456 
COAGULATION OF THE BLOOD. 
appears to me that the medical profession is deeply indebted 
to Dr. Richardson for his laborious and able investigations, 
which have, as I think, removed much mystery from this 
long-vexed question. 
u But Dr. Richardson aims at much more than the ex- 
planation of coagulation outside the body. He believes that 
the fluidity of the blood within the healthy living vessels is 
due simply and solely to the presence of free ammonia, which 
he supposes to be generated either in the systemic or pul- 
monary capillaries, and he denies that the walls of the arteries 
or veins have any effect on the blood by virtue of their 
vitality, or exercise any other influence upon it than that of 
checking the evolution of ammonia, just as would be the case 
were they tubes of dead matter of the same degree of per- 
meability. And all cases of coagulation within the living 
body are supposed, by him, to be explicable on simple che- 
mical principles. Here, however, I find myself quite unable 
to follow him. Thus, he believes that the coagulation in an 
aneurism is the result of the blood which is at rest in the 
tumour giving up its ammonia to the current which is flowing 
past the mouth of the sac. This theory was suggested to 
him by the following circumstance : In one of the experi- 
ments of transmitting air through successive portions of 
blood, the longer tube in the last Wolfe’s botLle was acci- 
dentally too short, so that it did not reach further than about 
an inch from the bottom of the vessel. The result was, that 
while the upper part of the blood in this last bottle was 
retained fluid for a considerable time, that below the level to 
which the tube reached speedily coagulated. Dr. Richardson 
infers that the lower portion of blood gave up its ammonia to 
the air which was bubbling through the upper part sufficiently 
charged with the alkali to retain that part in a state of fluidity. 
But, surely, this implies a mistake in chemistry. The loner 
portion of blood coagulated, I imagine, for the same reasons 
that it would have done had it been put in a stoppered bottie* 
after passing through the air, though probably not quite so 
rapidly, while the other part was prevented from coagulating 
by the ammoniacal vapour bubbling through it. 
head and proceeding backwards, so as to avoid all tension upon the en- 
closed blood, which was, of course, displaced freely in the direction towards 
the thorax. By this means a number of portions of blood were obtained 
enclosed in receptacles nearly, though not absolutely, impermeable to gases. 
The various compartments were opened at different intervals, and up to 
three hours some of them contained fluid blood which coagulated on expo- 
sure, whereas there was in others a considerable portion of coagulum. 
After four hours, coagulation was almost complete, but a slender thread of 
fibrine was still obtained from the fluid part in one of t he divisions a few 
minutes after it had been let out. 
* This occurrence I have frequently observed. — J. L. 
