114 ON THE COAGUTALION OF THE BLOOD 
in the lower portion of tube. When the lower piece of tube was fixed by mean of 
a vice, V, 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 ammoniae, 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, C, of a calf a bent tube of 
small diameter, as represented, 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 effect of displacing all the water; and when the 
blood appeared at the top of the apparatus, the tube was withdrawn, when two 
effectual clamps, Cl, Cl, were placed on the vulcanized india-rubber connecting 
A and B; the india-rubber was then divided between the clamps, and we had 
the state of things represented at the right-hand side of the diagram. 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 was 
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, viz. 
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 fibrine 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been all withdrawn from the blood on which the churn had acted.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 opportunity of parting with its ammonia, coagulated 
much more rapidly than that in an open vessel. The difference between the two 
was that the lower portion of the blood had been freely exposed to the influence 
of the foreign solid, whereas the other had only been subjected to the action 
of the wall of the tube. 
The same principle may be illustrated by an exceedingly simple experiment 
which I performed only this very day. Receiving blood from the throat of a 
bullock into two similar wide-mouthed bottles, I immediately stirred one of them 
with a clean ivory rod for ten seconds very gently, so as to avoid the intro- 
