A remarkable and interesting feature of this case was, the little inconvenience experienced by the patient from so grave a malady, and one usually attended with great suffering. =Rupture.= Spontaneous rupture of the aorta is a very rare occurrence, and probably never happens except the coats have first been weakened by disease. Hence, in all of these cases, there will be found atheromatous softening, and generally thinning of the walls by dilatation. In this condition, some violent muscular effort may result in rupture at the most weakened point, and this will be generally at that portion of the aorta within the pericardium, the external coat being weaker here than at any other point. Where the dilatation of the diseased and weakened vessel has resulted in the formation of an aneurism, rupture of this will be the more frequent termination. This may take place into the œsophagus, as in the case reported, or into the trachea, the pericardium, either pleural cavity, or upon the surface of the body. Rupture of the coronary arteries, of the arteries of the brain, various branches of the abdominal aorta, and arteries of the extremities, have occasionally been found, when softened by fatty degeneration or atheromatous disease. Section VII. THE PLEURA. [=Notice=: _Condition of membrane_—inflamed; extent and position of; thickened; transparent or opaque; rough or smooth. _Contents_—blood, gas, serum, pus, amount and probable source of. _Adhesions_—general or local; firmness of, etc.] Like other serous membranes, the pleura is liable to _inflammation_, both acute and chronic, with their results—_plastic_, _serous_, or _purulent effusions_, _adhesions_, etc. =Inflammation.= The first change which is observed in inflammation of the pleura (pleurisy) is a loss of the shining, transparent appearance of that membrane, it becoming dull and opaque. Red injected vessels, in minute ramifications, sometimes radiating from single points, in others more uniformly diffused, will be noticed. Often the surface will present a red mottled appearance, with here and there small points of extravasation. This condition having existed for from six to twenty-four hours, certain results follow—at least in the acute form—which give rise to what is known as =Plastic Effusion.= Soon after the inflammatory process is fully established, there will appear upon the surface a small quantity of clear fluid, which, as it increases in quantity, undergoes coagulation, and thus gradually covers the surface with a jelly-like layer of variable thickness and honey-comb surface. A thin fluid of a straw color, will be found oozing from the surface, which is increased as the coagulated membrane is cut or torn. This condition may be extended over the whole surface of both the costal and pulmonary pleura, or may be confined to a limited portion.