79 



during the month of August, and heavy rains often raised the surface of 

 the lake several inches above its normal level. The winds, which were gen- 

 erally accompanied by cloudy weather, blew the surface of the water into 

 waves of considerable magnitude for a small lake, and caused a piling up 

 of the surface water on the leeward side. Detailed records cannot be given 

 because the only anemometer available was adapted to winds of low veloc- 

 ity only, which rendered it useless during the high winds which prevailed. 



Dissolved Gases. 



A study of the dissolved gases revealed the fact that there was suffici- 

 ent carbon dioxide present for photosynthesis, and that oxygen was pres- 

 ent in sufficient quantities to support animal life at all depths. At the 

 surface of the lake there were 5 c. c. of dissolved oxygen per liter ; in the 

 upper layer of the epilimnion there were 4.2.5 c. c. present ; in the middle 

 of the thermocliue 2.35 c. c, and at the I)ottom of the lake there was 1.5 

 c. c. of dissolved oxygen per liter of water. 



The carbon dioxide increased from .8 c. c. at the surface to 8.75 c. c. at 

 the bottom. It increased from 2.5 c. c. to 5.5 c. c. from the top to the bot- 

 tom of the thermocline. 



METHOD USED IX PLANKTON CATCHES. 



Six stations, position of which are indicated on the outline map, were 

 established. They were located in positions which best showed the effect 

 of the wind upon the plankton. The depths of the staions varied from 

 7.5 to 23 m. The catches for this report wei'e mostly made at Station 1, 

 depth 23 m., the other stations being used as a check upon the results ob- 

 tained at that station. Weekly catches were made by the use of a brass 

 pump, known in the trade as "The Barnes Hydroject Pump," a three- 

 fourths inch garden hose, and a plankton net, the straining part of which 

 was made of No. 20 Dufour bolting cloth. These weekly catches were 

 taken I'espectively at the surface, 1 m., 2 m., 4 m., 6 m., 8 m., 10 m., 14 m., 

 20 m., and 23 m. The quantity of water, 10.4 liters, strained for each catch, 

 was the amount produced by 50 strokes of the pump. The ordinary count- 

 ing method was used to determine the number of organisms. In most cases 

 20 per cent, of the material was counted, but all individuals of forms read- 

 ily recognized by the naked eye were counted. 



