RESEARCHES ON THE COAGULATION OF THE BLOOD. 105 
no free ammonia whatever; yet the acidulated plasma was 
affected by cold and heat, just like ordinary blood. It re¬ 
mained fluid near the freezing point, although the ammonia 
it originally contained must have entered into combination 
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, speak¬ 
ing generally, that the theory which attributes the coagulation 
of the blood to the escape of ammonia is fallacious.*— Edin. 
Medical Journal. 
* “ Since the above communication was made, I have seen for the first 
time the able essay of Dr. E. Briicke, which competed for the Asfley 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 introduction 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 coagulation in its vicinity. He also succeeded with the 
following very striking experiment, which would not answer 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.” 
XXXIII. 
14 
