PERICARDITIS. 397 



described as occurring in pleurisy. The exudation soon separates into 

 a liquid and a solid portion. The former may be very scanty in quantity, 

 or may amount to several pounds. Small accumulations of it form in 

 the upper and anterior part of the sac, at the root of the great vessels, 

 while the heart gravitates to the lower portion. When in larger 

 amount, the entire sac is distended, the lungs compressed, particularly 

 the lower lobes of the left lung ; even dilatation of the thorax, in the 

 region of the heart, may be the conaequence. 



Although the exudation always contains some young cells or pus- 

 corpuscles, their quantity is often extremely small, and the liquid is 

 then tolerably clear, and either colorless or of a yellowish tinge. If 

 more or less of coagulated fibrin be found in the liquid, it is called 

 sero-fibrinous. A smaller quantity of fibrin imparts a slightly-flaky 

 opacity to the liquid part of the exudation, or may produce a slimy 

 turbid deposit upon the pericardium. Sometimes delicate fibres, like 

 cobwebs, pass across from one surface to another. This we find, chiefly, 

 in cases in which inflammation has been transmitted from some neigh- 

 boring organ to the pericardium. 



In other cases, the exudation is very heavily charged with fibrin, 

 which is extensively precipitated upon the walls of the pericardium, 

 forming reticulated and villous masses. The surface of the heart ac- 

 quires the aspect of a cut sponge, or of one of two surfaces smeared 

 with butter, which have been quickly pulled asunder after having been 

 brought into contact. A heart upon which this sort of villous, ragged 

 precipitate has formed, is called cor villosum or hirsutum. This is the 

 kind of exudation most commonly met with in the pericarditis of acute 

 articular rheumatism. 



In many cases an escape of blood from the ruptured capillaries 

 accompanies the exudation, thus producing a hcemorrhagic exudation. 

 If there be but little blood mixed with it, the serum has a reddish color ; 

 if the flow of blood be considerable, the effused mass may resemble a 

 pure extravasation, and assume a blackish hue. Even the fibrinous 

 deposit, otherwise whitish yellow in color, is stained, either dark or 

 bright-red, by admixture of the blood. Haemorrhagic exudation some- 

 times occurs in recent pericarditis, which has attacked cachectic sub- 

 jects, topers, tuberculous persons, or those suffering from advanced 

 Bright^ disease. It is still more frequently observed when the in- 

 flammation, instead of invading the true pericardium, has attacked the 

 young connective tissue which has developed upon it, and in which 

 very large but delicate and thin-walled vessels form, which are very 

 liable to rupture. In these cases we often find miliary tubercles de- 

 veloped in the young adventitious membrane, besides the haemorrhagic 

 exudation ; and this is what we commonly find in the form known as 



