COAGULATION OF THE BLOOD. 
755 
glass tube being also connected by india-rubber, with a 
wooden handle, which handle was provided with an upright 
piece of wire, from which spokes projected in different direc¬ 
tions, so that they would, wdien moved, act as a churn on 
any blood contained in the lower portion of tube. When 
the lower piece of tube was fixed by means of a vice, the 
flexibility of the india-rubber permitted the churn to be 
rotated so as to expose the blood to its influence. This 
having been arranged, I first poured in strong liquor am- 
moniae, so as to get rid of any slight acidity which the con¬ 
stituents of the apparatus might be conceived to possess; 
and then, having poured out the ammonia, filled up the 
apparatus with water, and boiled the whole in a large 
glass test-tube till all bubbles of air in any portion of 
it were expelled. Having then tied into a branch of the 
carotid artery of a calf a bent tube of small diameter, 
and having permitted the blood to flow till it escaped at the 
orifice of the tube, I compressed the artery and passed the 
tube down through the water to the bottom of the apparatus, 
and then let the blood flow again, which had the eJffect of 
displacing all the water; and when the blood appeared at 
the top of the apparatus the tube was withdrawm, when two 
effectual clamps were placed on the vulcanized india-rubber; 
the india-rubber was then divided between the clamps. 
The upper portion of the apparatus, the orifice of which 
was exposed to the air, was set aside and left undisturbed. 
Having ascertained that the lower portion had been effectually 
sealed by the clamp, and thus prevented from any oppor¬ 
tunity of escape of ammonia, I subjected it to the action of 
the churn for a certain number of minutes. It so happened 
that the blood of that calf w'as very slow in coagulating. I 
knew this from previous experiments on the animal, and 
therefore continued the action of the churn for a considerable 
time—namely, thirty-seven minutes. I then found the wire 
enveloped in a mass of clot; and examination of the fluid 
residue with a needle indicated that the fibrin had been all 
withdrawn from the blood on which the churn had acted. 
I did not now examine the other portion of the apparatus 
which had been set aside; but at the end of an hour and a 
quarter, when more than double the time had elapsed, I 
investigated this, and found the blood in it for the most 
part still fluid and coagulable. Thus the blood in the 
churn, which from the time it left the artery had no oppor¬ 
tunity of parting with its ammonia, coagulated much more 
rapidly than that in an open vessel. The difference between 
the two w\as that the lower portion of the blood had been 
freely exposed to the influence of the foreign solid, whereas 
