260 Original Articles. [ April, 
Animal life, we find ourselves, at the commencement of our inquiry, 
on a higher platform (so to speak) than that from which we had to 
ascend in watching the constructive processes of the Plant. For, 
whilst the Plant had first to prepare the pabulum for its developmental 
operations, the Animal has this already provided for it, not only at the 
earliest phase of its development, but during the whole period of its 
existence ; and all its manifestations of Vital activity are dependent upon 
a constant and adequate supply of the same pabulum. The first of these 
manifestations is, as in the Plant, the building-up of the organism by 
the appropriation of material supplied from external sources under the 
directive agency of the germ. The ovum of the Animal, like the seed 
of the Plant, contains a store of appropriate nutriment previously 
elaborated by the parent; and this store suffices for the development 
of the embryo, up to the period at which it can obtain and digest ali- 
mentary materials for itself. That period occurs, in the different 
tribes of animals, at very dissimilar stages of the entire developmental 
process. In many of the lower classes, the embryo comes forth from 
the egg, and commences its independent existence, in a condition 
which, as compared with the adult form, would be as if a Human 
embryo were to be thrown upon the world to obtain its own subsist- 
ence only a few weeks after conception; and its whole subsequent 
growth and development takes place at the expense of the nutriment 
which it ingests for itself. We have examples of this in the class of 
Insects, many of which come forth from the egg in the state of ex- 
tremely simple and minute worms, having scarcely any power of move- 
ment, but an extraordinary voracity. The eggs having been deposited 
in situations fitted to afford an ample supply of appropriate nutriment 
(those of the Flesh-fly, for example, being laid in carcases, and those 
of the Cabbage-Butterfly upon a cabbage-leaf), each larva on its emer- 
sion is as well provided with alimentary material as if it had been 
furnished with a large supplemental yolk of its own; and by availing 
itself of this, it speedily grows to many hundred or even many thou- 
sand times its original size, without making any considerable advance 
in development. But having thus laid up in its tissues a large addi- 
tional store of material, it passes into a state which, so far as the ex- 
ternal manifestations of life are concerned, is one of torpor, but which 
is really one of great developmental activity : for it is during the pupa 
state that those new parts are evolved, which are characteristic of the 
perfect Insect, and of which scarcely a trace was discoverable in the 
larva; so that the assumption of this state may be likened in many 
respects to a re-entrance of the larva into the ovum. On its termina- 
tion, the Imago or perfect Insect comes forth complete in all its 
parts, and soon manifests the locomotive and sensorial powers by which 
it is specially distinguished, and of which the extraordinary predomi- 
nance seems to justify our regarding Insects as the types of purely 
Animal life. There are some Insects whose Imago-life has but a very 
short duration, the performance of the generative act being apparently 
the only object of this state of their existence: and such for the most 
part take no food whatever after their final emersion, their vital acti- 
vity being maintained, for the short period it endures, by the material 
