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.[107] [107] The pupil of the eye is _enlarged_ by belladonna. 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.