98 The First Food of the Comtnon 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 

 larvaj. When that paper was prepared, I had, however, no oppor- 

 tunity to study the food of the young of any members of the family 

 Salmonidge, 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 Algae ; 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 food, 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 with 

 bread crumbs, and the fish were seen to take small particles in 



*Report of the U. S. Fish Commission for 1872-3, pp. 44-46, 



