130 ON THE COAGULATION OF THE BLOOD 
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 investiga- 
tion, which showed not only abundant white corpuscles, but also several isolated 
red ones that had not subsided. This observation was made three hours after 
the death of the horse, but I obtained essentially similar results on repeating 
the experiment in another horse an hour after death; so that there can be 
no doubt whatever that the fibrine was in the same condition as it is in the 
blood-vessels of a living animal. The observation appears also particularly 
satisfactory on this account, that the liquor sanguinis was not separated from the 
corpuscles by any process of transudation through the walls of the blood-vessels, 
which might be conceived to involve retention of some constituent of the lquid, 
which, though in solution, might be unable to pass through their pores, but 
simply by the subsidence of the corpuscles, which must have left all the materials 
of the hquor sanguinis behind them. Hence it is proved beyond question that 
if the hquor sanguinis could be separated completely from the blood-corpuscles 
it would resemble the fluid of hydrocele in being incapable of coagulation when 
shed into a cup. 
Now this struck me as a very satisfactory and beautiful truth, inasmuch 
as it clears away all the old mystery of the distinction between inflammatory 
exudations and dropsical effusions. Dropsical effusions, exhibiting little dis- 
position to coagulate, have been supposed to consist almost exclusively of 
serum, and the exudation of the entire liquor sanguinis has been regarded as 
the special characteristic of inflammation; and very unsatisfactory theories 
have been put forward by ingenious pathologists to account for this difference. 
But it now appears that a dropsical effusion, like that of hydrocele, is undis- 
tinguishable from pure liquor sanguinis. 
Various dropsical effusions have been lately investigated with reference to 
their coagulability on the addition of blood-corpuscles by Dr. Schmidt of 
Dorpat, who finds that while they differ from one another in the amount of 
water they contain (just as is the case with serum filtered artificially through 
animal membranes under different degrees of pressure), yet they are all but 
universally coagulable. Schmidt has also carried the investigation further. 
He has found that by chemical means he can extract from the red corpuscles 
a soluble material which, when added to these exudations, leads to coagulation. 
