144 



The total number received from the spring was two hundred and 

 forty-two, of whicli but eight were found to have eaten anything (a 

 little over three per cent, of the whole), and these had taken only 

 Algse and vegetable fragments. 



An example of the water of the spring sent me contained many 

 Algae, but no animals larger than rotifers. The water of the hatch- 

 ery, being exposed in ponds of considerable size, afforded a better 

 opportunity for the development of animal life, to which fact was 

 doubtless due the occurrence of insect larvfe and Entomostraca in 

 the intestines of the fishes reared in it. The situation of the 

 sprmg, on the other hand, was particularly unfavorable, as it was 

 under the hatchery, and consequently in the dark. 



The observations above described on the specimens kept in spring 

 water, have but little value, for the reason that evidently very little 

 food was contained in the water fiowmg through their cage. The 

 vegetation in the streams being chiefly filamentous Algae, and the 

 number of Entomostraca apparently trivial, very little of either veg- 

 etable or animal food could reach the little prisoners. It is not 

 surprising, therefore, that notwithstanding their greater age and the 

 higher temperature of the water in which they were kept, a much 

 smaller ratio of the specimens had taken food than of those cap- 

 tured in the hatchery. From the contents .of their intestines we 

 ■can only infer that these fishes, reduced to a desperate strait by 

 starvation, will snatch at almost anything contained in the water. 

 The result obtained by a study of ttiose from the hatching house 

 was more significant, but still unsatisfactory. It seems to indicate 

 "that in confinement white-fish fry will feed upon both animal and 

 vegetable structures to some extent, and that they can be induced 

 to take minute fragments of the higher crustaceans, but not in suf- 

 iicient quantity to keep them alive. Tlie fact that animal food was 

 more abundant than vegetable in this last lot, indicates nothing of 

 their natural preference, since it was doubtless also more abundant 

 in the water containing them. 



More light was thrown upon the earliest food habits of these fishes 

 by the discovery of raptatorial teeth upon the lower jaw than by 

 these dissections of their alimentary canals. All the families of 

 fishes which I had previously studied whose young were provided 

 with teeth, were found strictly dependent at first upon Entomostraca 

 and the minuter insect larvae, while only those whose young were 

 toothless fed to any considerable extent upon other forms. The 

 discovery of teeth in the young white-fish, therefore, placed this 

 species definitely in the group of those carnivorous when young. 

 The fact that the adult was itself toothless interfered in ho way 

 with this inference, because other toothless fishes (Dorosoma) whose 

 young were furnished with teeth had been found carnivorous at an 

 early age. 



The inconclusive character of the results thus far obtained, made 

 it necessary to attempt to imitate more closely the natural condi- 

 tions of the young when hatched in the lake. In February, 1881. 

 I obtained, through the kindness of Mr. Clark, twenty-five speci- 

 mens of living young w^iite-fish, saved from a lot which he was 

 planting in the waters of Lake Michigan, ofi" Racine, Wisconsin. 



