II -MOEBID ANATOMY OF THE CIRCULATORY 

 APPARATUS. 



1. Diseases of Akteries and Veins. 



§ 210. Before entering on the pathological histology of the 

 vascular system, I must say a few words about its normal struc- 

 ture ; and this chiefly because current expositions of the subject 

 leave several disputed topics undecided; inasmuch however as 

 these ai'e most important for the due appreciation of morbid 

 changes, I feel bound to express my opinion concerning them at 

 the outset. 



As might have been anticipated a pnori, all the vessels of 

 the body are constructed on a uniform plan — which is best 

 elucidated by tracing the course of their development. 



Fig. 77. 



-J 



Let a — b represent a capillary loop, and a — ^ the boundary- 

 line of a growing organ. The blood flows from a to b under a 

 certain pressure, at a certain velocity, and with a certain 

 tension of the vascular walls. Let the pressure, the velocity 

 and the tension be each represented by unity. Now when the 



