H^EMORRHAGIES. 213 



lated in the veins, from any interruption of its proper course, 

 .that accumulation must resist the free passage of the blood from 

 the arteries into the veins. This again must produce some con- 

 gestion in the extremities of the red arteries, and therefore some 

 increased action in them, which must be determined with more 

 than usual force, both upon the extremities of the arteries, and 

 upon the exhalants proceeding from them ; and this force may 

 occasion an effusion of blood, either by anastomosis or rupture. 



DCCLXX. In this manner I apprehend the haemorrhoidal 

 flux is to be explained, so far as it depends upon the state of the 

 whole system. It appears most commonly to proceed from the 

 extremities of the haemorrhoidal vessels, which, being the most 

 dependent and distant branches of those veins that form the 

 vena portarum, are therefore the most readily affected by every 

 accumulation of blood in that system of veins, and consequent- 

 ly by any general plethora in the venous system. 



DCCLXXI. It is here to be observed, that I have spoken 

 of this hsemorrhagy as proceeding from the haemorrhoidal ves- 

 sels only, as indeed it most commonly does ; but it will be 

 readily understood, that the same accumulation and resistance 

 to the venous blood, may, from various causes, affect many of 

 the extremities of the vena portarum, which lie very superfi- 

 cially upon the internal surface of the alimentary canal, and give 

 occasion to what has been called the Morbus niger or Melocna. 



DCCLXXII. Another part in which an unusually plethoric 

 state of the veins may have particular effects, and occasion hse- 

 morrhagy, is the head. In this, the venous system is of a pe- 

 culiar conformation, and such as seems intended by nature to 

 give there a slower motion to the venous blood. If, therefore, 

 the plethoric state of the venous system in general, which seems 

 to increase as life advances, should at length increase to a great 

 degree, it may very readily affect the venous vessels of the head, 

 and produce there such a resistance to the arterial blood, as to 

 determine this to be poured out from the nose, or into the ca- 

 vity of the cranium. The special effect of the latter effusion 

 will be, to produce the disease termed Apoplexy ; and which, 

 therefore, is properly named by Dr. Hoffmann, Hcemorrhagia 

 Cerebri : and the explanation of its cause, which I have now 

 given, explains well why it happens especially to men of large 



