108 FURTHER RESEARCHES ON COAGULATION OF THE BLOOD 
‘Mr. Lister now proceeded to perform a similar experiment before the 
Society. A glass containing some liquor sanguinis of the horse’s blood, shed 
twenty-nine hours before, was taken out of the mixture of ice and water in 
which it stood, and the contents were seen to be still to a considerable extent 
fluid, although acidulated with acetic acid two hours previously. A portion of 
the liquid was poured into a watch-glass, and, having been shown to be acid by 
litmus paper, was set aside to coagulate, and about a quarter of an hour later 
was exhibited as a soft clot. Mr. Lister then continued :—] 
From these facts it is obvious that the ammonia theory utterly fails to 
explain the influence of temperature on coagulation. The circumstance that 
the liquor sanguinis was acid in this experiment is clear proof that it contained 
no free ammonia whatever, yet the acidulated plasma was affected by cold 
and heat, just like ordinary blood. It remained fluid near the freezing-point, 
although the ammonia it originally contained must have entered into com- 
bination and lost its reputed power of dissolving the fibrine, and it coagulated 
when warmed, though the ammonia, fixed by the acid, must have been incapable 
of evolution. If the author of the ammonia theory were asked to explain why 
this horse’s blood took a quarter of an hour to coagulate, he would no doubt 
reply that it must have contained a large amount of ammonia, requiring all 
this time to escape. But we have seen that the acid liquor sanguinis, though 
possessing no free ammonia at all, took as long to clot. There can therefore 
I think be little question but that the slowness of coagulation in the horse, 
compared with the rapidity of the process in the sheep, and the variations met 
with in the period in the human species, depend not on the amount of ammonia 
present in the blood, but on differences in its other constituents, and, speaking 
generally, that the theory which attributes the coagulation of the blood to the 
escape of ammonia is fallacious." 
* Since the above communication was made, I have seen for the first time the able essay of 
Dr. E. Briicke, which competed for the Astley Cooper Prize (see Med.-Chir. Review, vol. xix); and 
I find that the principle which he advocates—viz. that the fluidity of the blood within the living body 
depends upon an action of the walls of the vessels upon it—is supported by many facts which he has 
observed in the chelonian reptile, very similar to what I have made out in mammalia. Thus, he found 
that the blood remained fluid in the heart of the turtle for days after death, and for several hours after 
he had blown air through the veins of the neck, so as to make a foamy mixture in the cavities of the 
organ. He also found, as had been previously ascertained by Virchow and others, that after the intro- 
duction of mercury into the heart the blood coagulated about the globules of the metal, but not 
elsewhere, and this he regarded as an example of the influence of ordinary matter in inducing coagula- 
tion in its vicinity. He also succeeded with the following very striking experiment, which would not have 
answered with mammalia: he drew blood into a cup from the veins of a living turtle, and injected it 
into the empty heart of another turtle just killed, and found that the blood remained fluid for several 
hours in its new situation, instead of coagulating in a few minutes as when retained in a cup.—J. L. 
