1gO ON THE COAGULATION OF .THE BLOOD 
assuming the condition of a delicate network of rouleaux, they become aggre- 
gated into dense spherical masses, often visible to the naked eye, like coarse grains 
of sand ; and these densely aggregated corpuscles, falling more quickly than the 
rouleaux in the liquor sanguinis, as hailstones fall more rapidly than snow- 
flakes, soon leave the upper part of the fluid comparatively free from corpuscles ; 
so that within about half an hour the upper third, or it may be half, of the blood 
is a transparent liquid.!’ When I had ascertained through the translucent walls 
of the vein that this state of things had occurred, I punctured the upper part of 
the vessel, so as to let out some of the clear fluid, and found that it was very 
slow in coagulating. In about three-quarters of an hour it had only begun to 
coagulate, whereas a little of this same clear fluid, to which a small portion of 
coagulated blood was added, clotted in a very short period. That the clear 
fluid did coagulate at all was sufficiently explained by microscopical examina- 
tion, which showed that there were present in it some red corpuscles and 
numerous white corpuscles. It was obvious that if we could have separated 
the corpuscles absolutely from the liquor sanguinis, there would have been no 
coagulation at all; and as the separation of the corpuscles from the plasma 
had occurred, not by transudation through vascular walls but simply as the 
result of gravity, it could be no longer doubted that Schmidt’s conclusions were 
essentially right. 
During the time that has since elapsed various endeavours have been made 
to ascertain the precise nature and mutual relations of the constituents of the 
liquor sanguinis and the corpuscles thus concerned in the formation of the fibrine. 
This inquiry cannot be said to be yet terminated, and it is, at the present time, 
uncertain whether Schmidt’s simple original view may not be correct, that there 
are two albuminoid substances, one in the plasma and one in the corpuscles, 
which combine to constitute fibrine. 
These investigations, most valuable as they are, have, as it seems to me, 
somewhat overshadowed the question, which is after all the most interesting 
to us as practitioners, namely, What are the circumstances that determine the 
mutual reaction of these two constituents ? What are the conditions under 
which the corpuscles are induced to give up their element of the fibrine, to combine 
with the element in the liquor sanguinis ? This subject engaged a large share 
of my attention many years ago; and, though I am afraid I have not much of 
novelty to communicate regarding it, yet in consequence of its very great impor- 
‘ The same thing is seen in the mixture of serum and corpuscles obtained by stirring the blood 
during coagulation. In that from the horse the red corpuscles subside from about the upper third of 
the liquid within half an hour; whereas that from the ox shows only a thin layer of serum after the 
lapse of twenty-four hours. I am surprised to see that in some textbooks the buffy coat is attributed 
to slowness of coagulation. 
