102 
The First Food of the Common White-Fish. 
better opportunity for the development of animal life, to which 
fact was doubtless due the occurrence of insect larvae and Ento- 
mostraca in the intestines of the fishes reared in it. The situation 
of the spring, 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 flowing through their 
cage. The vegetation in the streams being chiefly filamentous 
Algae and the number of Entomostraca apparently trivial, very 
little of either vegetable 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 captured 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 con- 
tained in the water. The result obtained by a study of those from 
the hatching house was more significant, but still unsatisfactory. 
It seemed 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 sufficient quantity to keep them alive. 
The 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 fam- 
ilies 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 definately in the group of those car- 
nivorous when young. The fact that the adult was itself tooth- 
less interfered in no way with this inference, because other tooth- 
less fishes (Dojjsoma) whose young were furnished with teeth, had 
been found carnivorous at an early age. 
