ON THE COAGULATION OF THE BLOOD 133 
inducing a mutual reaction between its solid and fluid constituents, in which 
the corpuscles impart to the liquor sanguinis a disposition to coagulate. This 
reaction is probably simply chemical in its nature, yet its product, the fibrine, 
when mixed with blood-corpuscles in the form of an undisturbed coagulum, 
resembles healthy living tissues in being incapable of that catalytic action 
upon the blood which is effected by all ordinary solids, and also by the tissues 
themselves when deprived of their vital properties. 
These principles have, of course, very extensive applications to the study 
of disease, but I must content myself with alluding very briefly to inflammation, 
the most important of all pathological conditions. 
If we inquire what is the great peculiarity of inflamed parts in relation 
to the blood as examined by the naked eye, we see that it consists in a tendency 
to induce coagulation in their vicinity—implying, according to the conclusions 
just stated, that the affected tissues have lost for the time being their vital 
properties, and comport themselves like ordinary solids. Thus, when an artery 
or vein is inflamed, coagulation occurs upon its interior, in spite of the current 
of blood, precisely as would take place if it had been artificially deprived of its 
vital properties. On one occasion I simulated the characteristic adherent clot 
of phlebitis by treating the jugular vein of a living sheep with caustic ammonia, 
and then allowing the circulation to go on through the vessel for a while, when, 
on slitting it up, I found its lining membrane studded with grains of pink fibrine 
which could be detached only by scraping firmly with the edge of a knife. Again, 
comparing an inflammatory exudation into the pericardium or into the inter- 
stices of the cellular tissue with dropsical effusions into the same situations, we 
are struck with the fact that, while the liquor sanguinis effused in dropsy remains 
fluid, the inflammatory product coagulates. Now we know that in intense 
inflammation the capillaries are choked more or less with accumulated blood- 
corpuscles, which must cause great increase in the pressure of the blood upon 
their walls; and from what we know of the effect of venous obstruction in 
causing dropsical effusion of liquor sanguinis through increased pressure, we are 
sure that we have in the inflammatory state the physical conditions for a similar 
transudation of fluid through the walls of the capillaries. And the natural 
interpretation of the difference in the two cases as regards coagulation seems 
to be, that whereas in dropsy the fluid is forced through the pores of healthy 
vessels, in inflammation the capillary parietes have lost their healthy condition, 
and act like ordinary matter; so that the liquor sanguinis, having been sub- 
jected, immediately before effusion, to the combined influence of the injured 
tissue and the blood-corpuscles, has acquired a disposition to coagulate, just 
like the buffy coat of horses’ blood shed into a glass, or like the frog’s liquor 
