During inflammation of arteries, the actions of the vessels are accelerated and attended with pain; the internal coat is found to be of a red colour, from increase of its vascularity, and not from its being merely tinged with the colouring part of the blood; or it is of a yellowish hue and rough, from the deposition of lymph on its surface, whilst the external coat is thickened by the infiltration of serum and lymph. When bloodvessels are inflamed from mechanical irritation, lymph is secreted on their internal coat, becomes organised, and obliterates their calibre; if deficient in nervous influence and circulating fluid at a particular point, there ulceration of their coats occurs; if violently injured or completely isolated, their coats mortify; and these circumstances must all be calculated on in the surgical treatment of arteries. A universal inflammatory state of the arterial coats is said to have existed, and its symptoms have been minutely detailed; but its occurrence seems to be extremely rare, and the treatment is medical. Inflammation is supposed to precede degeneration of the arterial coats. As a person advances in life the arteries lose elasticity, and the heart its balance with them; either the one or the other becomes dilated, their parietes are thickened, and the valves are altered in structure; the enlargement of the vessels is generally greatest towards their origin. The dilatation of arteries, more especially of the internal ones, is often very great; ultimately the internal coat gives way, and the external, with the surrounding tissues, yields in proportion as the blood diffuses itself. The internal tunic is occasionally burst in consequence of violent and sudden muscular exertion; and, even when the vessels are pretty limber and sound, effusion of lymph, and obliteration of the vessel ensue, or, more frequently, aneurism. Previously to the rupture of the internal tunic, however, there is, in most cases, a morbid alteration in the texture of the vessel. The internal coat becomes dry; its textures is more dense and less elastic, and consequently more brittle. Morbid matter is deposited between the middle and internal coats, and this, by stretching the latter still further, diminishes the elasticity and cohesion of their texture. The deposit is at first to a slight extent and of soft consistence, somewhat resembling condensed fatty matter. Afterwards it increases in quantity and consistence, becoming, instead of soft and yielding, dense, hard, and incompressible; in short, calcareous. [Illustration]