Probably the animal instincts, which have become so obtuse by civilization, that children in England eat the berries of the deadly nightshade (_Atropa belladonna_) without suspicion, were in the early uncivilized state much more keen.

In some points instinct is still retained among savages.

It is related that in the celebrated voyage of the French navigator, Bougainville, a young lady, who had assumed the male attire, performed all the hard duties incident to the calling of a common sailor; and, even as servant to the geologist, carried a bag of stones and specimens over hills and dales without a complaint, and without having her sex suspected by her associates; but on landing among the savages of one of the South Sea Islands, she was instantly recognized as a female.

They began to show their impressions in a way that compelled her to confess her sex, and throw herself on the protection of the commander, which of course was granted.

In like manner, the earlier portions of the human family may have had their instincts as to plants more highly developed than any of their descendants--if indeed much more knowledge than we usually suppose be not the effect of direct revelation from above.
The Mukuru-Madse has a deep rocky bed.