ANEURISMS:—1. _External Characters_—size; shape; is the dilatation lateral or general in its relation to the vessel? Openings as seen externally; size, position, etc.; blood effused; quantity, etc. _After opening, notice_—contents; blood fluid or coagulated; fibrinous contents; laminations; their thickness; number; density; dryness; difference between outer and inner layers. Channel for blood: size; character of inner surface; how formed? Walls of aneurism: how formed; by all, or one coat of artery. Size of artery above and below aneurism.] The diseases of the aorta, and of arteries generally, which may claim attention in a post-mortem examination, are _inflammation_, _fatty degeneration_, _calcification_, _aneurism_, and _rupture_. =Inflammation.= This process may be found involving either the outer or inner coats of arteries. In the former case the walls appear thickened and infiltrated with a soft, jelly-like substance, which appears, at a more advanced stage in some cases, to degenerate into a purulent condition, while in others, great thickening of the coats, or even obliteration results. Inflammation of the inner coat generally precedes atheromatous or calcareous deposits, and is mostly confined to old persons. The roughened inner surface thus produced, may serve to collect fibrinous shreds from the blood, and thus be the occasion of the formation of emboli. Inflammation of arteries may result from injuries, from the presence of emboli, or may be spontaneous in its origin. While the more frequent seat of the disease is in the aorta, it may occur in any other artery. =Fatty Degeneration=, or atheromatous disease of arteries, is an important affection of those vessels, and is usually associated with aneurism. It is seen more frequently in the arch of the aorta, and consists in the presence of fine white streaks, situated in the substance of the lining membrane. The disease may be found in children as young as from three to seven years of age, but is more common with adults. As the disease advances, the middle coat becomes involved. The streaks gradually change into large, white, opaque patches. The middle coat becomes thinned, loses its elasticity, assumes a gray, semi-transparent appearance, and, at a later stage, becomes soft and cheesy, and sometimes even undergoes a form of liquification into a creamy fluid resembling pus, but dependent upon the abundant formation of fat globules, with scales of cholesterine and granular matter. While these destructive changes are going on in the inner and middle coats, and tending to their rupture, by a conservative process, the outer coat, upon which the strength of the vessel mainly depends, becomes thickened and strengthened by the accumulation of plastic matter.