Pus

A whitish, bland, cream-like fluid, heavier than water, found in phlegmonous absce es, or on the surface of sores. It is distinguished, according to its nature, into laudable or good pus, scrophulous, serous, and ichorous pus, . The most generally established opinion of the nature of pus, till within the last thirty years, has been, that it was composed both of solids and fluids; nor is the opinion even now entirely exploded, It was called true, or laudable pus, to distinguish it from a similar discharge, supposed to be composed wholly of fluids, called mucus. Yet the distinctions between pus and mucus have been very ill defined: there was thought to be a difference in their appearance to the eye; but the principal mark of distinction arose from a breach of surface being believed nece ary to the formation of pus, but not of mucus; consequently, when there was no breach in the solids, the discharge was considered to be only mucus. This notion of pus must have taken its rise from an idea that the solids of the parts were broken down into pus. The physiologists who formed this theory cannot, however, be said to have made their distinctions with great accuracy, since the discharge, in consequence of a blister being applied to the surface of the body, was admitted to be pus; although in such cases there is no lo of substance, and therefore the discharge should have been called mucus. To ascertain a real difference between the fluid formed where there is a breach in the solids, and that met with where the surface is entire, has been considered an object mieriting the attention of some of our most eminent surgeons, although the fluid formed under both these circumstances will be found to be, precisely the same. This inquiry must have arisen from their adhering to the hypothesis which has been mentioned, and which not being founded upon the principles of the animal economy, can never explain, satisfactorily, any of the operations in the living body. It will be found, upon investigation, that the appearance of a discharge produced from the secreting surface of an internal canal, or excretory duct, when the produce of the sup- purative inflammation, is exactly similar to a discharge, in consequence of inflammation in any other part of the body. ‘The only respect in which they differ is, that, in the one-case, there is no breach of surface, and in the other, there most commonly appears to be one. The one is suppuration alone, the other suppuration attended by ulceration. Mr. Home has been at considerable pains to collect those properties and circumstances which have heen ascertained respecting pus; and has endeavoured, by investigating others not so well understood, to render the history of it more complete. Through the whole of these observations, which are extracted from his work, pus will be considered as a fluid, whose formation depends upon a proce in the animal economy analogous to glandular secretions. Its production, Mr. Home ob~ serves, depends upon inflammation having previously taken place in some part of the body, etther in the common reticular membrane, upon the internal surface of circumscribed cavities, or the surfaces of internal canals, which form excretory ducts of: the body. Inflammation is nece ary for the formation of pus; and although a fluid, somewhat simi- Jar, is produced without any preceding inflammation, such fluids, not having all the properties of true pus, can be readily distinguished from it. 840