226 ON THE NATURE AND PRINCIPLES OF 



The results of medical practice here harmonise very 

 beautifully with some experimental observations (re- 

 lated in Magendie's Journal), in which, on exposing 

 and irritating a fold of mesentery, the redness caused 

 by the enlargement and distension of the peritoneal 

 vessels rapidly disappeared when free effusion took 

 place from the adjacent mucous membrane. And 

 the mode of action of all other derivatives, such as 

 leeches, cupping, blisters, &c., in relieving the en- 

 gorgement of the affected vessels, is precisely similar. 

 If, however, any considerable quantity of blood or 

 serum be thus abstracted, it will, of course, in addi- 

 tion to its local action, also tend to diminish the 

 general pressure of the arterial blood. It is scarcely 

 necessary to add, that effusion as a derivative agent 

 is admissible only in situations where the arrange- 

 ment of the vessels is such as to allow of a free 

 discharge and ready removal of the extravasated 

 matters: in the use of counter-irritants we are 

 therefore necessarily restricted to the skin and 

 mucous membranes. 



Having thus reviewed the operation of the re- 

 medies calculated to relieve that" local disorder of 

 the circulation which constitutes the essence of in- 

 flammation, we have in the next place to consider 

 the means by which the removal of the immediate 

 effects of that disease is accomplished. But, before 

 entering upon this subject, it may be observed, that 

 we occasionally have it in our power to prevent, or 

 at least limit, by the direct application of mechunir.il 

 support, the escape of the compressed fluid through 

 the coats of the distended vessels. Effusion, as 



