82 ON SPONTANEOUS GANGRENE FROM ARTERITIS AND 
almost universal occurrence of coagulum in the heart of the human subject 
twenty-four hours after death, compared with the universal absence of it in 
the small veins of healthy parts, so far as I have yet examined them, both 
in man and the lower animals, I think the fact must be admitted, that where 
a large mass of blood exists within a cavity of the heart or a blood-vessel, it 
experiences coagulation sooner than if in a small vessel of the same body. If 
this be admitted, it becomes a strong argument in favour of the active operation 
of the tissues, for the blood is more exposed to the influence of the air in a sub- 
cutaneous vein than in the heart, and the only conceivable reason for the 
greater persistence of fluidity in the latter than in the former is that the 
influence of the tissues operates to greater advantage upon the smaller mass 
of blood. 
Again, supposing it to be admitted that free ammonia exists within the 
blood-vessels, maintaining the fibrine in solution, a hypothesis which, I confess, 
appears to me very probable,—granting the ammonia theory, I say, as far as 
it can possibly be granted, it is clear that no merely neutral action of the tissues 
could check the evolution of the alkali in the manner above described ; and 
nothing can tend to convince us more of the potency of the vital forces than 
to consider what new powers must be impressed upon the chemically inert 
constituents of the tissues, in order to enable them securely to chain down 
the alkaline gas, in spite of its excessive volatility. 
There is one other experiment upon the sheep’s foot which I do not like 
to omit mentioning. Having exposed a subcutaneous vein, six hours after the 
death of the animal, I pressed out the blood from an inch of it, and treated 
the empty part with caustic ammonia, the adjacent parts being protected by 
olive oil. When the smell of ammonia had passed off, I let the blood return, 
and, two or three hours after, found that the portion which had had its vitality 
destroyed by the ammonia, was full of clot, while the blood in the adjacent 
parts of the vein was fluid, and coagulated on exposure.! 
This, however, was not the only result of the application of the ammonia. 
The surrounding tissues had not been thoroughly protected from its action 
by the oil, and next morning all the parts on which it had acted were the seat 
of the most intense congestion, accompanied with exudation of glairy matter into 
the cellular tissue ; in fact, there were all the appearances of the most severe 
* Two feet of a sheep, killed six hours before the Society met, were exhibited in illustration. One 
of these was prepared in the manner described in the text. The portion of vein which had been treated 
with ammonia contained a cylindrical coagulum, while the blood in the adjacent parts of the same 
vessel was fluid. The other foot was for the purpose of showing the fluidity of the blood so many hours 
after death. A considerable amount having been shed into a saucer in the liquid state, soon assumed 
the solid form. 
ter 
