222 Dr. Mac Culloch on the Changing 
The last of the important functions of fishes likely to be an impe- 
diment to this attempt, is their reproduction, or the act of spawn- 
ing; or rather, the circumstances necessary to ensure the vivifica- 
tion of the ova. The instincts, as they are called, or the peculiar 
habits of many fish in this important affair, seem often to be as ob- 
stinate as they are peculiar. This is notorious in the case of the 
salmon; which must not only deposit the ova in a river, but ina 
remote part of it, and even in the very stream in which it has itself 
been produced. Many fishes deposit their eggs only on shallow 
shores, although they inhabit the deep seas, Some frequent the es- 
tuaries of rivers for that purpose, others select mud, a third set sand, 
and others again the crevices of rocks, Yet as this part of the 
economy of fishes is a matter of necessity, it only remains to con- 
sider whether, being deprived of these conveniences to which they 
are instinctively addicted, they would not soon find it expedient to 
abandon them, and to adopt those alone which were within their 
reach. In this respect, the habits of the land animals with which 
we are acquainted, have been found susceptible of temporary, and 
even of permanent changes. Little acquainted as we are with the 
intellectual powers of fishes, or with the variety of character and 
capacity for education which may exist among them, it is bad rea= 
soning to presume that they are incapable of cultivation or change 
of habits, and that their sole talents are to catch, and their sole oc- 
cupation to eat, each other, 
Presurning, therefore that the ova must, as a matter of necessity, 
be deposited somewhere, it may be observed that inland lakes pre= 
sent all the varieties of bottom which are found in the sea, They 
receive rivers, have muddy bottoms, sandy and gravelly shores, and 
intricate rocky creeks; and, in some or other of these places, every 
fish may find a situation for its ova, more or less consonant to its 
natural habits. Nor is there any reason to suppose that where the 
perent lives, its ofispring could not be vivified ; since the vitality of 
the ova is far less likely to be affected by a change from salt water 
to fresh, than the complicated functions of the living and full grown 
animal, In a practical view, the power of continuing the species - 
under such a change, is proved by the facts already cited with ree 
