270 PRACTICE OF PHYSIC. 



happens to both sexes, and to persons of all ages, from causes 

 which do not affect the system, and are manifestly suited to 

 produce a topical affection only. 



" The case of venous congestion, connected more generally 

 with the system, we find to be a plethoric state of the vena 

 portarum, the cause of which we readily perceive, on consider- 

 ing that the venous blood here takes a particular course in its 

 return from several veins, to be again distributed through the 

 liver, where it has not the assistance of muscular action, and 

 from thence appears to move slower than in any other part. 

 Now, after a certain period of life, when the balance is thrown on 

 the side of the veins, an accumulation of blood takes place in the 

 system of the vena portarum, and more particularly in persons 

 of flaccid bodies, of a sedentary life, melancholic temperament, 

 and full living. The operation of all these causes in produc- 

 ing the plethoric state in the vena portarum, is very well under- 

 stood among physicians ; but it is not as much attended to as 

 it ought, that in consequence of that plethoric state a consid- 

 erable resistance arises in the extremities of these veins every 

 where, and in the haemorrhoidal veins in particular, producing 

 the haemorrhoidal flux. But the same causes may act upon the 

 other extremities of the vena portarum besides the haemorrhoi- 

 dal. Accordingly we find the effects of this plethoric conges- 

 tion operating on the spleen and pancreas : but we may expect 

 it to act more on those extremities which are most numerous, 

 those which terminate on the whole internal surface of the ali- 

 mentary canal; and, accordingly, dissections have shewn fre- 

 quent instances of effusion of blood on the internal surface of 

 the alimentary canal, in a great measure resembling the haemorr- 

 hoidal tumours and flux ; for, on the surface of the canal also, 

 vessels are ruptured, and occasion an effusion into the cavity of 

 the intestine. It is this that so frequently exhibits to us the 

 atra bills of the ancients. The effusion which I have explain- 

 ed, will account for the black petechiae and grumous blood, so 

 frequently found in the course of the alimentary canal; 

 and we can easily understand, that when blood is effused, 

 the coagulable lymph will concrete with the red globules, 

 and the thinner fluid being washed away, we find the re- 

 mainder of various consistence. I observe all this to take 



