COAGULATION OF THE BLOOD. 
317 
Both these notions, however, have since been swept away. 
In the first place, I have observed recently that it is by no 
means only in small vessels that the blood remains fluid after 
death. If blood be retained within the jugular vein of a 
horse or ox by the application of ligatures, either before or 
after the animal has been struck with the poleaxe, it will 
often continue fluid, but coagulable, in that vessel, which is 
upwards of an inch in diameter, for twenty-four or even 
forty-eight hours after it has been removed from the body. 
I say often, but not always. The jugular vein seems to be 
in that intermediate condition, between the heart and the 
small vessels, in which it is uncertain whether it will retain 
its vital properties for many hours, or will lose them in the 
course of one hour or so. Unfortunately for my present 
purpose, it happens that in this jugular vein, removed from 
an ox six hours ago, coagulation has already commenced, as 
I can ascertain by squeezing the vessel between my fingers. 
But now that I lay open the vessel, you observe that the 
chief mass of its contained blood is still fluid, and we shall 
at all events have an opportunity of seeing that what is now 
fluid will in a short time be coagulated. It is an interesting 
circumstance, with reference to the question which we are 
now considering, that the coagulation always begins in con¬ 
tact with the vein, indicating that it is not the wall of the 
vessel that keeps the blood fluid, but that, on the contrary, 
the wall of the vessel, when deprived of vital properties, 
makes the blood coagulate. 
The observation of the persistent fluidity of the blood in 
these large vessels furnished the opportunity of making a 
very satisfactory experiment which I hoped to have exhibited 
before the society, but as there was some clot in the vein I 
did not think fit to run the risk of failure. The experiment 
is performed in the following way. A piece of steel wire is 
wound spirally round one of the veins in its turgid condition, 
and with a needle and thread the coats of the vessel are 
stitched here and there to the wire, care being taken to avoid 
puncturing the lining membrane, and thus the vessel is 
converted into a rigid cup. Two such cups being prepared, 
and the lining membrane of the vein being everted at the 
orifice of each, so as to avoid contact of the blood with any 
injured tissue, 1 found that, after pouring blood to and fro 
through the air in a small stream from one venous receptacle 
into the other half a dozen times, and closing the orifice of 
the receptacle to prevent drying, the blood was still more or 
less completely fluid after the lapse of eight or ten hours. 
On the other hand, if a fine sewing-needle is pushed through 
