iN Tas PRACTICAL ASPECTS IgI 
tance, I have thought that it might perhaps be not unworthy of the circum- 
stances in which the kindness of your Council has placed me this evening. 
Shortly before my investigations began, Professor Briicke, of Vienna, had 
conducted an inquiry into the conditions which determine coagulation, and had 
arrived at conclusions which to a certain extent resembled those to which I was 
led.t. He found, as I also did, that there is a world-wide difference, in their 
relations towards the blood, between the walls of the living vessels and ordinary 
solid matter ; and Briicke concluded, as Sir Astley Cooper and others had done 
before him, that this difference consisted in an active state of the living vessels ; 
that the blood-vessels, by an action which they exerted upon the blood, prevented 
it from coagulating. My investigations, on the other hand, led me to conclude 
that healthy blood has no spontaneous tendency to coagulate ; and that the 
walls of the blood-vessels are not active, as Briicke supposed, but passive in their 
relation to coagulation ; that ordinary solids induce coagulation by an attractive 
influence—comparable, perhaps, to that which a thread exerts in causing the 
deposition of sugar-candy from a solution of sugar—while the healthy living 
tissues differ from ordinary solids in being destitute of this attractive influence. 
Out of many experiments tending to this influence, published long ago,’ 
I may be permitted again to describe one which not only appears to me conclusive 
on the point at issue, but is also of interest otherwise. A portion of the jugular 
vein of an ox with the blood in it being held vertically, I cut off the upper end, 
taking scrupulous care that the wounded part of the vessel did not come in contact 
with the blood, and then passed down into the vein a tube composed of very 
thin glass of a calibre rather less than that of the jugular vein, its upper end 
being stopped by a perforated cork in which was inserted a narrow glass tube, 
which again was continued with a short piece of vulcanized india-rubber tubing. 
The tube was pressed with the utmost steadiness down into the vein, so as to 
disturb the blood as little as possible. In the course of time, the vein being 
a little squeezed, blood made its appearance in the narrow glass tube, and then 
at the end of the india-rubber tube. When this was the case, the india-rubber 
tube was secured by a clamp, and the whole apparatus was rapidly inverted, and 
the piece of vein withdrawn. Waterproof tissue was then tied over the open 
end of the large tube to prevent evaporation and exclude dust, and the tube 
was securely fixed and left undisturbed. Thus we had blood present in a 
vessel consisting entirely of ordinary solid matter, but having been subjected 
in a minimum degree to the influence of the ordinary solid: and the result was 
that when I came to examine the blood after the lapse of ten hours, I found it 
' British and Foreign Medical Review, 1857. 
* The Croonian Lecture, Proceedings of the Royal Society, loc. cit. 
