ANNUAL DISTRIBUTION OF THE ORGANISMS. 43 



must be mucli less favorable in Lake Winnebago in winter than 

 in Green lake. I Lave very little to offer in the way of proof 

 of this suggestion ; it is significant, however, that the only other 

 lake from which I have winter collections, — Cedar lake, Wash- 

 ington Co., — has an amount of plankton intermediate between 

 Green lake and Lake Winnebago. Because of its smialler size 

 Cedar lake must be earlier than Green lake in freezing over, 

 and bcause of its greater depth, — nearly 100 feet, — the amount 

 of water as compared with its area is much larger than in Lake 

 Winnebago, and we might expect a larger production of plank- 

 ton than in that lake. 



COMPARISON WITH THE PLANKTON OF OTHEB LAKES. 



The other lakes connected with the Fox river, namely Lake 

 Poygan, Lake Wineconne, and Lake Buttes des Morts, resemble 

 Lake Winnebago very closely in the plankton, but the amount 

 is not so great. Of the other lakes, Pelican and Shawano were 

 particularly rich in plankton. Shawano, at the time of one set 

 of collections, had more plankton than Lake Winnebago. Peli- 

 can, in three of the four years in which examinations were made, 

 was considerably richer than Lake Winnebago. Both Shawano 

 and Pelican are shallow lakes and comparable with Lake Win- 

 nebago in their general characteristics. Sand lake in 1899 had 

 about the same amount of plankton as Pelican, but much less 

 in the three succeeding years. Stone, Birch, Cedar, and the 

 Waupaca lakes may, in a general way, be classed together, all 

 having considerably less plankton than the shallower lakes. 



The Eagle River lakes are connected by wide thoroughfares 

 so that they resemble each other very closely, but the larger ones 

 seem to have the greater amount of plankton. The same thing 

 is true of the Waupaca chain of lakes. 



In the case of the large collections which were made in all 

 these lakes, it was the plants also that formed the prominent 

 part of the plankton. 



In Table III have been listed the volumes of plankton as ob- 



