A profound and comprehensive renewal is effected in the vital statics of the metamorphosed insect; the substance, which is actually still the same, enters into fusion, subtilizes its atomic structure and becomes liable to sensory vibrations which are the first appanage of the nubile specimen. The armour of the wing-cases, the blades, tufts and quivering stems of the antennæ, the legs fit for running and wings fit for flying: all these are magnificent and yet all these are nothing. Something else towers high above them. The transformed insect has acquired a new life, more active and richer in sensations. A second birth has taken place in which all is renewed, in the invisible and intangible even more than in the material domain. It is more than a molecular rearrangement; it is the development of aptitudes unknown in the past. The larva, generally a mere scrap of intestine, lived a placid and very monotonous existence and lo, in view of the future instincts, metamorphosis revolutionizes its substance, distils its humours and refines the centres of energy atom by atom. An enormous leap is made towards progress, but the new state has not the sturdy equilibrium of the first, perfection has been gained at the cost of stability; and so the insect dies of an ordeal which the grub would support with impunity. With the Acridians and the Orthoptera in general, conditions are quite different. Here there is no real metamorphosis, utterly changing the structure, the mode of life and the habits. The insect remains, all its life long, very much what it was on leaving the egg. It is born in a shape which the future will hardly modify, with habits which will not be altered by time. It undergoes no renovation, no sudden growth. In its infancy already it possesses the temperament of the adult; and as such it is deprived of the immunity enjoyed by rudimentary organisms. Exempted from a probationary period in the grub state, the short-coated Locust suffers from the drawbacks of a too rapid development. He perishes as quickly as the adult, whom he resembles in all but a few details. I will not deny that the explanation which I have given may not be the right one; and I will not insist upon it. A cast of the net into the depths of the unknown does not always bring up to the surface the correct idea, a very rare catch. A far-reaching fact is acquired nevertheless, even though it remain unexplained. Metamorphosis modifies the organic substance to the degree of changing its innermost properties. The Scorpion’s poison, a reagent of transcendental chemistry, distinguishes the flesh of the larva from that of the adult; it is kindly to the first and deadly to the second.