Licence: Public Domain Mark
Credit: A text-book of pathology / by Alfred Stengel. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![Similar immunity may be characteristic of a given individual or of classes or species. Susceptibility to the action of poisons is further influenced by age and constitutional vigor. Children bear certain poisons better, comparatively speaking, than adults, while the reverse is true of other substances. Sometimes there are idio- syncrasies which lead to peculiar results not observed in the aver- age individual. In consequence of this, substances ordinarily not toxic may be extremely injurious to certain persons. Elimination.—The excretion of poisons may take place through the kidneys, lungs, the mucous membrane of the gastro- intestinal tract, or through the skin. In some instances a poison is almost completely eliminated in the excreta. In other cases it suffers complete change, and is not present at all in the excretions. The rate of elimination varies greatly, and is more or less depend- ent upon conditions of the system. Some poisons, as phosiDhorus and mercury, may be stored up within the body for a considerable period, subsequently suffering slow elimination. Classification.—The number of substances which may act as poisons is very great, and the manifestations are of very different sorts. Classification of poisons is therefore difficult and not en- tirely satisfactory. We may crudely distinguish between gaseous, liquid, and solid poisons; between animal and vegetable, organic and inorganic, and the like; but these classifications have no scientific value. From the point of view of the action of the poisons we may distinguish corrosive jpoisons, or those which have a local action ; organic or parenchyma-poisons, or those which act less strongly at the point of application than upon the vai'ious organs to which they are conveyed through the blood; blood-poisons, or those which exercise their effects primarily upon the blood; and the nerve-poisons, or those which disturb the functional activity of the nervous system without producing definitely discoverable lesions. Corrosive Poisons ; Escharotics ; Caustics.—Under this heading are included various acids, alkalies, and mineral poisons, such as sulphuric, nitric, oxalic, carbolic, and hydrofluoric acids, caustic potash or soda and ammonium, and gases like chlorin and bromin. Nitrate of sllvei', bichlorid of mercury, sulphate of copper, and other inorganic compounds have a similar action, and certain organic bodies, such as cantharidin and croton oil, belong to the same class. All these poisons exercise a destructive effect upon the cells with which they come in contact, partly by abstraction of water and partly as a result of a coagulating power or similar action. The degree of injury depends u])on the poison and the amount in contact with the tissues. There may be only a superficial injury of the outer layer of epithelial cells or extensive destruction. Reactive inflammation is almost always present. The affected](https://iiif.wellcomecollection.org/image/b21981668_0026.jp2/full/800%2C/0/default.jpg)
