322 THE BLOOD. 



is formed. Thrombin is a fibrin incompletely saturated with fibrinogen, 

 and in the coagulation of fibrinogen with thrombin the still unsatisfied 

 affinities of the latter are saturated. ("La thrombine d'A. Schmidt n'est- 

 pas autre chose que de la fibrine insuffisamment pourvue de fibrinogene. 

 Dans la coagulation du fibrinogene par la thrombine les affinites restees 

 libres de celle-ci peuvent s'assouvir; le compose moins sature se trans- 

 forme en un compose plus sature.") The formation of fibrin from 

 fibrinogen is not, according to NOLF, an enzymotic process, and ,the 

 thrombin is only a residue of the fibrin remaining in solution. 



In NOLF'S opinion the thrombogen is probably formed in the liver 

 and found to a large extent in all plasma. The thrombozym is secreted 

 by the leucocytes and the endothelial cells, and in opposition to MORA- 

 WITZ is not secreted by other cells. It is also a normal constituent of the 

 blood-plasma circulating in the living body. Most tissues, on the con- 

 trary, contain no thrombozym. The tissue extracts, NOLF believes, 

 also contain no substances absolutely necessary for the coagulation, 

 but only bodies which can have a powerful accelerating action, the 

 thromboplastic substances which are mixed with the thrombokinase of 

 MORAWITZ. The circulating blood-plasma contains all the bodies directly 

 necessary in the coagulation, namely, fibrinogen, thrombogen, throm- 

 bozym and lime salts. Besides these it also contains a substance that 

 inhibits coagulation, antithrombin, which is formed in the liver. There 

 exists, if the author understands the work of NOLF, a labile equilibrium 

 between the various constituents of the plasma, and this equilibrium is 

 destroyed in coagulation. The first impulse to coagulation is given by 

 the thromboplastic substances. 



NOLF considers as thromboplastic active any influence of a physical 

 or chemical nature which, be it produced by the walls of the vessel, a 

 suspended body, a solvent or a dissolved body, a colloid or crystalloid, 

 a molecule or an ion, makes the combination of the three above colloids 

 possible. To the thromboplastic agents belong the walls of a glass 

 vessel, finely powdered glass, the precipitates of calcium oxalate or 

 calcium fluoride, also living protoplasm, aqueous tissue extracts, the 

 alcohol soluble zymoplastic substances of ALEX. SCHMIDT, and other 

 substances. All these agents in some way or other may serve as points 

 of precipitation. That a plasma free from form-elements coagulates 

 for example on contact with the walls of a glass vessel depends upon the 

 fact that the inhibitory action of the antithrombin is retarded by the 

 thromboplastic action of the foreign surface. Unfortunately we are 

 not certain as to how this thromboplastic action is brought about. 



An important side of NOLF'S theory of coagulation is also the fibrinol- 

 ysis which is brought about by the thrombin. The proteolytic action 

 of the thrombin is due only to the thrombozym contained therein, and 



