114 The Ohio Journal of Science [Vol. XXI, No. 4', 



Methods of Collection and Study. 



The fishes were caught in . a large fine-meshed seine and 

 placed immediately in a ten per cent solution of formalin, thus 

 preserving the stomachic and intestinal content and preventing 

 further digestive action. Collections were made at nearly 

 all hours of the day. An examination of the content of the 

 digestive tract was made with a compound microscope, the oil 

 immersion being necessary in many cases for a final determina- 

 tion of species. The technique of the work is very simple. A 

 longitudinal slit, made along the ventral side of the fish, exposes 

 the stomach and intestine, a small portion of which can then 

 be pinched ofiE and a microscopic mount made in the usual 

 way. Adult fishes are not included in this discussion, examina- 

 tion being limited to specimens 1.5 to 7.5 centimeters in length — 

 measured from the point of the snout to the base of the caudal 

 fin. 



Food and Feeding Habits — General. 



Since the excellent work of Forbes, nearly forty years ago, 

 on the freshwater fishes of the United States, very little study 

 has been made upon the nature of the food of the gizzard shad. 

 According to Forbes (3), the shad is a "mud lover par excellence'" ; 

 it swallows "large quantities of fine mud containing about 

 twenty per cent of minutely divided vegetable debris"; and it 

 consumes, when young, food that is approximately ninety per 

 cent microscopic animal organisms and the rest microscopic 

 plants. From data at hand it appears that these statements 

 require considerable modification when applied to young fish 

 within the limits of this study. 



Mud may form as much as thirty per cent of the contents 

 of the digestive tract, or it may be entirely lacking; in fact, in 

 those fishes taken from St. Mary's Lake it was quite impossible 

 to detect even the smallest quantity. A small portion of the 

 contents is unrecognizable plant debris. It appears that the 

 mud is merely incidental — so much unavoidable non-nutrient 

 material that goes in with the real food. No consideration is 

 given, therefore, to its varying amount in the digestive tract. 



The number of microscopic algal forms found in the stomach 

 and intestine of the gizzard shad is markedly large. If one can 

 conceive of all the different plankton forms of a given lake 



