192 
SALMON. 
intervals of a year or two, and in some instances at an unusual 
season of the year. Fulness of habit or plumpness, or repletion, 
has certainly an important bearing on the spring and summer 
tendency to emigration, independent of the merely sexual 
impulse j and it is one effect of fresh water that the excess is 
soon abated, even when that water is of the purest kind; but 
when soiled with what flows from mines of copper and lead, 
it is so offensive not to say fatal, that these fish soon learn to 
seek safety in other haunts. Such is the case when the stream 
is polluted with what flows from some manufactories; and it 
was shewn by evidence before a Committee of Parliament, that 
where a river has become foul from tar or coal-gas, the flesh 
of a Salmon caught in it has become so infected— although the 
fish itself did not appear to be out of health — that even the 
smell from it was offensive at the table. 
An interesting portion of the history of the Salmon is con- 
nected with the attempts which have been made to propagate 
it by artificial means; which consist in obtaining the roe from 
beds in the river in which it had been shed spontaneously; or 
by pressing from the living fish the roe and milt, and placing 
them in pools of running water prepared for the purpose. They 
become developed, and the young are fed with prepared food, 
chiefly animal liver reduced to pulp, until they are ready to 
emigrate to the sea. It is by these means that several rivers 
which had been overfished and obstructed, and thus robbed of 
their native inhabitants, have recovered what they had lost; and 
in pursuit of what we must thus denominate an experiment, a 
considerable amount of knowledge has been thus acquired of 
the nature of the Salmon, where we w-ere before altogether 
ignorant The practice began in France by the ingenuity of 
two humble fishermen, named Gehin and Remy, of an obscure 
village called La Bresse in the Department of Vosges, and 
they first applied it to the propagation of Trout. The subject 
was presently taken up by the Government of that country; but 
it was made known among ourselves by one who wrote under 
the name of Piscarius; since which it has been adopted among 
us with success. Much effort has also been exerted to convey 
the Salmon to the British Colonies, in the southern hemisphere, 
and especially to Tasmania; whither the eggs have been con- 
veyed, enclosed in ice, and with so much success as is implied 
