Faint as are the effluvia of this subterranean fungus, the prospecting epicure, being specially equipped, perceives them with the greatest ease; but then he operates at close range, from the surface of the soil.

The truffle-dog is in the same case; he searches with his nose to the ground.

The true truffle, however, the essential object of his search, possesses a fairly vivid odour.
But what are we to say of the Great Peacock moth and the Oak Eggar, both of which find their captive female?
They come from the confines of the horizon.

What do they perceive at that distance?
Is it really an odour such as we perceive and understand?
I cannot bring myself to believe it.
The dog finds the truffle by smelling the earth quite close to the tuber; but he finds his master at great distances by following his footsteps, which he recognises by their scent.

Yet can he find the truffle at a hundred yards?
or his master, in the complete absence of a trail?
No.