160 ANIMAL PHYSIOLOGY. 
3. Paraglobulin may be obtained from serum also, and fibrin- 
ogen from certain fluids occurring normally (pericardial, pleu- 
ral, etc.) or abnormally (hydrocele fluid). 
4, Serum added to these fluids sometimes induces coagula- 
tion. 
5. Coagulation may occur spontaneously in the above-men- 
tioned fluids when removed from the natural seat of their for- 
mation. ° 
6. A preparation, made by extracting serum or the whipped 
(defibrinated) blood added to specimens of certain fluids when 
they do not coagulate spontaneously, as hydrocele fluid, often 
induces speedy clotting. : 
7. This extract (fibrin-ferment) loses its properties on boil- 
ing, and a very small quantity suffices in most cases to induce 
the result. For these and other reasons this agent has been 
classed among bodies known as unorganized fermenis, which 
are distinguished by the following properties: 
They exert their influence only under well-defined circum- 
stances, among which is a certain narrow range of tempera- 
ture, about blood-heat, being most favorable for their action. 
They do not seem to enter themselves into the resulting prod- 
uct, but act from without as it were (catalytic action), hence a 
very small quantity suffices to effect the result. In all cases 
they are destroyed by boiling, though they bear exposure for 
a limited period to a freezing temperature. 
The conclusions drawn from the above statements are these: 
1. Coagulation results from the action of a fibrin-ferment on 
fibrinogen and paraglobulin. 2. Coagulation results from the 
action of a fibrin-ferment on fibrinogen alone. 3. Denis plasmine 
is made up of fibrinogen and paraglobulin. 
From observations, microscopic and other, it has been con- 
cluded that the corpuscles play an important part in coagula- 
tion by furnishing the fibrin-ferment; but the greatest diver- 
sity of opinion prevails as to which one of the morphological 
elements of the blood furnishes the ferment, for each one of 
them has been advocated as the exclusive source of this fer- 
ment by different observers. 
The above conclusions do not seem to us to follow neces- 
sarily from the premises. It might be true that a solution of 
fibrinogen, on having fibrin-ferment added to it, would clot, and 
yet it would not follow that such was the process of coagula- 
tion in the blood itself. All specimens of hydrocele fluid, and 
similar ones not spontaneously coagulable, do not clot when 
\ 
