98 
The First Food of the Common White-Fish. 
which they feed should be carefully determined, and that each 
locality where the young are deposited should be closely searched 
for the purpose of ascertaining whether their food species occur 
there at the time in sufficient quantity to prevent immediate star- 
vation. 
Previous studies of the food of young fishes of a variety of fam- 
ilies, reported in the third Bulletin of this series, had showed that, 
with exceptions presently to be mentioned, the earliest food of all 
the families studied consisted almost wholly of various species of 
Entomostraca and some equally minute and delicate dipterous 
larvae. When that paper was prepared, I had, however, no oppor- 
tunity to study the food of the young of any members of the family 
Salmonidae, to which the white-fish belongs, neither could I learn 
that any such studies had been made by others; and I could only 
infer the same fact with regard to this family from the general 
character of the results obtained by the study of the other groups. 
Even this inference, however, was rendered doubtful by the dis- 
covery that the youngest individuals of two of the toothless fami- 
lies (Catostomidae and Cyprinidse) were not strictly dependent 
upon the food elements above mentioned, but were likewise able 
to draw upon much smaller organisms, namely: the minutest 
Protozoa and unicellular Alga3; and as the adult white-fish is like- 
wise destitute of teeth, it was not by any means certain that their 
young would not fall under the latter category. Upon looking up 
the literature of the subject, I found that although the food of 
the adult had been very well made out in a general way,'* only 
two items had been published respecting the food of the young. 
In the report of the United States Fish Commission for 1872-3,“ 
an assistant commissioner, Mr. J. W. Milner, made some experi- 
ments on young white-fish hatched artificially, supplying them 
with a number of articles of foody in the hope of finding some- 
thing suitable for their nourishment. 
“A few crawfish,” he says, “were procured and pounded to a 
paste, and small portions put into jar No. 1; the young fish ate 
it readily. They were fed at night, and the next morning every 
one of them was found to be dead. Jar No. 2 was supplied witli 
breads crumbs, and the fish were seen to take small particles in 
^Report of the U. S. Fish Commission for 1872-3, pp. 44-46, 
