220 PRACTICE OF PHYSIC. 



the congestions which occur, and the haemorrhagy, do not de- 

 pend upon a general, but, as I have said they often do, upon 

 a topical plethora, in consequence of a particular constitution. 

 It is alleged, that in such cases exercise may be hurtful. I 

 have just now said, that every increase of motion does affect 

 a particular determination. If now the congestion has taken 

 place, and is in danger by the smallest excess of being brought 

 to its last effect, a haemorrhagy, then I own that bodily 

 exercise is a dangerous measure ; but if we can come before 

 that period, before the determination and accumulation is con- 

 siderable, then these may be obviated by the exercise. This 

 depends upon the remarkable principle, that the increased 

 action of the heart and arteries does not exert its influence 

 equally upon all parts of the system, but is determined more es- 

 pecially to the surface f the body. And although exercise may 

 sometimes increase particular internal determinations, and, for 

 instance, bring on haemoptysis in a man who is liable to it, and 

 raise it to its utmost height ; yet, even in the case of the lungs, 

 its effects are quite different, if it is used before the determina- 

 tion is fully fixed."" 



DCCLXXXVII. Artificial evacuations may be employed 

 to diminish the plethoric state of the body ; and when, at any 

 time, it has become considerable', and immediately threatens a 

 disease, these evacuations should be made to the quantity that 

 the symptoms seem to require. But it is constantly to be at- 

 tended to, that blood-lettings are improperly employed to 

 prevent a plethora, as they have a tendency to increase it 

 (DCCXXI.) ; and as they require to be often repeated, and 

 are thereby apt to induce a habit which may be attended with 

 much danger. 



" Yet, when a plethoric congestion can be manifestly observed 

 to be already formed, and threatening haemorrhagy, 1 venesection 

 is certainly absolutely necessary ; and, upon several occasions, 

 even its repetitions may be. And it is possible, that it may 

 be practised with impunity and with advantage, if other means 

 are employed to concur with it in obviating plethora. The man- 

 agement which I should propose, and which I have found on 

 many occasions useful, is this : when there was a manifest pletho- 

 ric state, and I had found occasion for bleeding, I watched over 



