The alcohol group is a term which may well be applied to another group of poisons consisting of alcohol itself, and all those substances which contain the different alcohols or their allies, such as ether, chloroform, chloral, chloral hydrate, sulphonal, trional, tetronal, amylene hydrate, paraldehyde, etc. To this group belong many important sleep-producing remedies. Poisoning may be induced by all of them, depending on the amount taken, and the grade of concentration. The symptoms are so well known, as in the case of alcohol-poisoning, that further reference need not he made at this place, but the reader is referred to the chapter on Atconotism.
The alcohols and their allies constitute a most important group of nerve poisons, especially in Occidental lands ; hut another group serves a similar purpose for the Orient—namely, the group of which opium is the most important and almost the only member. Opium contains morphine and methyl-morphine, or codeine, with some fourteen or fifteen other alkaloids. A number of other synthetic modifications of morphine are known under the names heroine, peroine, dionine, etc. These have a very characteristic action on the nervous structures.
The symptoms of poisoning by opium vary considerably in different individuals, but, if sufficiently large doses are taken, the first sign is usually that of a slight exaltation, which may be manifested by some increase in the alertness of the individual ; the attention seems to be a little more intense, although narrowed in scope, and for a time the perceptions of light, sound, touch, taste, etc., are slightly increased in acuteness. Some individuals suffer from nausea and vomiting at this time ; and by the loss of the sub stance from the body the patient passes from under its influence. In others, however, there is a gradual benumbing of the senses ; the patients have a very distinct feeling of well-being, the blood-vessels dilate, the extremities become warm and comfortable, and a moderate feeling of beatitude spreads over the entire body. All outside impressions, particularly those of a painful nature, are cut off, and the patient lives in a world of his own making, usually immersed in rapt or languorous thoughts of comfort. The stage of deepened lethargy follows, and the patient may sleep in a fitful manner, and on awaking have a very uncomfortable headache, a sense of nausea and vomiting, inability to pass urine, and itching and discomfort of the skin.
If, however, the dose has been larger, the symptoms of insensibility deepen ; the breath becomes slow and snoring ; the pupils, which have been slightly contracted heretofore, become much more markedly so ; perspira tion is absent; the skin becomes cold and clammy, although at first warm, and little by little the patient passes into deeper and deeper coma with slower and respiration, till paralysis of breathing causes death.
The amount necessary for this result varies with individuals, but half a grain of morphine or a grain of opium has caused death in some cases. As for the symptoms which are due to chronic opium-poisoning, or the use of opium, all these have already been discussed under the head of OPIUM POISONING. Indian hemp may also be classified with this group, although it has some variations of its own. See CANNABIS INDICA.
Poisons which act on the spinal cord comprise still another group. One set is capable of exciting the chief cells in this structure, while another set depresses the muscle terminals of the spinal nerves, so that they constitute contrasting groups. To the motor excitants, as they are termed, belong characteristically strychnine, the poison of tetanus, narcotise and thebain (two of the alkaloids of opium), and brucin, found also in one of the species of Strychnos ; whereas the principal members of the motor depressant group are conium (poison-hemlock), and curare, an Indian arrow-poison of South America. The symptoms of poisoning by strychnine and the members of the group come on very rapidly. As these are discussed in detail under the head of STRYCHNINE-POISONING, a reference to that article will suffice. For the symptoms of poisoning by a motor depressant, see HEMLOCK-POISONING.
The metallic poisons form another important and large group. Here the chief action consists of an interchange between the metal and the cells of the body in general. The blood and the tissue-cells of the various organs are involved, and great variation is to be found in the action of the different metals. Thus, some metals will have greater affinity for the tissues of the kidney and liver (as, for example, arsenic and phosphorus), while others primarily affect the tissues of the nervous system. For this reason general principles cannot be easily drawn with reference to their toxicology, further than that they affect the entire metabolism of the body. As a rule, this action is useful if small amounts of the drug are given, but the stage of irritation and stimulation rapidly passes into one of over-stimulation and destruction. Hence the apparent disparity of action of these drugs when given in small doses and when given in larger ones. There is really no difference in the kind of action. It is solely one of degree.