324 THE BLOOD. 



tion of thrombin by the action upon the thrombokinase; the hirudin 1 

 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 PICKERING 4 ). If too little of the above-mentioned bodies be injected, 

 then we observe only a marked retarding tendency in the coagulation 

 of the blood. According to WOOLDRIDGE it can generally be maintained 

 that after a short stage of accelerated coagulability, which may lead to a 

 total or partial intravascular coagulation, a second stage of a diminished 

 or even arrested coagulability of the blood follows. The first stage is 

 designated (WOOLDRIDGE) as the positive and the other as the negative 

 phase of coagulation. These statements have been confirmed by several 

 investigators. 



There is no doubt that the positive phase is brought about by an 

 abundant introduction of thrombin, or by a rapid and abundant for- 

 mation of the same. The explanation of the production of the negative 

 phase, which can easily be brought about by pepsin proteoses, by various 

 bodies such as extracts of crabs' muscles and other organs, eel-serum, 

 enzymes, bacterial toxines, certain snake-poisons, etc., has been attempted 

 in different ways. The best studied is the action of proteoses, but no 

 conclusive results have been obtained thus far. The assertion of PICK 

 and SPIRO that the action of the proteoses does not depend upon the 

 proteoses themselves, but upon a contaminating substance, the protozym, 

 is claimed to be incorrect by UNDERBILL, while the recent investigations 

 of POPIELSKI indicate that this is correct. The bodies retarding coagu- 



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. 



