310 THE BLOOD. 



in regard to his remarkable investigations or the foundations on which 

 he bases his theory and the objections which can be raised against it. 



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 arid 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 proven, 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- 

 tion of thrombin by the action upon the thrombokinase; the hirudin l 

 may, it is generally believed, as antithrombin make the thrombin inactive, 

 and the normal constituents of the plasma retarding coagulation perhaps 

 act in a similar manner. In other cases the retarding bodies act indirectly, 

 for they may, like the proteoses and others, cause the body to produce 

 special bodies which stand in close relation to intravascular coagulation. 



Intravascular Coagulation. It has been shown by ALEX. SCHMIDT and 

 his students, as also by WOOLDRIDGE, WRIGHT, 2 and others, that an 

 intravascular coagulation may be brought about by the intravenous 

 injection into the circulating blood of a large quantity of a thrombin 

 solution, as also by the injection of leucocytes or tissue fibrinogen (impure 

 nucleoprotein). Intravascular coagulation may also be brought about 

 under other conditions, such as after the injection of snake-poison (MARTIN 3 

 and others) or certain of the protein-like colloid substances, synthetically 

 prepared according to GRIMAUX'S method (HALLIBURTON and PICKER- 

 ING 4 ). If too little of the above-mentioned bodies be injected, then we 

 observe only a marked retarding tendency in the coagulation of the 



1 The action of hirudin is somewhat doubtful. See Schittenhelm and Bodong, 1. c. 



2 A Study of the Intravascular Coagulation, etc., Proceed, of the Roy. Irish Acad. 

 (3), 2. See also Wright, Lecture on Tissue or Cell Fibrinogen, The Lancet, 1892; 

 and Wooldridge's Method of Producing Immunity, etc., Brit. Med. Journ., Sept., 1891. 



3 Journ. of Physiol., 15. 



4 Ibid., 18. 



