Lake Maxinkuckee, Physical and Biological Survey 109 



greater variety than in the open lake and were often present in 

 much greater quantity. The latter seems to have been due to the 

 prevailing wind at the time. 



In the hauls made in daylight the greater portion of the plank- 

 ton was found in the upper 10 feet of water, with most of it 

 in the first three feet. In the hauls made during the night the ver- 

 tical distribution was somewhat different. There seemed to be a 

 downward migration of the surface plankton, so that while the 

 total quantity remained about the same, less of it was in the first 3 

 feet than during the daylight. During the earlier hours of day- 

 light it resumed its former distribution. Since the greater portion 

 of the plankton consisted of plant forms, the absence of the photo- 

 synthetic processes may have been the cause for this downward 

 migration. 



The total quantity of plankton reached its maximum the last 

 of July and the first of August. During the last of August the 

 quantity decreased very considerably, and the water became quite 

 clear. 



During July and the first half of August the prevailing plant 

 form was a species of Rivularia. A species of Anabsena was also 

 in abundance. During the latter part of August a species of 

 Lyngbya was the most abundant plant form. Until about the 

 tenth of August a number of entomostracans were found at a 

 depth of about 25 feet in the open lake, but at this time they dis- 

 appeared and could not be found in either deeper or shallower 

 water. 



No uniform difference in the vertical distribution and the total 

 quantity of the plankton at the various stations in the deeper water 

 was detected, except that at Station No. IV in 25 feet of water, the 

 entomostracans mentioned above were not found. The entomos- 

 tracans were not so abundant on the Sugarloaf as in water of 

 equal depth near the shore among the bulrushes. In the shallow 

 water, near the shore, there was often a greater quantity of plant 

 forms and always a greater quantity of animal forms than in 

 deeper water. The greater quantity of plant forms was due to 

 drifting by the wind. 



The quantity of plankton during this summer was less than 

 half that of the previous summer. The greater portion consisted 

 of plants during both seasons, but the prevailing form in 1899 

 was Lyngbya, while in 1900 it was Rivularia. No plankton ob- 

 servations were made in other lakes during this summer, but in 

 doing some sounding in Bass Lake, it was noticed that there was 

 very much more minute vegetation in Bass Lake than in Lake Max- 



