ON THE COAGULATION OF THE BLOOD 
INU TTS PRACTICAL ASPECTS 
The Annual Oration to the Medical Society of London, delivered May 4, 1891. 
[British Medical Journal, 1891, vol. i, p. 105.] 
Mr. PRESIDENT AND GENTLEMEN.—Thirty years ago, Dr. Alexander 
Schmidt, of Dorpat, enunciated a totally new view of the coagulation of the 
blood. Having rediscovered the fact observed many years before by Dr. Andrew 
Buchanan, of Glasgow,’ that hydrocele fluid—uncoagulable in itselfi—is made 
to coagulate by the addition to it of the serum of blood already coagulated, and 
pursuing extended researches in the line thus indicated, he came to the conclusion 
that fibrine does not exist as such in solution in the plasma, but is composed of 
two albuminoid substances, one present in the liquor sanguinis, to which he gave 
the name of fibrinogen, and the other a constituent of the blood-corpuscles, 
and this he termed the fibrinoplastic substance.” 
It might be objected to Professor Schmidt that the hydrocele fluid and the 
various dropsical effusions with which he had worked were not fairly comparable 
to liquor sanguinis ; that they were transudations through the walls of vessels, 
and that the liquor sanguinis might have become in one way or another altered 
in the process of transudation. This objection was, as I believe, removed by 
an observation made by myself about the same period.*? It had fallen to my 
lot to observe that in mammalia, whereas the blood usually coagulates soon 
after death in the heart and the main vascular trunks, in the secondary vessels 
it remains fluid for an indefinite period, and that not only in those of small 
calibre, but, if the animal be large, in large vessels also. This being understood, 
I proceeded as follows : Having removed a portion of the jugular vein of a horse 
with the blood contained in it, between two ligatures, I suspended this segment 
of the vein in a vertical position. In the blood of the horse, the red corpuscles 
behave in a totally different manner as regards their aggregation from those 
of a healthy man or of the ox. In the horse, instead of the red corpuscles 
1 Proceedings of the Glasgow Philosophical Society, February 19, 1845. 
* Archiv fiir Anat. Phys., &c., 1861 and 1862. 
3 The Croonian Lecture, by the author, ‘On the Coagulation of the Blood,’ Proceedings of the Royal 
Society, 1863, p. 606 (page 109 of this volume). 
