Let us repeat the experiment with the partly-consumed victuals. The result is the same. At one brief, nocturnal spell of work, the dainty is discovered underground and reached by means of a gallery which runs plumb to the spot where the morsel lies. There is no hesitation, no trial excavation guided by guesswork. This is proved by the surface of the soil, which everywhere is just as I left it when I smoothed it down. The insect could not have made straighter for the coveted object had it been guided by sight; it always digs at the foot of the straws, my sign-posts. The Dog, nosing the ground for truffles, hardly achieves this degree of precision. Has the hydnocystis then a very pungent smell, able to give such positive information to its consumer’s scent? Not at all. To our nostrils it is a neutral object, devoid of any appreciable olfactory character. A tiny pebble taken out of the ground would impress us just as much with its faint aroma of fresh earth. As a revealer of underground fungous products, the Bolboceras here rivals the Dog. He would even rise superior to the Dog, were he able to generalize. But he is a rigorous specialist: he knows only the hydnocystis. Nothing else, so far as I am aware, tempts him to dig. [41] Both of them search the subsoil very closely, at the level of the ground; and the object which they seek is not far down. Were they farther away, neither the Dog nor the insect would notice effluvia so subtle, not even the smell of a truffle. To make an impression at a great distance, powerful odours are needed, capable of perception by our olfactory sense. Then the exploiters of the odorous thing come hastening up on all sides from afar. When, for the purpose of my studies, I require insects that dissect corpses, I expose a dead Mole in the sun, in a distant corner of the enclosure. As soon as the animal swells, distended by the gases of putrefaction, and the skin begins to turn green and the fur to fall from it, up come numbers of Silphæ [42] and Dermestes, [43] Necrophori [44] and other Burying-beetles, of whom one would find not a single specimen in the garden, or even in the neighbourhood, without this bait. They have been informed by their sense of smell, at a great distance all around, whereas I myself can avoid the stench by taking a few steps back. Compared with their scent, mine is contemptible; but still, in their case as well as mine, there is really here what our language calls a smell.