Page:Treatise on poisons in relation to medical jurisprudence, physiology, and the practice of physic (IA treatiseonpoison00chriuoft).pdf/689

 poisons that act in a very peculiar manner. They induce violent spasms, exactly like tetanus, and cause death during a fit, probably by suspending the respiration. But they do not impair the sensibility. During the intervals of the fits the sensibility is on the contrary heightened, and the faculties are acute.

Death, however, does not always take place by tetanus. In some cases the departure of the convulsions has been followed by a fatal state of general and indescribable exhaustion.

Besides thus acting violently on the nervous system, they also possess local irritant properties; but these are seldom observed on account of the deadliness and quickness of their remote operation on the spine and nerves.

They exert their action by entering the blood-vessels. The dose required to prove fatal is exceedingly small. The organ acted on is chiefly the spinal cord; but sometimes they seem also to act on the heart.

They seldom leave any morbid appearances in the dead body. Like the other causes of death by obstructed respiration, such as drowning and strangling, they produce venous congestion; but this is frequently inconsiderable. Sometimes, however, they leave signs of inflammation in the alimentary canal.

Their energy resides in peculiar alkaloids. The only poisons included in this group, are derived from the genus Strychnos. The bark of Brucea antidysenterica was long supposed also to possess similar properties; but it is now known that the bark of Strychnos nux-vomica was mistaken for the bark of that tree. Several species of Strychnos have been examined, namely, the S. Nux-vomica, the S. Sancti Ignatii or St. Ignatius bean, the S. colubrina, or snake-wood, the S. tieuté, which yields an Indian poison the Upas tieuté, the S. Guianensis, and likewise the S. potatorum and Pseudo-kina; and all have been found to possess the same remarkable properties, except the last two, which are inert. All of them, except the S. pseudo-kina, and probably the S. potatorum, contain an alkaloid to which their poisonous properties are owing. This is strychnia or strychnin, a substance which has lately been made the subject of many experiments by chemists and physiologists. Of Poisoning with Strychnia.

Strychnia was discovered by Pelletier and Caventou soon after the discovery of morphia. For an account of the best process for preparing it, the reader may consult a paper by M. Henry in the journal quoted below.

Its leading properties are the following. Its crystals when pure are elongated octaedres. It has a most intensely bitter taste, perceptible, it is said, when a grain is dissolved in 80 pounds of water.