5. =Pericardium.= Note tension of sac, fluctuation, adhesions, thickness, character of inner surface, contents (amount, color, odor, presence of fibrin, blood or pus, gas). Normally there are about 5-10 c. c. of clear yellow fluid in the sac. Both peri- and epicardium normally are moist-shining, smooth, grayish and transparent. Large amounts of clear watery fluid may collect in the pericardial sac in slow death in cases of chronic valvular lesions, chronic nephritis, bronchitis and emphysema, but the surface of the peri- and epicardium remains smooth and shining. In inflammatory increase of the pericardial fluid the serous surfaces are dull, cloudy or dry, and may be covered with a layer of fibrin, the fluid is more or less cloudy and contains flakes or strings of fibrin, or may be purulent. The fibrinous exudate may be very extensive and from the movement of the heart be drawn out into bands, threads or villus-like prominences (cor hirsutum or villosum). Pericarditis is common in acute rheumatism, septicæmia, pyæmia, puerperal fever, osteomyelitis, pneumonia, and as a terminal infection in cardiac and renal disease. Tuberculosis is one of the most common causes of purulent, fibrinous and hemorrhagic pericarditis, particularly of the cor villosum. Examine surfaces for tubercles. The presence of blood in the pericardial exudate points usually to tuberculosis or malignant neoplasm, but in small amount may be found in various infections and intoxications. The age of the pericarditis may be judged by the amount of organization of the exudate, adhesions, thickenings, etc. “Milk spots,” “soldier’s spots,” “tendinous patches” or “friction scleroses” represent hyaline thickenings of the pericardium due to old pericarditis. Total synechia or atresia of the cavity may occur. As the result of calcification of an old pericarditic exudate the heart may be surrounded by a calcareous sheath (“stony heart,” “petrified heart”). Hæmopericardium results from the rupture of the heart, aorta, pulmonary artery or coronary vessel. Petechiæ of the peri- and epicardium are found in pyæmia, septicæmia, hæmophilia, scurvy, severe anæmia, leukæmia, chronic nephritis, and death from suffocation and various intoxications. Pneumopericardium may be due to perforating wounds, or to perforations from lungs, stomach or œsophagus, or to infections with gas-forming bacilli. Malformations are rare (diverticula, ectopia). Tuberculosis is usually secondary. Gummata are rare. Actinomycosis is usually secondary to actinomycosis of the neck or lungs. Primary neoplasms are rare. Secondary carcinoma and sarcoma (especially lymphosarcoma) are more frequent. Cysticercus, trichina and echinococcus are rare.