239 



(a) A few well-known facts are emphasized, the variableness of the atmos- 

 phere and the persistence of the water; that water is a poor (b) radiator and an 

 indifferent conductor of heat, and responds slowly to atmospheric changes. 



(d) It shows also that the great volume of Syracuse lake at no time has been 

 stagnant, but that a condition of activity has obtained throughout the' entire period 

 of observation. 



(c) For the four months in which a large number of observations were made 

 the general average of the water, both surface and bottom, is higher than that of 

 the air. 



A difference of 10° between the water one foot deep near the shore and the 

 surface mid-lake during a rain the day the ice left the lake, shows that the surface 

 drainage is no small factor in winter and spring in raising the temperature of 

 the whole body. 



PART II. THE INHABITANTS OF TURKEY LAKE.* 



Plankton. 



By plankton, Hensen, the author of the word, means everything floating in 

 the sea and passively driven about by the waves and currents. Haeckel in- 

 cludes under plankton all organisms swimming in the sea. Haeckel says : 

 "The totality of the swimming and floating population of the fresh water 

 may be called limnoplankton." Limno'planktonic studies have been made when- 

 ever a collector scooped for protozoa, diatoms or other minute organisms. 

 Planktonic studies of this sort have been carried on for a long time. Recently 

 plankton has been studied in a new way, first in the ocean and more recently in 

 fresh water. This more recent study has been the quantitative and qualitative 

 estimation of the plankton in a given volume of water. There seem to have 

 developed in a remarkably short time two schools of planktonists, the one headed 

 by Hensen asserting that planktonic organisms are uniformly distributed, the 

 other, headed by Haeckel, being equally sure that planktonic creatures are to be 

 found in clouds or schools. We are interested in plankton only in so far as it is 

 part of the environment of the vertebrates inhabiting the lake. That it is not an 

 unimportant element of the environment is due to the fact that it forms the 

 primitive food of most of the fishes and that at the most plastic period in the life 

 of the individual. The amount of plankton, as well as its composition from year 



•Contributions from the Zoological Laboratory of the Indiana University, No. 16. 



