COAGULATION OF THE BLOOD. 323 



it has a proteolytic action only upon fibrin and not upon fibrinogen. 

 According to NOLF, coagulation is merely a preparation for the prote- 

 olysis, and is a nutrition phenomenon, and in addition is of special 

 importance, in arresting hemorrhage'. In order to prevent a rapid 

 fibrinolysis, the plasma also contains one or more antifibrinolytic sub- 

 stances, which are secreted by the liver. 



What has been given contains the chief points in NOLF'S theory 

 of coagulation, and it is impossible in a text-book to enter more into 

 detail in regard to his remarkable investigations or the foundations 

 on which he bases his theory and the objections which can be raised 

 against it. 



Recently other investigators as RETTGER and HOWELL have raised 

 objections to the view that the coagulation of the blood is an enzymotic 

 process. STROMBERG l also leans toward such a conception and they 

 all raise the objection that the quantity of fibrin increases with the quan- 

 tity of thrombin. This behavior, which has been known for a long time, 

 is of such a complicated nature, that no positive conclusions can be drawn 

 therefrom. 



The belief of MELLANBY 2 that the plasma originally only contains one 

 globulin, fibrinogen, from which by enzymotic cleavage the fibrin and serglobulin 

 are formed, is untenable and is based upon the imperfect methods of preparing 

 fibrinogen that he used. 



From the above description of the various theories of coagulation 

 it at least follows that in the study of the coagulation of the blood there 

 are many contradictory statements and observations, and so many obscure 

 points, that for the present it is impossible to give a clear, comprehensive 

 summary of the different views and to deduce a theory of the process 

 of coagulation which would embrace all the factors. In spite of this 

 confusion and all contradictions, still we are sure that certain bodies such 

 as fibrinogen and thrombin, even though this latter be an enzyme or a 

 colloid combination, are directly concerned in the formation of fibrin, 

 while other bodies act indirectly as accelerators or inhibitors of coagulation. 



The bodies accelerating coagulation, with the exception of gelatin, 

 whose action in this regard has not been positively proved, have been 

 mentioned several times above. The mode of action of the bodies retard- 

 ing coagulation is not clear and is much disputed. Their action may, 

 it seems, also be more of a direct or indirect kind. Thus, for example, 

 the oxalate and fluoride may prevent the formation of thrombin by 

 precipitation of the lime. The cobra-poison seems to prevent the forma- 



1 Rettger, Amer. Journ. of Physiol., 24; Howell, ibid., 26; Stromberg, Bioch. 

 Zeitschr., 37. 



2 Journ. of Physiol., 38. 



