THE BLOOD. 161 
fibrin-ferment is added. Moreover, fibrin-ferment has not been 
isolated as an absolutely distinct chemical individual, free from 
all impurities. 
Because fibrinogen and paraglobulin give rise, under certain 
circumstances (it is asserted), to fibrin, and since plasmine acts 
likewise, it does not follow that plasmine contains these bodies. 
Further, it is stated that in the blood of crustaceans the clot 
arises from the corpuscles chiefly, which run together and 
blend into a homogeneous mass. The fibrin so called in such 
acase differs not a little chemically, it could probably be shown, 
if our tests were delicate enough to discover it, from that which 
is denominated fibrin in other cases. “ Fibrin-ferment” seems 
to have been used to cover much ignorance and unnecessary 
invention, as we shall endeavor to show later on; and we can 
not but regard the reasoning in regard to the coagulation of 
the blood as evidence of an erroneous interpretation of certain 
facts on the one hand, and a large oversight of additional facts 
on the other hand. 
In the mean time we turn to certain well-known phenomena 
which bear a clear interpretation: 1. The blood remains fluid 
in the vessels for some time after the death of an animal; clots 
first in the larger vessels, and keeps fluid longest in the smaller 
veins. 2. The blood in the heart of a cold-blooded animal, as 
that of the frog or turtle, which will beat for days after the 
animal itself is dead, maintains its fluidity, but clots at once on 
removal. 3. The blood inclosed in a large vein removed be- 
tween ligatures does not coagulate for many hours (twenty- 
four to forty-eight). 
There are also facts of an opposite nature, thus: 1. When 
blood passes from a blood-vessel into one of the cavities of the 
body, it clots as if shed externally. 2. If a ligature be passed 
tightly around an artery so as to rupture the elastic coat, co- 
agulation ensues at the site of the ligature. 3. A similar 
clotting results when the inner coat of a blood-vessel is dis- 
eased, as in the case of roughening of the valves of the heart 
from inflammation, or the changes that give rise to aneurism 
of an artery. 4. A wire, thread, or other like foreign body, 
introduced into a vein, is speedily covered with fibrin. 
These facts, and others of like character, have been inter- 
preted as indicating that the living tissues of the blood-vessel or 
heart in some way prevent coagulation, but as to details there 
is difference of opinion. Some believe that the fibrin-ferment 
(essential to coagulation, according to their view) is formed by 
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