fondness for catnip is a case in point. The most primitive man,
then, must have inherited a racial or instinctive knowledge of
the medicinal effects of certain herbs; in particular he must
have had such elementary knowledge of toxicology as would enable
him to avoid eating certain poisonous berries. Perhaps, indeed,
we are placing the effect before the cause to some extent; for,
after all, the animal system possesses marvellous powers of
adaption, and there is perhaps hardly any poisonous vegetable
which man might not have learned to eat without deleterious
effect, provided the experiment were made gradually. To a certain
extent, then, the observed poisonous effects of numerous plants
upon the human system are to be explained by the fact that our
ancestors have avoided this particular vegetable. Certain fruits
and berries might have come to have been a part of man's diet,
had they grown in the regions he inhabited at an early day, which
now are poisonous to his system. This thought, however, carries
us too far afield. For practical purposes, it suffices that
certain roots, leaves, and fruits possess principles that are
poisonous to the human system, and that unless man had learned in
some way to avoid these, our race must have come to disaster. In
point of fact, he did learn to avoid them; and such evidence
implied, as has been said, an elementary knowledge of toxicology.

Coupled with this knowledge of things dangerous to the human
system, there must have grown up, at a very early day, a belief
in the remedial character of various vegetables as agents to
combat disease. Here, of course, was a rudimentary therapeutics,
a crude principle of an empirical art of medicine. As just
suggested, the lower order of animals have an instinctive
knowledge that enables them to seek out remedial herbs (though we