EXTERNAL DISEASES, AND THEIR CURE. In this lecture I shall treat of external disorders, which may take their origin either from injuries, or from internal acrimony of habit; for whatever disturbs the animal œconomy, prevents the natural order of the fibres, and those again when in disorder, corrupt the fluids. Be the causes what they will, certain it is, that there is a strict connexion between the external and the internal parts, to which due regard ought ever to be paid. I shall without delay proceed to their various kinds. ------------------------------------------- SECT. I. _Of Inflammation_ When either the solids are so injured that they will not transmit the circulation with their natural freedom; or when the humours are become so acrimonious, as to constrict the small tubes, that part of the fluids becomes confined in them, there must then of course be an obstruction of the circulation of the fluids, thence accumulation must follow and consequently swell the parts. And this is the nature of an inflammation. The blood being obstructed, the parts must naturally swell; the blood being forced into the small lymphatic vessels, thence proceed the redness; and lastly, from the vessels being distended and irritated by the stagnated humours, proceeds the pain. An inflammation terminates three different ways. When the solids relax, or the fluids become attenuated, so that the accumulated humours disperse, and are admitted a free circulation again, it is termed _resolution_; and this is the best and most favourable way for an inflamed and tumified part to terminate. When some of the small vessels by the over-stretching of their contained humours break, together with the lymphatic vessels, and the extravasated blood intermixed with lymph is converted into matter, it is termed a _suppuration_; this is also a favourable way of termination, provided the matter is properly concocted and discharged, and the parts properly healed up again. And this ought to be the second indication when the first does not succeed. When however the imprisoned humours enclosed by their tubulæ are inspissated, and mix irregularly with the solids that contain them, obstinate tumours are apt to ensue. This is the third kind of termination, and should be avoided if possible; for it either becomes tedious, or occasions malignant ulcers; which in glandulous parts are the first foundation of cancers.