658 SPOKA.DIC DISEASES. 



synchronous with the cardiac movements. This sign is subject 

 to variety in tone and degree, depending upon the nature and 

 extent of the exudation or effusion. If much fluid be present, 

 the sound becomes lost, being replaced by a dull, churning noise ; 

 as the effusion diminishes by absorption, the to-and-fro friction 

 sound returns, unless, indeed, the pericardium has become 

 generally adherent to the heart's surface. If this sound be 

 associated with a deep-seated blowing or bellows murmur, 

 which sometimes begins to be distinguished when the other 

 ceases, or, in the words of Watson, appears to supervene upon 

 it or to take its place, the combination of sounds indicates an 

 affection of both the external and internal membranes — peri- 

 carditis and endocarditis. Dr. Stokes says, " that in respect of 

 morbid anatomy, cases of pericarditis may be arranged into three 

 classes. In the first class are to be placed those in v/hich there 

 is a slight though general effusion of coagulable lymph. In the 

 second, those in which there is superadded the secretion of 

 serum in abundance, causing distension of the pericardial sac. 

 In the third class are to be placed those cases in which signs 

 of muscular excitement, if not of myocarditis, are added to the 

 preceding conditions. 



"As the disease advances from the first to the last of these 

 forms, there is progressive increase in the violence of the in- 

 flammation, denoted in the second form by the occurrence of 

 excessive serous effusion, and in the last by the altered and 

 impaired condition of the heart itself. Death tends to occur by 

 syncope, induced by paralysis of the left ventricle. The 

 muscular substance of the heart is paralyzed, being of a dirty 

 brown or yellow colour, flabby, and easily torn — a condition 

 which speedily leads to passive dilatation of the heart, general 

 cachexia, and dropsy." 



Post mortem examinations, as conducted in the dissecting rooms, 

 go to prove that pericarditis, as evidenced by alterations of 

 structure, is not such a common form of disease as endocarditis. 

 In the human being it is stated that about thirty-three per cent, 

 of cases examined jpost mortem, varying from the ages of eighteen 

 to thirty-nine, and about seventy-one per cent, from ages between 

 forty-eight and eighty, show white spots in the heart. These 

 white spots are supposed by some pathologists to be due to 

 previous pericarditis, and by others to attrition from rubbing 



