Long before the action of vegetable and mineral substances on human beings and animals was known, it is probable that poisonous bodies in some form were used by primitive man.
When injured in battle by perhaps a flint arrow-head, or stone axe, he sought for something to revenge himself on his enemy. In his search after curative remedies he also found noxious ones, which produced unpleasant effects when applied to the point of a weapon destined to enter the internal economy of an opponent.
He doubtless also became aware that the spear-points and arrow-heads on which the blood of former victims had dried, caused wounds that rapidly proved fatal, owing to the action of what we now call septic poisons. This probably led to experiments with the juices of plants, until something of a more deadly character was discovered.