COAGULATION OF THE BLOOD. 
435 
it had run down the side of the glass, and, as a consequence 
of this almost momentary contact with the foreign solid, the 
central parts, like the circumferential, underwent the process 
of coagulation. 
Mysterious as this subtle agency of ordinary solids must 
appear, its occurrence is thus matter of experimental demon¬ 
stration, and by it the coagulation of blood shed in a basin 
is accounted for; while it is also exclusively shown from this 
experiment that the blood, as it exists within the vessels, has 
no spontaneous tendency to coagulate, and therefore that the 
notion of any action on the part of the blood-vessels to pre¬ 
vent coagulation is entirely out of the question. The 
peculiarity of the living vessels consists not in any such 
action upon the blood, but in the circumstance (remarkable, 
indeed, as it is) that their lining membrane, when in a state 
of health, is entirely negative in its relation to coagulation, 
and fails to cause that molecular disturbance, or, if we may 
so speak, catalytic action, which is produced upon the blood 
by all ordinary matter. 
I afterwards found that the simplest method of maintain¬ 
ing blood fluid in a vessel composed entirely of ordinary 
matter was to employ a glass tube similar to those above 
described, except that its upper end was closed by a cork 
perforated by a narrow tube terminating in a piece of 
vulcanized india-rubber tubing that could be closed by a 
clamp. This tube was slipped down into a vein till the blood, 
having filled it completely, showed itself at the orifice of the 
india-rubber tubing, to which the clamp was then applied. 
The whole apparatus was now quickly inverted, and the vein 
was drawn off from over the mouth of the tube, which was 
then covered with gutta-percha tissue to prevent evaporation. 
After the inverted tube had been kept undisturbed in the 
vertical position for nineteen hours and three quarters, 
coagulable blood was obtained from the interior of the clot. 
We have seen that a clot has but very slight tendency to 
induce coagulation in its vicinity unless the blood has been 
acted on by an ordinary solid; and it is probable that with 
perfectly healthy blood it would be unable to produce such 
an effect at all. This appears to me to be very interesting 
physiologically, but especially so with reference to pathology. 
I must not now go fully into the circumstances that led me 
to it, but I may express the opinion I have formed—that 
clot must be regarded as living tissuein its relation to the blood. 
It is, no doubt, a very peculiar form of tissue in this respect, 
that it is soft, easily lacerable, and easily impaired in its vital 
properties. If disturbed, as in an aneurism, it will readily be 
