174 THE BLOOD. 



intravascular injections of soap, peptone, and potassium oxalate on the 

 coagulation of blood is antagonised by previous intravascular injection of 

 the colloid. The action of the colloids in promoting coagulation is 

 assisted, like that of nucleo-proteid, by accumulation of C0 2 in the 

 blood. The same effects are produced by snake venom, 1 which contains 

 no nucleo-proteid, and the active principles of which consist of albumoses. 

 This produces, although in far more minute doses, effects which are in 

 every way comparable with those produced by Wboldridge's " tissue 

 fibrinogen." In doses of O00001 to O00002 grm. per kilog. body weight, 

 the venom of the Australian black snake (Pseudechis porphyriaca) causes 

 the blood, after a brief interval of increased coagulability (positive 

 phase), to lose its tendency to clot (negative phase), and much larger 

 doses of the poison will now not restore its coagulability. On the other 

 hand, moderate and large doses (more than O'OOOl grm. per kilog.) 

 produce instantaneous clotting within the vessels. But any blood 

 which has not undergone the intravascular coagulation is found to be 

 incoagulable in vitro, and in this point also there is an exact resemblance 

 to the phenomena produced by nucleo-proteids and by artificial colloids. 



Solutions of certain other chemical substances, such as ether, tannic 

 acid, arsenic, 2 glycerin, toluylenediamin, 3 are also found when injected 

 into the circulation to produce thrombosis. But, to produce the effect, 

 these all require doses large enough to cause disintegration of the 

 blood corpuscles, thereby setting free the nucleo-proteids which the 

 corpuscles contain, so that their action is probably a secondary one. It 

 is possible that snake venom may also operate in this way, 4 since it does 

 produce to a certain extent such disintegration, but the rapidity of the 

 production of the intravascular clotting, and the small amount of such 

 disintegration which normally occurs, render such an explanation 

 improbable. 



Peptone plasma. Researches of Wooldridge. Other substances, such 

 as commercial peptone, the action of which is due to the albumoses which 

 it contains, and leech extract, produce a diminution or loss of coagulability 

 when injected into the blood vessels, without, in any dose, tending to cause 

 intravascular coagulation. The incoagulable blood or plasma obtained 

 by their employment resembles very closely that obtained in the negative 

 phase, produced by Wooldridge's tissue fibrinogen, by colloids and by 

 snake venom. Peptone plasma can be made to coagulate by 



1. Addition of lymph cells. 



2. Addition of nucleo-proteids. 



3. Addition of calcium chloride. 



4. Dilution with water, or 0'5 per cent, salt solution. 



5. A stream of C0 2 . 



6. Neutralisation with acetic acid. 



But if an excess of the reagents employed to prevent coagulation 

 (or to produce the negative phase), whether peptones or slowly 



1 C. J. Martin, Journ. PhysioL, Cambridge and London, 1893, vol. xv. p. 380 ; and 

 Journ. and Proc. Hoy. Soc. New South Wales, Sydney, July 3, 1895. These papers contain 

 full references to the previous literature of the subject. 



2 The administration of arsenic and phosphorus by the mouth diminishes the coagulability 

 of the blood (of. Gley and Pachon, Arch, de physioL norm, et path., Paris, 1896, p. 716). 



3 Silbermann, Virchow's Archiv, 1889, Bd. cxvii. S. 288. 



4 C. J. Martin, op. cit., Journ. and Proc. Roy. Soc. New South Wales, Sydney, pp. 45-47 

 of reprint. 



