COAGULATION OF THE BLOOD. 
549 
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. And rew Buchanan’s observations last year, and satisfied 
myself first that the diffused clot did not act simply by pro¬ 
viding 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 cor¬ 
puscles 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 in¬ 
dicate 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 fibrin 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 bloody tissue from 
that part of the vein, and punctured it so as to let out the 
liquor sanguinis into a glass. Finding after eighteen minutes 
that the liquid had not begun to coagulate, I added a drop 
of serum and corpuscles to a portion of it, and within seven 
minutes there was a clot wherever the corpuscles lay, whereas 
the rest of the fluid was still very imperfectly coagulated after 
another half hour had elapsed. That the liquor sanguinis to 
which no addition had been made coagulated at all, was 
sufficiently explained by microscopic investigation, which 
showed not only abundant white corpuscles, but also several 
isolated red ones that had not subsided. This observation 
* ‘ Proceedings of the Glasgow Philosophical Society,’ February 19 th, 
1845 . 
