THE CAUSES OF COAGULATION OF THE BLOOD 83 
inflammation. Some of the exuded matter had trickled down on a board 
beneath, and had there coagulated, showing that genuine exudation of lymph 
had been the result of this post mortem inflammation, then, I believe, for the 
first time observed in one of the mammalia.’ I cannot avoid expressing the 
satisfaction that it has given me to find what I had inferred from other cir- 
cumstances, in my investigations on inflammation, now established as a matter 
of observation. I had found that the blood-corpuscles, both red and white, 
were perfectly free from adhesiveness within the vessels of a healthy part, but 
that in an inflamed region they stuck together just as they are seen to do between 
two plates of glass. Having thus observed that the corpuscles of the blood 
comport themselves in an inflamed part in the same manner as in blood drawn 
from the body, I inferred that the liquor sanguinis was, in all probability, 
similarly affected, although coagulation is not observed in the capillaries, in 
consequence of the movement of the blood; and I gave the same explanation 
of the speedy coagulation of lymph, and of the formation of clots in inflamed 
vessels, as has been substantiated by independent facts this evening. In the 
paper before alluded to, the following passage occurs :—‘ The non-adhesiveness 
of the red and white corpuscles, and the fluidity of the blood, seem to be due 
to one and the same mysterious and wonderful agency—the tissues of a healthy 
body appearing to extend over the blood near them, a part of the same influence 
by which they are themselves protected from the action of chemical affinities 
tending to their decomposition.” We now see that when an agent capable of 
producing inflammation acts upon a part in which the blood is at rest, 
coagulation of the blood does really occur in the vessels. 
There is an error of observation into which Dr. Richardson has un- 
accountably fallen, which it appears important to correct. In speaking of the 
coagulation of a portion of blood enclosed between two ligatures in the jugular 
vein of a dog or cat, he mentions the formation of a large bubble of air within 
the vessel, a little prior to the occurrence of coagulation. I have frequently 
seen the pellucid appearance he describes, but find that it is in no way con- 
nected with coagulation, but is due to the subsidence of the red corpuscles, 
leaving a layer of clear liquor sanguinis at the top. If two ligatures be applied, 
about an inch apart, upon a subcutaneous vein of one of the legs of a cat, care 
having been taken not to disturb the connexions of the vessel, or inflict injury 
upon it, and the leg be suspended by the paw in the vertical position, the clear 
appearance will begin to show itself below the upper ligature within five minutes. 
1 Tension upon the blood in the vessels, resulting from the bandage, supplied, I imagine, the place 
of the force of the heart in squeezing out the liquor sanguinis through the walls of the capillaries, de- 
prived of their usual power of retaining it. 
G2 
