68 SYMPTOMS OF INFLAMMATION. 



now endeavour to explain the views of the old and of the new 

 school of therapeutics, upon this important point. 



The Old View. — Of all antiphlogistic remedies, the most 

 important was blood-letting; and the effect of general blood- 

 letting in arresting inflammation was said to be owing princi- 

 pally to its lessening the force of the heart's action, causing 

 derivation of the blood from the part, and facilitating the action 

 of other remedies. " A sedative result on the heart's action is 

 effected by withdrawing from the central organ of circulation a 

 part of its natural stimulus, the blood, by which its action is 

 habitually maintained, and partly by the intervention of an im- 

 pression produced on the nervous system ; it being well known 

 that the sudden diminution of pressure on the brain and medulla 

 oblongata has a remarkable effect in diminishing the frequency 

 and force of the heart's action." 



Dr. Alison says : — " The effect of blood-letting in causing 

 derivation from parts actually inflamed to other parts of the 

 body has not been studied with so much care as might have 

 been expected from the pains bestowed upon it by Haller. 

 Whether this effect is, as he thought he had ascertained, in- 

 explicable on merrely mechanical principles ; or whether, as 

 Magendie and Poisenille assert, it is merely the effect of the 

 contractile power of the vessels, and the forced state of disten- 

 sion in which they exist during life, causing a flow to any 

 point where an opening is made; it is quite certain that a 

 movement in that direction is immediately perceived in all the 

 small vessels that can be seen under the field of the microscope, 

 on a puncture being made in any one of them ; and in Haller's 

 observations it distinctly appeared that this movement often 

 inverted the natural course of the circulation, and often extended 

 to blood stagnating in vessels, and caused globules to separate, 

 and become distinct, which had previously combined in irregular 

 masses. This being so, it cannot be doubted that similar changes 

 must be effected, in a greater or a less degree, in the blood stag- 

 nating in inflamed parts, when an exit is given to the blood from 

 other parts of the cu^culatory system, whether by general or local 

 blood-letting. And it does not seem possible to understand on 

 what other principle than this blood-letting can be useful, as 

 it undoubtedly is, in certain cases of inflammation, chiefly ab- 

 dominal, when the pulse is smaller and even feebler than 



