A Mole ripped open by the ploughshare soils the path with its entrails, which soon turn purple; a Snake lies on the grass, crushed by the foot of a wayfarer who thought, the fool, that he was performing a good work; an unfledged bird, fallen from its nest, lies, a crushed and pathetic heap, at the foot of the tree that carried it; thousands of other similar remains, of every sort and kind, are scattered here and there, threatening danger through their effluvia, if no steps be taken to put things right. Have no fear: no sooner is a corpse signalled in any direction than the little undertakers come trotting along. They work away at it, empty it, consume it to the bone, or at least reduce it to the dryness of a mummy. In less than twenty-four hours, Mole, Snake, bird have disappeared and the requirements of health are satisfied. The same zeal for their task exists in the second class of scavengers. The village hardly knows those ammonia-scented refuges to which the townsman repairs to relieve his sordid needs. A little bit of a wall, a hedge, a bush is all that the peasant asks as a retreat at the moment when he would fain be alone. I need say no more to suggest the encounters to which such free and easy manners expose you! Enticed by the patches of lichen, the cushions of moss, the tufts of houseleek and other pretty things that adorn old stones, you go up to a sort of wall that supports a vineyard. Faugh! At the foot of the daintily-decked shelter, what an unconcealed abomination! You flee: lichens, mosses and houseleek tempt you no more. But come back on the morrow. The thing has disappeared, the place is clean: the Dung-beetles have been that way. To preserve the eyes from a frequent recurrence of offensive sights is, to these stalwart workers, the least of their tasks: a loftier mission is incumbent on them. Science tells us that the most dreadful scourges of mankind have their agents of dissemination in tiny organisms, the microbes, near neighbours of must and mould, on the extreme confines of the vegetable kingdom. At times of epidemic, the terrible germs multiply by countless myriads in the intestinal discharges. They contaminate those main necessities of life, the air and the water; they spread over our linen, our clothes, our food and thus diffuse contagion. We have to destroy by fire, to sterilize with corrosives or to bury underground such things as are infected with them. Prudence even demands that we should never allow ordure to linger on the surface of the ground. It may be harmless or it may be dangerous: when in doubt, the best thing is to put it out of sight. That is how ancient wisdom seems to have understood the thing, long before the microbe explained to us the need for vigilance. The nations of the east, more liable than we to epidemics, had formal laws in these matters. Moses, apparently echoing Egyptian knowledge in this case, tabulated the rules of conduct for his people wandering in the Arabian desert: