ar the subsoil which they scrutinise; the
object they seek is at no great depth. At a greater depth neither dog
nor insect could perceive such subtle effluvia, nor even the odour of
the truffle. To attract insect or animal at a great distance powerful
odours are necessary, such as our grosser senses can perceive. Then the
exploiters of the odorous substance hasten from afar off and from all
directions.

If for purposes of study I require specimens of such insects as dissect
dead bodies I expose a dead mole to the sunlight in a distant corner of
my orchard. As soon as the creature is swollen with the gases of
putrefaction, and the fur commences to fall from the greenish skin, a
host of insects arrive--Silphidae, Dermestes, Horn-beetles, and
Necrophori--of which not a single specimen could ever be obtained in my
garden or even in the neighbourhood without the use of such a bait.

They have been warned by the sense of smell, although far away in all
directions, while I myself can escape from the stench by recoiling a few
paces. In comparison with their sense of smell mine is miserable; but in
this case, both for me and for them, there is really what our language
calls an odour.

I can do still better with the flower of the Serpent Arum (_Arum
dracunculus_), so noteworthy both for its form and its incomparable
stench. Imagine a wide lanceolated blade of a vinous purple, some twenty
inches in length, which is twisted at the base into an ovoid purse about
the size of a hen's egg. Through the opening of this capsule rises the
central column, a long club of a livid green, surrounded at the base by
two rings, one of ovaries and the other of stamens. Such, briefly, is
the flower or rather the inflorescence of the Serpent Arum.

For two days it exhales a horrible stench of putrid flesh; a dead dog
could not produce such a terrible odour. Set free by the sun and the
wind, it is odious, intolerable. Let us brave the infected atmosphere
and approach; we shall witness a curious spectacle.

Warned by the stench, which travels far and wide, a host of insects are
flying hither; such insects as dissect the corpses of frogs, adders,
lizards, hedgehogs, moles and field-mice--creatures that the peasant
finds beneath his spade and throws disembowelled on the path. They fall
upon the great leaf, whose livid purple gives it the appearance of a
strip of putrid flesh; they dance with impatience, intoxicated by the
corpse-like odour which to