And consider mimicry. According to the theory of evolution, certain insects would utilize their resemblance to certain others in order to conceal themselves, and to introduce themselves into the dwellings of the latter as parasites living at their expense. Such would be the case with the Volucella, a large fly whose costume, striped with brown and yellow bands, gives it a rude resemblance to the wasp. Obliged, if not for its own sake at least for that of its family, to force itself into the wasp's dwelling as a parasite, it deceitfully dresses itself, we are told, in the livery of its victim, thus affording the most curious and striking example of mimicry; and naturalists insufficiently informed would regard it as one of the greatest triumphs of evolution. Now what does the Volucella do? It is true that it lays its eggs without being disturbed in the nest of the wasp. But, as the rigorous observer will tell you, it is a precious auxiliary and not an enemy of the community. Its grubs, far from disguising or concealing themselves, "come and go openly upon the combs, although every stranger is immediately massacred and thrown out." Moreover, "they watch the hygiene of the city by clearing the nest of its dead and ridding the larvae of the wasps of their excretory products." Plunging successively into each chamber of the dormitory the forepart of their bodies, "they provoke the emission of that fluid excrement of which the larvae, owing to their cloistration, contain an extreme reserve." In a word, the grubs of the Volucella "are the nurses of the larvae," performing the most intimate duties." (9/1.) What an astonishing conclusion! What a disconcerting and unexpected reply to the "theories in vogue"! Fabre, however, with his poetic temperament and ardent imagination, seemed admirably prepared to grasp all that vast network of relations by which all creatures are connected; but what proves the solidity of his imperishable work is that all theories, all doctrines, and all systems may resort to it in turn and profit by his proofs and arguments. And he himself, although he boasts with so much reason of putting forward no pretensions, no theories, no systems, has he not even so yielded somewhat to the suggestions of the prevailing school of thought, and have not his verdicts against evolution often been the more excessive in that he has paid so notable a tribute to the evolutionary progress of creation? In the first place, he is far from excluding the undeniable influence of environing causes; the immense role of those myriad external circumstances on which Lamarck so strongly insisted; but the work of these factors is, in his eyes, only accessory and wholly secondary in the economy of nature; and in any case it is far from explaining the definite direction and the transcendent harmony which characterize evolution, both in its totality and in its most infinitesimal details.