ON THE BARLY STAGES OF INFLAMMATION 241 
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I have shown elsewhere,’ that in mammalia, as well as in amphibia, the 
blood remains fluid for days in the veins of an amputated healthy limb, though 
retaining its property of coagulating when shed.’ Its fluidity within the vessels 
is unaffected by free admixture of the atmosphere with it. For example, seven 
hours after injecting air into the veins of an amputated sheep’s foot, I found 
the frothy mixture contained in the vessels still quite fluid ; and the blood which 
formed the bubbles, coagulated when shed. Again, a human leg having been 
amputated above the knee, I pressed out the blood from about an inch of the 
open mouth of the popliteal vein, and covered the raw surface lightly with 
a damp cloth, so as to guard against drying of the blood, or of the walls of the 
vessel in contact with it. After the lapse of twenty-four hours, the vessel was 
still patulous ; but the blood, though it had been so long freely exposed to the 
influence of the air, continued perfectly fluid. Further, if a vein in an amputated 
sheep’s foot is simply wounded, no clot forms except at the seat of wound. 
If, however, a portion of any ordinary solid matter, such as a fragment of glass, 
a bit of clean wax, a hair, a needle, or a piece of fine silver wire, be introduced 
into such a vein, a deposit of fibrine takes place after some minutes upon the 
foreign body,* followed by coagulation of the blood in that particular part of the 
vessel ; the coagulum, however, never adhering to the vein, except at the lips 
of the wound.’ This shows that an ordinary solid possesses an attraction for 
1 See a paper by the author ‘On Spontaneous Gangrene from Arteritis and the Causes of Coagu- 
lation of the Blood in Diseases of the Blood-vessels’, Edinburgh Medical Journal, April 1858 (p. 69 
of this volume). The observations there recorded, and also the others mentioned in the text with regard 
to coagulation, have been made since the reading of the original manuscript. 
* The blood coagulates more slowly the later it is examined after death or amputation, and finally 
becomes altogether incapable of the process. The time when this occurs differs in different cases. Thus, 
in the foot of the sheep I have seen coagulation take place, though slowly, on the sixth day; but in 
the human subject on one occasion I found the blood remain permanently fluid when shed within forty- 
eight hours of death, though in another instance at the same period a soft clot formed in about halt 
an hour. 
* These facts, ascertained in November 1858, have considerably modified the views expressed in 
the paper above referred to. 
* From what has been stated in the text, it is evident that the ammonia theory of Dr. B. W. 
Richardson does not account for the fluidity or coagulation of the blood within the vessels. But the 
facts mentioned by that gentleman in the valuable essay which has gained the last Astley Cooper prize, 
and also my own experience [see the paper before referred to], have convinced me that a certain amount 
of the volatile alkali does exist in freshly drawn blood, and that it has the effect of retarding the process 
of coagulation. This principle must be borne in mind in all experiments upon this subject, in order 
to understand circumstances which would otherwise be inexplicable. Thus, if the foot of a sheep be 
obtained with the blood retained in the vessels by a bandage applied before the death of the animal, 
and, after reflexion of the skin, a needle be introduced into a vein by a free opening made by the scissors, 
a deposit of fibrine will be found upon it in perhaps five minutes ; but if the needle be pushed through 
the coats of such a vein, so as to introduce it without previous wound of the vessel, and allow little 
opportunity for escape of ammonia, the deposit will not take place for a quarter of an hour or more. 
Again, the blood obtained by wounding a vein immediately after reflecting the skin, within the first 
few hours after the death of the animal, takes a much longer time to coagulate than the blood shed from 
the same vessel after the lapse of half an hour or so; doubtless in consequence of escape of ammonia 
LISTER I R 
