680 AMERICAN ANGLER'S BOOK. 



other hand, by a gentle pressure downwards, exudes the eggs, which fall 

 into the shallow water in the vessel, and the fish is then returned to the 

 pond, that its remaining ova or milt may also become sufficiently mature 

 to have the operation repeated in the course of a few days. Pausing here, 

 the observer will perceive that the egg is nearly but not quite filled with 

 a yolk, the residue consisting of an air-chamber which, on the sinking of 

 the egg in the water, by reason of the greater gravity of the yolk, is 

 uppermost, and in the shell of the egg covering this cavity there is barely 

 perceptible, with the aid of a glass, a small orifice or hole. Resuming the 

 process, the operator takes from the vessel containing the fish, the males 

 already caught for that purpose, and, by manipulation like that applied 

 to the female, exudes the milt. The milt, which has about the color and 

 consistence of cow's milk, flows into the water containing the eggs. The 

 water is then greatly agitated, and, by the aid of a glass, innumerable 

 threads or filaments, projecting themselves from the mass of the milt, are 

 seen trembling and oscillating in the water, which, as the water settles 

 down, are observed to find their way to and into the air-chambers of the 

 eggs, through the little orifices already described.* 



Incubation. — The vessel containing the eggs, having been allowed to 

 remain for a few minutes, to make sure of perfect impregnation, is taken 

 to the hatching-troughs above, into which the eggs are transferred, where 

 they remain during the period of incubation. They are gently spread 

 over the gravel in the bottom of the hatching-troughs, and are kept in 

 contact with the water which flows in a gentle current over them. In the 

 course of a week or ten days, perhaps a few of the eggs will be observed 

 to have turned from a blackish salmon to a whitish color. This indicates 

 that perfect impregnation has not taken place, and that the egg is decay- 

 ing ; and with forceps provided for that purpose, it is simply removed from 

 the trough. Perhaps, too, some of the eggs will be found to have turned 

 to a rusty brown color. This is to be attributed to the presence of a species 

 of fungus, called hyssus, tak«n up, doubtless, from the water. It is destruc- 

 tive of the life of the egg, and as it grows and propagates itself (as sup- 

 posed), entire safety can only be attained by sacrificing every egg in 

 contact with it. These are the principal accidents to be looked for and 

 guarded against during the process of incubation : otherwise the piscicul- 

 turer, with even less care and skill than are required to operate the 



* This phenomenon, if it has ever been observed by European experimenters, I 

 have never seen recorded. Some remarks by a brother angler, bearing on the 

 discovery, will be found at the end of this article. 



