338 THE AMEBIC AN NATURALIST [Vol. LII 



while in Douglas Lake, Michigan, and Oneida Lake, New 

 York, molluscs are the more important. In Lake Clear, 

 cyclops and daphnia may be said to be their main food. 

 These two animals happen to be almost the only food of 

 the whitefish. The pumpkin seeds in Lake Clear thus be- 

 come a hindrance in the stocking of this lake. The num- 

 ber of pumpkin seeds eaten by other fish does not appear 

 to be large. It is suggested that food fish which live har- 

 moniously with whitefish but feed upon pumpkin seeds 

 would make a valuable combination. 



Forbes (pp. 108, 1883) made numerous experiments to 

 determine the natural food of young whitefish. He found 

 that cyclops were more important than all the other or- 

 ganisms combined. Hankinson (p. 239, 1914) also noted 

 the almost exclusive diet of cyclops and daphnia. Baker 

 (pp. 159-161) shows that not only Crustacea, but molluscs 

 are important as food for adult whitefish. My observa- 

 tions emphasize the limited diet of large whitefish in Lake 

 Clear where cyclops and daphnia are all that are eaten 

 during the summer. In the fall some specimens were 

 taken with the snail Amnicola in the stomach, but this 

 snail is present in limited numbers only, so can not be 

 very important as a source of food in Lake Clear. Dur- 

 ing the fall, small pumpkin seeds and their own eggs are 

 added to the daphnia-cyclops diet. It is to be noted that 

 all of the dead whitefish were in good condition, most of 

 them being fat. These all fed upon the daphnia-cvclops 

 diet. 



These cladocerans produce winter eggs in large num- 

 bers which are not destroyed by the digestive juices of the 

 whitefish nor the other fish that feed upon them. These 

 eggs pass through the entire digestive canal uninjured. 

 This is an important factor in keeping up the number of 

 these minute organisms. Were these winter eggs di- 

 gested and used as food, it is probable that this, the most 

 important source of food for whitefish, would soon become 

 exhausted. 



The brook trout taken in Trout Brook or at its mouth 



