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Proceedings of Boycd Society of Edinburgh. [july 18 , 
coagulate. When shed from the body this condition is actively 
induced by its contact with foreign matter. It is unnecessary, there- 
fore, to assume that the vascular wall has any inhibitory power. 
In order conclusively to determine which view is the correct one, 
it is necessary to obtain blood which is neither in contact with the 
vascular wall nor with a solid foreign body This I have succeeded 
in doing by immersing drops of blood in fluids differing from it 
in surface tension, such as oil, paraffin, &c. 
Many experiments were made, notably the receiving of blood 
upon the greased surface of a mica plate immersed in a vessel full 
of paraffin oil. The drops remained fluid sometimes for two or three 
hours. The most successful experiments w T ere, however, performed 
by injecting a viscous mixture of vaseline and paraffin oil into the 
vein of a sheep. It was mixed with the blood so as to isolate 
drops of blood in the midst of the viscous mass. These remained 
fluid on more than one occasion for twelve hours afterwards. 
The conclusion I drew from these experiments was that blood 
required the influence of solid matter to bring about coagulation, 
and that the view of Sir Joseph Lister — which he had himself 
supported by the strongest arguments — was correct. 
Shortly after the completion of these experiments, the important 
results of Dr Freund’s were published. He had been traversing 
almost exactly the same ground that I had, and at the same 
time. 
There is a general belief that white blood corpuscles are con- 
stantly breaking down in the blood-vessels, setting free fibrin- 
ferment. This view we owe mainly to Alexander Schmidt and his 
school. Moreover, ferment when artificially injected into the blood- 
vessels soon disappears. 
I had been led by my experiments to the fact that the smallest 
quantity of fibrous ferment will in time coagulate a considerable 
mass of blood, and inasmuch as blood remains fluid in a ligatured 
vein for twelve or twenty-four hours, it is improbable that blood 
corpuscles are constantly breaking down and setting free ferment, 
unless we suppose that its action is prevented by the vascular wall. 
This latter supposition both Freund’s and my own experiments 
have shown to be highly improbable. 
In order by a direct experiment to determine whether the vascular 
