58 PHYSIOLOGICAL CHEMISTRY. 



ferment, thoroughly beaten with a glass rod or whale-bone, and the 

 separated coagulum is washed first in water, and then with a 5$ 

 common-salt solution, and again with water, and lastly extracted 

 with alcohol and ether. 



A pure fibrinogen solution may be kept at the ordinary tempera- 

 ture until putrefaction begins without showing a trace of fibrin 

 coagulation. But if to this solution we add a water-washed fibrin 

 clot or a little blood-serum, it immediately coagulates and may 

 yield perfectly typical fibrin. The transformation of the fibro- 

 gen into fibrin requires the presence of another body contained 

 in the blood-clot and in the serum. This body, whose importance 

 in the coagulation of fibrin was first observed by BUCHANAN, was 

 later rediscovered by ALEXANDER SCHMIDT, and designated "fibrin 

 ferment." The nature of this enzymotic body has not been ascer- 

 tained. According to the investigations of GAMGEE, LEA, and 

 GREEN and HALLIBURTON, the " fibrin ferment " seems to be a 

 substance of the nature of the globulins. According to HALLI- 

 BURTON, it is a body derived from the lymphoid cells, a special 

 globulin, " cell-globulin" which differs from serum globulin partly by 

 fibrino-plastic properties and partly by having another temperature 

 of coagulation (-J- 60 C., or somewhat higher in a solution contain- 

 ing 10$ JSTaCl). The so-called fibrin ferment corresponds to the 

 enzymes in that only the very smallest amounts of it are required 

 for action, and further that on heating the solution it becomes in- 

 active. 



The isolation of the fibrin ferment has been tried in several 

 ways. Ordinarily it may be prepared by the following method 

 proposed by ALEX. SCHMIDT : Precipitate the serum or defibrinated 

 blood with 15-20 vols. of alcohol and allow it to stand a few months. 

 The precipitate is then filtered and dried over sulphuric acid. The 

 ferment may be extracted from the dried powder by means of 

 water. 



If a fibrinogen solution containing salt, as above described, is 

 treated with a solution of " fibrin ferment," it coagulates at the 

 ordinary temperature more or less quickly and yields a typical 

 fibrin. Besides the fibrin ferment the presence of neutral salts is 

 necessary, for without them ALEX. SCHMIDT has shown the coagu- 

 lation of fibrin does not take place. The amount of fibrin obtained 



