FISH CULTURE. 299 
and was hardly practised except in laboratories, when it 
was re-discovered in France a few years ago, under cir- 
cumstances that brought its economic bearing -promi- 
nently before the attention of learned men. 
Since the operation of extruding the eggs and milt is 
essentially mechanical, it can be as well performed by 
man as by the fish, and, once extruded, the milt performs 
its own office upon the eggs, and fertilizes them, with no 
other interference than suffices to bring them into con- 
tact. Nay, man can do better than the fish: he can 
express the eggs into a vessel where none of them will be 
Swept out of reach of the milt, or into the maws of the 
expectant throng of bystanding fishes; he can then press 
the milt into the same vessel, and, by stirring them to- 
gether, insure that the milt shall reach every egg. This 
is artificial fecundation. But let us examine the method 
employed. 
The operations of Pisciculturists, who have practised 
artificial impregnation, have been mostly confined to a 
few species of the family of Salmonide. The processes 
pursued will therefore apply only to a limited extent to 
the members of other families. 
Perhaps salmon and trout have received the most atten- 
tion. Both these species always seek clear, running, 
shallow water, and spawn in the autumn or early winter. 
A female and male, both ripe and ready to spawn, seek a 
proper place, and on a gravelly bed, swept clean of sand 
for a small space, the female deposits her eggs, and the 
male his milt. The operation is described with great 
minuteness by European writers, but I think that our 
brook trout (Salmo fontinalis) has not been observed suf- 
ficiently to ascertain whether its habits are precisely those 
of the European trout. ~ 
