430 
The observed maximum (27.8° C.) is probably not the real maximum 
as no continuous series of summer temperatures was taken, and the diurnal 
change in temperature was very great during the variable periods of 
autumn and spring. The greatest observed variatien for twenty-four hours 
being 10° C. on Oct. 11-12. 
Temperature above 4° C. does not seem to affect the forms which are 
found in the pond throughout the year, {. e., beetles, Corethra lary, am- 
phibian larve, etc. Below this temperature, however, their activity is de- 
ereased and below 2° C. they are quite passive. For some time after the 
ice formed in the winter of 1909-1910, the Corethra larvze could be found 
in all parts of the pond. Amphibian jarvee came to the surface when the 
ice was cut, and the beetles could be seen crawling on the Typha stems be- 
neath the ice. On Jan. 11, 1910, the upper layers of water (three inches 
under the ice) had a tenmperature of 2.2° C. The lower layer (24 inches 
under the ice) was 3.1° C. There were few Corethra larvee in the upper 
layer and these were quite inactive. Near the bottom of the pond in the 
deepest part, they were present in great numbers and were much more 
active than those in the upper layers. Laryze from either region became 
more active when the temperature was raised. Many dead larvie were 
found just below the ice. It may be concluded then that a temperature be- 
low 4° C. reduces the activity of Corethra larvie. At 2° they become quite 
passive and temperature lower than 2° may prove fatal. 
Amphibian larvee were active and could be captured in quantity during 
December and most of January. On Feb. 1, 1910, the central, Typha free 
part of the pond was carefully dredged for amphibian larvee but none were 
captured. Holes were then cut in the ice nearer the margin of the pond. 
Two larvie were captured ten feet from the north end. These were in the 
r 
debris among the Typha stems. They were rarely captured until the ice 
disappeared in March. On March 3, the ice had disappeared and the larvze 
were much in evidence. The temperature just under the ice on Feb. 1 was 
8° C. and near the bottom was 2.8. 
It seems that the formation of ice on the surface does not cause a 
quiescent stage in amphibian Jlarvee but a temperature of about 2° C. does 
reduce their activity. It may be, in both these cases, that it is the con- 
tinued low temperature that causes these stages of inactivity. However, 
in the winter of 1908-1909, the water was not above 4° GC. from Dec. 2 to 
Jan. 27 and no period of inactivity was observed in these forms. 
