330 THE AMERICAN NATURALIST [Vol. LII 



throughout the year and actively forms buds in January, 

 February and March in the Adirondack waters. Micro- 

 scopic sections of these hydra taken in February reveal 

 the presence of minute Entomostracans in the enteron. 

 Some of these minute Crustaceans taken from a jar con- 

 taining the hydra were submitted to Dr. C. D. Marsh for 

 identification. He reported that they were Cyclops 

 americana. As cyclops is the common food of hydra we 

 may assume that this species, which is very abundant, is 

 eaten by these red hydra. At any rate, hydra feed on 

 minute animals so that animal food is a prerequisite for 

 their active growth. 



The food of the cyclops in turn is the minute floating 

 algal plants. These must be in relative abundance in 

 order to support so many of the minute Entomostracans. 

 Thus the conclusive proof of the active, reproductive 

 habit of these red hydra throughout the winter estab- 

 lishes the winter active life of cyclops and unicellular algae 

 in Little Lake Clear. 



These observations indicate a greater amount of vital 

 activity in such cold regions as the Adirondaeks than we 

 had been led to believe existed. If these minute and 

 simple forms of life live throughout the winter in an 

 active state, we may safely predict that most of the other 

 forms of life except the larger plants are also active and 

 that the winter food of fishes is probably similar to that 

 of the summer in many particulars. 



During the summer of 1916, I had opportunity to ob- 

 serve the habits of the red hydra which are common in 

 Lake Clear, particularly at station 12. A number of col- 

 lections were made early in the summer and I attempted 

 to bring some of the live animals back to the university, 

 but in each instance the hydra died before reaching the 

 city. I then tried to acclimate them to aquarium life, 

 placing them in regular aquaria jars in the boathouse, but 

 in each case the hydra died in from twenty-four to forty- 

 eight hours after being taken from the lake. As they 

 were kept in the lake water, the only explanation that 



