ON THE COAGULATION OF THE BLOOD 129 
the properties of the vessel by its presence; so that the previous coagulation 
must be attributed not to any loss of power in the vein but simply to the action 
of the foreign solid. 
In seeking for an analogy to this remarkable effect of ordinary solids upon 
the blood, we are naturally led to the beautiful observations of Professor Graham, 
lately published in the Philosophical Transactions. He has there shown what 
insignificant causes are often sufficient to induce a change from the fluid or 
soluble to the ‘ pectous’ or insoluble condition of ‘ colloidal’ forms of matter. 
Indeed, Mr. Graham has himself alluded to the coagulation of fibrine as being 
probably an example of such a transition. 
There is, however, another remarkable circumstance that must be taken 
into consideration, of which I myself have been only recently aware, and which 
may be new to several Fellows of the Society ; and that is, that in spite of the 
influence of an ordinary solid the liquor sanguinis is not capable of coagulating 
per se. It was observed many years ago by my colleague, Professor Andrew 
Buchanan, of Glasgow, that the fluid of a hydrocele, generally regarded as mere 
serum, coagulated firmly if a little coagulum of blood diffused in water was 
added to it—an effect which he was disposed to attribute to the agency of the 
white corpuscles. I repeated Dr. Andrew Buchanan’s observations last year, 
and satisfied myself first that the diffused clot did not act simply by providing 
solid particles to serve as starting-points for the coagulating process. I tried 
various different materials in a finely divided state, and found that none of 
them, except blood, produced the slightest effect. But I found that if a mixture 
of serum and red corpuscles from a clot was added to some of this hydrocele- 
fluid, it was soon converted into a firm solid mass. If a small quantity of the 
serum and corpuscles was dropped into the fluid and allowed to subside without 
stirring, coagulation rapidly took place in those parts where the red corpuscles 
lay, while other parts of the fluid remained for a long time uncoagulated. This 
seemed to indicate that the red corpuscles had a special virtue in inducing the 
change. I confess, however, that till very lately I was inclined to suppose 
that in the hydrocele-fluid the fibrine must be in some peculiar spurious form. 
We know that the buffy coat of the horse’s blood coagulates in a glass without 
addition of clot, and we know that lymph coagulates, so that I did not doubt 
that liquor sanguinis would always undergo the change when influenced by 
ordinary matter. But an observation which I made not many days ago shows 
that this was a mistake. I obtained the jugular vein of a horse, and having 
kept it for a while in a vertical position till I could see through its transparent 
coats that the red corpuscles had fallen from the upper part, I removed all 
* Proceedings of the Glasgow Philosophical Society, February 19, 1845. 
LISTER I Kk 
