302 FISH CULTURE. 
» 
gentle flow of water through it, and covered with a layer 
of gravel; the whole covered in by a lid. The eggs are 
deposited in the gravel or sand, and a stream of water, an 
inch or two deep, led through the trough. 
At the French Piscicultural establishment at Hunin- 
gue, and at the Stormontfield salmon-breeding ponds, 
the hatching apparatus consists of a series of horizontal 
troughs, arranged side by side like the steps of a stair- 
way, through which a stream of water falls in succession 
from the uppermost. 
After the eggs are deposited in the hatching-boxes, a 
proper supply. of pure water must be kept up until they 
hatch. They must be frequently examined to remove 
diseased eggs, and guard against the collection of sedi- 
ment. It is better that they be kept in darkness, for 
light encourages the growth of a parasitic fungus. 
When trout hatch they have still a large portion of the 
egg attached to the abdomen; this is endially absorbed, 
and while it remains they-require no food. It is the 
“yolk-sack.” Upon its complete absorption the young 
trout begins to feed, and must be placed where he can 
find his own food, or must be regularly supplied with 
such as is adapted to his infantile condition, and wi 
attract his attention, and tempt his appetite. 
The whole process of producing fish, by artificial im- 
pregnation and incubation, is in practice remarkably suc- 
cessful. More than.ninety per cent. of the eggs become 
living fish. Mr. Ainsworth, the authority quoted above, 
has this year obtained twenty thousand trout from twenty- 
one thousand eggs, being more than ninety-five per cent. 
In another point of view this process is of vast impor- 
‘tance. It facilitates the transportation of species from one 
* water to another. Salmon eggs, fecundated, were carried 
