Section of Medical Science. 511 



It appears, therefore, that in all arteries of such size as to admit 

 of measurement, and which supply inflamed parts, the only vital 

 powers of contraction, which experiments authorize our ascribing to 

 the coats of these vessels, is diminished during inflammation ; and it 

 may be safely added, that no other change but this diminution or 

 relaxation of contractile power has ever been perceived, either in 

 them, or in the smaller vessels which come under the observation of 

 the microscope, at least during the greater part, and in the highest 

 intensity, of inflammation. 



But if it be inferred from these facts that inflammation consists 

 merely in relaxation of vessels, giving an increased effect to the im- 

 pulse of blood from the heart to the part affected, several facts may 

 be stated to show that the explanation thus afforded is quite inade- 

 quate. The change which takes place on the movement of the blood 

 flowing to an inflamed part is, diminution of velocity or absolute 

 stagnation in the vessels most affected, combined with increased ve- 

 locity and increased transmission in all the neighbouring vessels ; 

 and it seems impossible to ascribe both these opposite effects to the 

 same cause, viz. a simple relaxation or loss of power in the vessels 

 concerned. Neither can the characteristic effusions consequent on 

 inflammation, and by which alone it is uniformly distinguishable from 

 simple congestion or serous effusion, (and particularly the increased 

 quantity and increased aggregation of the fibrin that exudes from 

 inflamed vessels,) be explained by this change of the action of the 

 vessels. And further, the local causes which excite inflammation are 

 not only such as in other instances produce an increase, instead of a 

 diminution, of vital power, but they are such as have been ascertained 

 to produce, when they are made to act on minute portions of indivi- 

 dual vessels only, contraction instead of relaxation ; as has appeared 

 in the experiments of Verschuir, Thomson, Hastings, Wedmeyer, and 

 others. 



The proper inference, therefore, appears to be, that the idea of an 

 increased action of vessels in an inflamed part is indeed a delusion ; 

 but that there is a really increased action within the vessels of the 

 part, i.e. an increased exertion of powers, by which the motion of 

 the blood is affected, but the action of which is independent of the 

 contractions of the living solids, and the effect of which is to cause 

 distention and relaxation of the vessels, within which they act with, 

 unusual energy. 



2. The immediate object of the experiments on death by asphyxia 

 was to ascertain whether the acceleration of the flowing blood 

 through the lungs, — which is undoubtedly produced by respiration, 

 and the failure of which appears, from the experiments of Williams 

 of Liverpool, and of Kay of Manchester, to be the immediate cause 

 of death by asphyxia, can be ascribed, as Haller and some very re- 

 cent authors have supposed, to the merely mechanical influence of 

 the alternate expansion and contraction of the lungs by the respi- 

 ratory movements. 



That this is not the fact might be concluded from the fatal as- 

 phyxia produced by breathing azote or other gases, not poisonous, 



