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121 Beneath the left lung the heart is situated and partially inclosed in another membranous bag termed the pericardium, which closely invests, supports, and protects it. The heart has two sides, the one devoted to the circulation of the blood through the lungs, and the other to its circulation through the frame generally. Each side is divided into two compartments, the one above, the other below, which are termed the auricles and ventricles. The right auricle as well as the ventricle is larger than the left, and its parietes are thinner. The longitudinal tendinous cords of the ventricle are more firm and distinct in the pig than in the ox or sheep, and the fleshy prominences shorter. The tendinous cords of the left ventricle are few in number, large, and ill defined. The aorta of the pig separates almost immediately after its commencement into two trunks, the smaller of which leads forwards and gives forth those arteries which in other animals arise from the cross of this artery; and the other, which is longer in diameter, inclines backwards: these are usually termed the anterior and posterior aorta.

The beating of the heart may be felt on the left side, whence also the pulse may be taken, or from the femoral artery which crosses the inside of the thigh in an oblique direction. In swine in a state of health the pulsations are from seventy to eighty in a minute.

This appears to be a more common malady than is generally suspected, for in repeated cases of sudden death, where a post-mortem examination has been made, there have been found fleshy excrescences or tumors on the tricuspid valves. We believe Mr. Cartwright, whose name we have already mentioned, was one of the first persons who drew attention to this disease. The only marked precursory symptoms appear to be inappetency and very shortly before death difficulty of breathing and evident distress. In one pig that died thus suddenly, Mr. Cartwright found several uneven watery excrescences, some as large as marbles, growing from the edge of the auricula-ventricular valves of the left side; also several small papillary growths, all of which served three parts to close up the ventricular opening.

In another case he found a loose, jagged, watery excrescence growing from the whole surface of the tricuspid valves, closing up, in a great measure, the ventricular opening, and projecting at least half an inch into the left auricle. In a third, the valves of the left auricle were thickened, schirrous, and presented a ragged uneven surface. The orifice of the ventricle was almost closed up by this diseased substance, and a portion had forced its way into the aorta. This disease was always found in the left side of the heart, and in