 
8.7° 
0.2 
Kawaguesaga Lake is of the same type as Lake Mendota, 
the bottom water losing its oxygen in summer. Black Oak, 
Thousand Island and Long lakes have abundant oxygen in the 
cold water, and there can be no such direct cause for encysta- 
tion as appears to exist in Mendota. 
The case of B-ainbow Lake is very interesting. It is one 
of the Chain of Lakes, Waupaca, having an area of about 100 
hectares (243 acres) and a maximum depth of about 29 meters 
(95.1 feet). The following table show r s the condition of the 
lake as regards temperature and oxygen. In September the 
lower water is practically uninhabitable, though there is still 
a thin stratum of cool water above 10 meters, which contains 
abundant oxygen. In June, when the cocoons were found, 
there was abundance of oxygen in the cool water. 
Depth, m. 
June 29, 1907. 
September 10, 1907. 
Temp. 
O, cc. per 1. 
Temp. 
O, cc.perl. 
0. 
22.6° 
5.8 
18.8° 
0.1 
10. 
10.0° 
5.7 
10.5° 
0.15 
15. 
6.5° 
4.5 
7.0° 
0.25 
20. 
5.9° 
2.2 
6.3° 
0.02 
25. 
5.7° 
0.6 
6.0° 
0.0 
27. 
5.6° 
0.12 
5.9° 
0.0 
It is plain that there is here no obvious direct cause for en- 
cystation. Still further, Marsh ( ? 03, p. 27) places Rainbow Lake 
in his list of <e pulchellus (i. e. bicuspidatus) lakes,” in which 
