108 Lake Maxinkuckee, Physical and Biological Survey 



Ilyocryptus spinifer Herrick, Alona guttata Sars, and Leptodora 

 hyalina Lilljeborg. 



During the summer of 1900, plankton work on the lake was con- 

 tinued under the immediate direction of Mr. Leonard Young, along 

 the same lines and with the same apparatus used in the previous 

 summer. The work extended from the middle of July until the 

 first of September. 



Hauls were made from four stations. Three of these (Nos. 

 I, II, and IV) were the stations of the previous summer's work. A 

 fourth (No. Ill) was located on a line between Nos. I and II in 40 

 feet of water and on the rim of the deep basin of the northern part 

 of the lake in which No. I was located. No. Ill is separated from 

 No. II by a ridge (10 feet of water). At these stations hauls 

 were made from 3, 9, 15, 25, 40, and 80 feet, according to the 

 depth of the water. Random hauls were made along the shores 

 near the patches of bulrushes and among them, and also on the 

 Sugarloaf. The Sugarloaf is a small area of shallow water on 

 the northwest side of the deep basin of Station No. I. It is about 

 80 feet in diameter, in water with a minimum depth of 8 to 9 feet, 

 but surrounded by much deeper water. On the surface of the 

 mound are beds of Potamogeton, Chara, Nitella, etc. 



The temperature of the water at Station No. I was taken at in- 

 tervals of 5 feet at the time of each observation, except those made 

 during the night. The temperature of No. II in the Kettle-hole 

 was taken occasionally for comparison. The temperature of the 

 bottom was found to be slightly higher (l-2) than in the deeper 

 basin, although it was somewhat lower the summer before. Hauls 

 were made at various times during daylight hours, and also at 

 night, both before and after midnight. 



The plankton was examined from time to time, in order to de- 

 termine the prevailing forms composing it. The plant forms noted 

 were: Rivularia, Lyngbya, Anaba^na, Pediastrum, Protococcus 

 forms, (Edogonium, Spirogyra, Draparnaldia, and Raphidium. The 

 animal forms were Daphnia, Cyclops, Diaptomus, Rotifera, Vorti- 

 cella, and other unknown Protozoa and Crustacea. 



In the upper layers of the water in the open lake, the plankton 

 consisted almost entirely of plant forms. At a depth of about 25 

 feet a number of entomostracans were found, a species of Daph- 

 nia being the most abundant. These remained at that depth until 

 they disappeared later in the season. In the hauls made near the 

 shore and among the rushes, the animal forms were much more 

 numerous than in the surface water in the open lake and were 

 present in greater abundance. The plant forms here were in 



