NOVICE, OF FURTHER RESEARCHES ON THE 
COAGULATION OF THE BLOOD 
Read before the Medico-Chirurgical Society of Edinburgh, November 16, 1859. 
[Edinburgh Medical Journal, December 1859.] 
Mr. PRESIDENT.—I take this opportunity of demonstrating what appears 
to be a point of considerable importance with reference to the coagulation of 
the blood—a subject to which my attention has been again directed by the 
recurrence of that period of the Session in which the fundamental principles 
of pathology are discussed in a course of surgical lectures. 
I may remind the Fellows of this Society, that in a paper which I had the 
honour to read before them the Session before last,! I brought forward facts 
which seemed to prove that the ammonia theory does not apply to blood within 
the vessels of a living animal. That theory, as my hearers are doubtless aware, 
asserts that the fluidity of the blood depends upon the presence of a certain 
amount of free ammonia holding the fibrine in solution, and that coagulation 
is the necessary result of the escape of the volatile alkali. But it was shown 
in the paper referred to, that the blood, in man and other mammalia, though 
coagulating soon after death in the heart and great venous trunks, remains 
fluid for days in vessels of smaller size, and this under circumstances affording 
free opportunity for the escape of ammonia; and, on the other hand, that 
when a portion of a vessel either in an amputated limb or in a living animal 
is treated in a manner calculated to destroy its vital properties, the blood 
coagulates in the injured part, but retains its fluidity elsewhere, although there 
is no greater opportunity for the escape of ammonia in the one case than in 
the other. A striking instance of the difference between the natural receptacles 
of the blood and ordinary matter in their relations to the vital fluid happened 
to come under my notice this morning, in an arm which I amputated last evening 
at the shoulder-joint, on account of injury inflicted by machinery. On examin- 
ing the limb, which had lain undisturbed since the operation, I saw that the 
axillary vein, which was patulous at the part where it had been divided by 
the knife, contained some blood at a distance of about half an inch from the 
open orifice ; and having squeezed out a few drops, found that it was perfectly 
fluid, but yielded threads of fibrine when the point of a needle was drawn through 
it some minutes after emission. The blood had been for upwards of twelve 
* Vide Edinburgh Medical Journal, April 1858 (p. 69 of this volume). 
