Another kind of poison was met with on Lake Nyassa, which was said to be used exclusively for killing men. It was put on small wooden arrow-heads, and carefully protected by a piece of maize-leaf tied round it. It caused numbness of the tongue when the smallest particle was tasted. The Bushmen of the northern part of the Kalahari were seen applying the entrails of a small caterpillar which they termed 'Nga to their arrows. This venom was declared to be so powerful in producing delirium, that a man in dying returned in imagination to a state of infancy, and would call for his mother's breast. Lions when shot with it are said to perish in agonies. The poisonous ingredient in this case may be derived from the plant on which the caterpillar feeds. It is difficult to conceive by what sort of experiments the properties of these poisons, known for generations, were proved. 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.