Trials by ordeal were very common in ancient times. The theory was that an innocent person was not injured by certain drugs, which, however, proved immediately fatal to the guilty.
Such trials at one time were customary in almost every part of the world. They were supposed to be perfectly just, so that no man could be held guilty of the death of those who succumbed. In practice, however, they were almost invariably corrupt. The Tanghinia venenifera of Madagascar was regularly used in ordeals, and is probably still employed by certain tribes. The seeds are exceedingly poisonous, but, if the authorities wish the accused person to escape, a strong emetic is mixed with the powdered seeds, and the poison has no time to act. This, however, is seldom the case, for in any savage nation no one who is popular and in good esteem with the king or other people in authority is at all likely to be accused. The fact of his being accused means in most cases that he is already condemned to die. Another ordeal plant is the Calabar Bean (Physostigma venenosa), found in West Africa. The plant is a climber belonging to the Leguminosæ, and the seeds, which are about an inch in diameter, are very deadly. The seed is conspicuously marked by the long, dark, sunken scar, where it was attached to the pod. Besides being exceedingly poisonous, it has also a curious effect upon the pupil of the eye, which is contracted by this drug.[108]
Another famous poison is produced from Datura stramonium and allied species. In tropical and sub-tropical countries, one is almost sure to find specimens of this handsome plant along almost every roadside. It is in fact one of the commonest tropical weeds. The leaves are large with fine spinose margins, and the flower is most conspicuous, as it is four or five inches long. This is supposed to be one of the drugs employed by the Obi wizards and witches. The most horrible rites, accompanied by atrocious cruelties, were performed amongst certain West African tribes and are continued amongst their descendants, the freed slaves of the West Indies and of the Southern United States.
Even to-day no white man is allowed to learn anything of the proceedings, but some form of devil-worship or Shamanism, accompanied by incantations and the use of poisonous drugs, still flourishes. Preparations of various sorts of Datura or Thorn-apple produce sometimes stupefaction, sometimes frantic, furious delirium, and sometimes death.
It is used in medicine as a narcotic and diuretic. Burton says that the Arabs smoke the leaves in pipes as a cure for influenza and asthma. It is sometimes used in Europe for neuralgia and even epilepsy. On the other hand, the priests of the ancient Peruvians used Datura to produce the ravings mistaken for inspiration, and it is supposed that the priests of Apollo at Delphi employed an allied species for the same purpose. In India, China, West Africa, and amongst the American blacks, it is still very commonly used.
A firm belief existed in the Middle Ages that every plant was a good remedy for something. There is a real basis in fact for this superstition, because every plant in the world has, so far as it can do so, to protect itself. The attacks of all sorts of grazing animals, from the mouse to the elephant, as well as the infinitely more dangerous and destructive insects, bacteria, and fungi, have to be provided for. By far the commonest form of protection is to develop within the plant strong medicinal or strongly smelling substances. These are far better as protective agents than the thorns and spines characteristic of deserts and half-deserts. We have already glanced at the turpentines and resins of Coniferous forests and at the odorous gums, frankincense, and myrrh of the Acacia scrub.
The use of poisons as protection is eminently characteristic of three of the natural orders. The Buttercups (Ranunculaceæ), the Potato order (Solanaceæ) and the Lilies. Of the first named, the celery-leaved, and indeed all Buttercups, are extremely poisonous; so also are all Aconites and Hellebores, as well as Marsh Marigold, Adonis, Clematis, and Larkspur.
Others, though not poisonous, are strongly medicinal, such as Blake Snakeroot, Hydrastis, etc. It is therefore inadvisable to use any of this order for food unless other people have eaten it without any inconvenience!
The beauty of the Lily order does not prevent it from being a particularly dangerous group of plants. Perhaps the worst poisons in this order are those of the Meadow Saffron (Colchicum autumnale), Herb Paris, Veratrum, Sabadilla, Lily of the Valley, Tulip, and Crown Imperial bulbs. Chamælirium, Trillium, Squills, Garlic, Solomon's Seal, Aloes, and the Sarsaparillas are all well-known medicines.
The order Solanaceæ is perhaps the most interesting, for it includes such dangerous poisons as Tobacco, Datura, Atropa belladonna (Deadly Nightshade), Henbane, Bittersweet (Solanum dulcamara), Common Nightshade (Solanum nigrum), and a very great many important drugs. Even the common potato contains a poisonous secretion solanin, and it is dangerous to eat green potatoes or the foliage. Yet the Tomato or Love Apple (so called because it was supposed to excite tender feelings) is both nutritious and delicious. Chillies and Cayenne Pepper (Capsicum spp.) are also commonly used as condiments.