ADYNAMIA. 367 



as the predisponent cause of syncope, deserves to be inquired 

 into. 



It is, in the first place, obvious that the operation of some of 

 those causes depends entirely upon an idiosyncrasy in the per- 

 sons upon whom they operate ; which, however, I cannot pre- 

 tend to explain. But, in the next place, with respect to the 

 greater part of the other causes, their effects seem to depend 

 upon a temperament which is in one degree or other in common 

 to many persons. This temperament seems to consist in a 

 great degree of sensibility and mobility, arising from a state of 

 debility, sometimes depending upon original conformation, and 

 sometimes produced by accidental occurrences in the course of 

 life. 



MCLXXXV. The second set of the remote causes of 

 syncope (MCLXXIV.), or those acting directly upon the 

 heart itself, are certain organic affections of the heart itself, or 

 of the parts immediately connected with it, particularly the 

 great vessels which pour blood into, or immediately receive it 

 from the cavities of the heart. Thus, a dilatation or aneurysm 

 of the heart, a polypus in its cavities, abscesses or ulcerations 

 in its substance, a close adherence of the pericardium to the 

 surface of the heart, aneurysms of the great vessels near to the 

 heart, polypus in these, and ossifications in these or in the 

 valves of the heart, are one or other of them conditions which, 

 upon dissection, have been discovered in those persons who had 

 before laboured under frequent syncope. 



MCLXXXVI. It is obvious, that these conditions are all 

 of them, either such as may, upon occasion, disturb the free 

 and regular influx into, or the free egress of the blood from, 

 the cavities of the heart ; or such as may otherwise disturb its 

 regular action, by sometimes interrupting it, or sometimes ex- 

 citing it to more violent and convulsive action. The latter is 

 what is named the Palpitation of the Heart, and it commonly 

 occurs in the same persons who are liable to syncope. 



MCLXXXVI I. It is this, as I judge, that leads us to per- 

 ceive in what manner these organic affections of the heart and 

 great vessels may occasion syncope : For it may be supposed, 

 that the violent exertions made in palpitations may either give 

 occasion to an alternate great relaxation (MCLXXVIIL), or 



