TREATMENT OF INFLAMMATION. 181 



observation, has the following remarks on this sub- 



O 



ject : " Why it should happen that venous conges- 

 tions are never accompanied by an exudation of 

 blood-plasma, whilst arterial congestions are, is a 

 point that no one has yet endeavoured to explain. 

 To me it appears certain that all inflammatory 

 effusions occur through the capillary or interme- 

 diate vessels, and not in such vessels as may be 



properly called arteries or veins But it 



is scarcely possible to suppose that the mechanical 

 difference in the density of the filtrating membrane 

 should constitute the only distinction. It is im- 

 possible to reconcile the phenomena without having 

 recourse to some active vital power of attraction 

 between the blood and the parenchyma, as formerly 

 explained ; a power which, operating in the one case 

 and not in the other, causes different constituents of 

 the blood to become exuded. We are compelled, in 

 all our considerations of the subject, to go back to this 

 explanation as to an ultimate fact." Now, with re- 

 spect to the above-mentioned difference in the effects 

 of arterial and venous congestions, instead of endea- 

 vouring to explain its occurrence, I must dispute the 

 fact; for extreme and continued venous congestion 

 must necessarily be followed by capillary congestion ; 

 and if the lateral pressure of the blood detained in 

 these delicate porous vessels be sufficiently great, the 

 effusion or exudation of coagulating lyrnph will most 

 certainly take place. I have extracted the other 



* A Treatise on Inflammation as a Process of Anormal Nutrition, 

 p. 39. Edinburgh, 1844. 



N 3 



