286 CIRCULATORY APPARATUS. 



lias been passed from one sinus of Valsalva, over the point atwhicli 

 the '' line of contact " of the valve springs from the wall of the 

 vessel, into the next sinus, perform the same office as the musculi 

 papillares of the ventricle. The point of origin of the ' ' line of 

 contact " may now be moved further downwards without any 

 uncertainty as to the perfect competency of the valves. The 

 flap itself may become gradually flatter and more pointed, the 

 nodulus Arantii being kept in its old position, while the angle 

 formed by the two limbs of each ^Mine of contact" grows pro- 

 gressively less and less obtuse ; this also is well shown by the 

 specimen in the annexed figure. Briefly, the innocuous variety 

 of perforation or fenestration of the sigmoid valves is, in my 

 opinion, a connecting link between the sigmoid and the cuspid 

 types. 



D. Chronic Endocajxlitis, 



§ 253. In marked contrast to acute inflammation, and that 

 softening of the valvular tissues which results from it, chronic 

 endocarditis produces an extreme condensation and thickening 

 of the endocardium. Most persons suffering from chronic endo- 

 carditis give a histor}^ of former attacks of acute articular 

 rheumatism. Hencp we may admit the possibility, nay the 

 probability, that the endocardial changes may be of acute origin ; 

 a lesion, however insignificant, situated in the " line of contact " 

 of the valves, being continually exposed to mechanical irritation, 

 might refuse to heal; and might serve in consequence as a 

 starting-point and centre for a chronic inflammation, such as 

 we often meet with in neglected ulcers of the skin. 



On the other hand, it is necessary to throw the identity of 

 this process with chronic endoarteritis into strong relief In 

 either case, the microscope shows an inflammatory overgrowth 

 of connective tissue, followed by a secondary stage of calcifica- 

 tion, or, more rarely, of fatty degeneration of the newly-formed 

 products. The only special feature about chronic endocarditis 

 is the marked tendency of the inflamed parts to contract. 

 This tendency, of course, can only manifest itself in the dujDli- 

 catures of the membrane, since their one-sided attachment allows 

 a retraction of their free borders to take place. 



§ 254. Every point of the endocardial surface may be the 

 seat of chronic inflammation ; yet it affects the valves and the 



