on of
those vital forms (the _nisus formativi_) the adequate and the sole
measure of which is to be sought for in their several organic products.
But as if a weakness of exhaustion had attended this advance in the same
moment it was made, Nature seems necessitated to fall back, and re-exert
herself on the lower ground which she had before occupied, that of the
vital magnetism, or the power of reproduction. The intensity of this
latter power in the fishes, is shown both in their voracity and in the
number of their eggs, which we are obliged to calculate by _weight_, not
by _tale_. There is an equal intensity both of the _immanent_ and the
_projective_ reproduction, in which, if we take in the comparative number
of individuals in each species, and likewise the different intervals
between the acts, the fish (it is probable) would be found to stand in a
similar relation to the insect, as the insect, in the latter point, stands
to the system of vegetation. Meantime, the fish sinks a step below the
insect, in the mode and circumstances of impregnation. To this we will
venture to add, the predominance of _length_, as the _form_ of growth in
so large a proportion of the known orders of fishes, and not less of their
rectilineal path of motion. In all other respects, the correspondence
combined with the progress in individuation, is striking in the whole
detail. Thus the eye, in addition to its moveability, has besides acquired
a saline moisture in its higher development, as accordant with the life of
its element. Add to these the glittering covering in both, the splendour
of the scales in the one answering to the brilliant plates in the
other,--the luminous reservoirs of the fire-flies,--the phosphorescence and
electricity of many fishes,--the same analogs of moral qualities, in their
rapacity, boldness, modes of seizing their prey by surprise,--their gills,
as presenting the intermediate state between the spiracula of the grade
next below, and the lungs of the step next above, both extremes of which
seem combined in the structure of birds and of their quill-feathers; but
above all, the convexity of the crystalline lens, so much greater than in
birds, quadrupeds, and man, and seeming to collect, in one powerful organ,
the hundred-fold microscopic facettes of the insect's _light_ organs; and
it will not be easy to resist the conviction, that the same power is at
work in both, and reappears under higher auspices. The intention of Nat