686 
COAGULATION OF TIIK BLOOD. 
remained in the basin coagulated in a few minutes. He also 
found that blood continued in the heart of a turtle long after 
the injection of air into the heart through a vein, till the 
cavities of the organ contained a foamy mixture of blood 
and air. 
Yet it by no means follows that the vital theory and the 
ammonia theory are necessarily altogether inconsistent.. It 
might be true, for anything we could tell, a priori, that the 
coagulation of the blood, when shed from the body, might 
depend on the evolution of a certain amount of ammonia, 
previously holding the fibrin in solution, and yet it might, at 
the same time, be true that the cause of the ammonia remain¬ 
ing in the blood in the healthy vessels might be an action of 
the living vessels retaining it there. It might be that an 
action of the living vessels might chain down the ammonia 
and prevent it from escaping, whereas, when shed from the 
body, it would be free to escape. 
This notion was, I confess, at one time entertained by 
mys'elf; and one of my earliest experiments was performed 
with a view to the corroboration of the ammonia theory as 
applied to blood outside the body. It seemed to me desirable 
that further evidence should be afforded of the effect of mere 
occlusion from air in maintaining the blood fluid. If the 
ammonia theory were true, then if blood could be shed 
directly from a living vessel into an air-tight receptacle 
composed of ordinary matter it ought to remain fluid. For 
this purpose I made the following experiment:—I tied into 
the jugular vein of a sheep a long vulcanised india-rubber 
tube, adapted by means of short pieces of glass tube at its 
extremities, both ends being connected with the vessel, so 
that the current of blood might be permitted to flow through 
the tube, and then continue its natural course. When it had 
been ascertained that the blood was circulating freely through 
the tube—which could be readily done by placing the finger 
on the cardiac aspect of the vein, which was then made to 
swell if the circulation was proceeding through the tube— 
pieces of string, well waxed, were tied at intervals of about 
two inches round the tube, which was thus converted into a 
number of air-tight receptacles containing blood, which cer¬ 
tainly had no opportunity for the escape of ammonia. The 
tube was then removed, and I found, in accordance with the 
view that I was disposed to entertain, that the blood, instead 
of coagulating completely in a few minutes, as it would liave 
done if slied into a cup, remained partially fluid in these 
receptacles after the lapse of three hours. But I have since 
fcHUul that, if the experiment be repeated in the same way as 
