A little pebble taken from the soil would affect our senses quite as strongly with its vague savour of fresh earth.

As a finder of underground fungi the Bolboceras is the rival of the dog.

It would be the superior of the dog if it could generalise; it is, however, a rigid specialist, recognising nothing but the _Hydnocystis_.

No other fungus, to my knowledge, either attracts it or induces it to dig.[6] Both dog and beetle are very near 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.