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 CO a 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 iu far more minute doses, effects which are in 
every way comparable with those produced by Wooldridge's " tissue 
fibrinogen." In doses of O'OOOOl to 0'00002 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 0*0001 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. 3S0 ; and 
Journ. and Proc. Boy. 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 (cf. Gley and Pachon, Arch, dephysiol. 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. 
