The little that the breach allows us to see—for it is pretty quickly repaired—tells us what goes on under ordinary conditions. Without the aid of sight, we see the grub evacuating at intervals and renewing its store of cement; we can follow it as it gathers the clod with the tips of its mandibles, squeezing it with its legs, dividing it to its liking and spreading it with its mouth and forehead on the weak spots of the wall. A rolling motion of the rump gives it a polish. Without borrowing any extraneous materials, the builder finds within itself the building-stones of its edifice. A similar stercoral talent is the portion of other big-bellied larvæ, which wear around their abdomen a wide brown sash, the insignia of their craft. With the contents of their intestinal wallet they build the hut in which metamorphosis takes place. All tells us of the high economy which knows the secret of turning the abject into the decent and of producing from a box of ordure the Golden Cetonia, the guest of the roses and the glory of the spring. CHAPTER II SAPRINI, DERMESTES AND OTHERS Twenty thousand, Réaumur [13] tells us, twenty thousand embryos in the body of the Grey Flesh-fly! [14] Twenty thousand! What does she want with this formidable family? With offspring that reproduce themselves several times in a year, does she intend to dominate the world? She would be capable of it. Speaking of the Bluebottle, [15] who is far less prolific, Linnæus [16] already wrote: “Three Flies consume the carcase of a Horse as quickly as a Lion could do it.” What could not the other accomplish? Réaumur reassures us: “Despite such amazing fertility,” he says, “these sorts of Flies are not commoner than others which resemble them and in whose ovaries we find only two eggs. The maggots of the former are seemingly destined to feed other insects, which very few of them escape.” Now which are the insects charged with this task of extirpation? The master suspects their existence; he guesses that they are there, without having had the occasion to observe them. My retting-vats provide me with the means of filling up this historical gap; they show me the consumers at their appointed task of thinning out the obtrusive maggot. Let me record this tragic business.