Again, as the insect world, averaging the whole, comes nearest to plants, (whose very essence is reproduction,) in the multitude of their germs; so does it resemble plants in the sufficiency of a single impregnation for the evolution of myriads of detached lives. Even so, the metamorphoses of insects, from the egg to the maggot and caterpillar, and from these, through the nympha and aurelia into the perfect insect, are but a more individuated and intenser form of a similar transformation of the plant from the seed-leaflets, or cotyledons, through the stalk, the leaves, and the calyx, into the perfect flower, the various colours of which seem made for the reflection of light, as the antecedent grade to the burnished scales, and scale-like eyes of the insect. Nevertheless, with all this seeming prodigality of organic power, the whole tendency is _ad extra_, and the life of insects, as electricity in the quadrate, acts chiefly on the superficies of their bodies, to which we may add the negative proof arising from the absence of sensibility. It is well known, that the two halves of a divided insect have continued to perform, or attempt, each their separate functions, the trunkless head feeding with its accustomed voracity, while the headless trunk has exhibited its appropriate excitability to the sexual influence.