62 SCIENCE PROGRESS 
3. The recognition by Fuld and Spiro and by Morawitz 
that the term “thrombin” is applied to bodies which possess 
quite different properties. 
Contrary to the results of previous observers in 1880, 
Edelberg,! a pupil of Schmidt, obtained intra-vascular clotting 
by the injection of solution of fibrin-ferment. In confirmation 
of the views of Schmidt that the fibrin-ferment was directly 
or indirectly a product of the leucocytes, Rauschenbach? in 
particular showed that not only leucocytes of the blood, but the 
cell-protoplasm of almost every tissue in the body, also yeast- 
cells (Wright), could markedly induce or accelerate coagulation 
in salted plasma, cooled plasma, and some, but not all, specimens 
of hydrocele and ascitic fluid. Tissues rich in nuclei possess 
this property not only zz vitro, but when injected into the 
circulation—a fact which was definitely established by Foa 
and Pellacani,*? who observed, moreover, that the tissue-extracts 
from the most varied sources, with the exception of the spleen, 
could induce intra-vascular clotting. Wooldridge? in particular 
confirmed these results, and in a remarkable paper showed 
that solutions of tissue-extract can not only cause a sudden 
death and produce extensive intra-vascular clotting, especially 
in the portal system, but that in dogs a definite dose per kilo 
body-weight can also produce conditions where the shed blood 
is found to be incoagulable. Further, a “ Schutzimpfung auf 
chemischem Wege” could be demonstrated. This, the earliest 
example of an acquired immunity conferred by injection, was 
proved by showing that a small dose of injected tissue-extract, 
which Wooldridge subsequently termed B-fibrinogen, rendered 
a dog immune to a subsequent lethal dose of the same sub- 
stance. These suggestive experiments, together with others 
on recognition of phosphorus in the extracts and his work 
on peptone-plasma led Wooldridge, like Rauschenbach, to 
speak of blood-plasma as protoplasma, and to hold that 
circulating blood contained within itself all that was essential 
for the coagulation process. The existence of fibrin-ferment 
played no part in his theory; both the coagulation and 
non-coagulation of blood was dependent upon the relations 
' Arch. f. exp. Path, u. Pharmak. ii. p. 283, 1880. 
* Inaugural Dissert, Dorpat, 1883. 
3 Bir. clin. di Bologna, p. 241, 1880. 
4 Du Bots Archiv, 1881. 
