ANNUAL DISTRIBUTION OF THE ORGANISMS. tf 



The collections of Glolotrichia in the other lakes of the state 

 were made on only a few dates so that a comparison of num- 

 bers would be subject to revision after a more complete knowl- 

 edge of those lakes. So far as appears, however, Gloiotrichia 

 occurs in vastly greater abundance in Lake Winnebago than in 

 the other bodies of water from which collections were made. 



The only exception to this was a very large collection of 

 Gloiotrichia made on Pelican lake August 12, 1902. Other 

 collections made on Pelican lake in preceding years, however, 

 did not indicate SO' large a production of this plant as in Lake 

 Winnebago. 



Sphaerella lacustris (Girod) Wittrock. 



This organism I have found a fairly constant constituent of 

 the plankton of Green lake. During the first year it occurred 

 in the collections from September until the next June. Dur- 

 ing the second year it was found from early in August until the 

 last of December. In the third year it appeared through the 

 fall months, and after that the collections were discontinued. 

 Its maximum of appearance seems to be from September to 

 January. In Green lake it seems to be distinctly characteristic 

 of the cold season. 



I have not found this form in Lake Winnebago, but it does 

 occur in a number of the other lakes, generally in small num- 

 bers, but in August, 1900, I found large numbers in Shawano 

 and Pelican lakes. 



Although it is found in the plankton more in the colder sea- 

 son, it does not follow that it lives in Green lake only at that 

 time, for I have found it in enormous numbers in Dartford Bay 

 in boats that were standing half full of water in the summer. 



Dinobryon. 



Dinobryon occurs in both Green lake and Lake Winnebago. 



In Green lake the largest collections have been in May, June, 

 and July, but it may occur in any month. 



In Lake Winnebago I have never found it in July and Au- 

 gust, but it comes in with September, is found in small numbers 

 3 



