Coagulant of the Venom of Echis carinatus. 187 



blood was diminished. It may here he observed that very small doses 

 (0 03 mgrm. or less per kilogramme of body weight) fail to produce any 

 recognisable ill effect in rabbits. 



The effect of intravenous injection of viper venom upon circulating blood 

 plasma was studied in a series of experiments similar to the following : — 



Experiment 4. — A rabbit weighing 384 grm. received into the vein of the 

 ear an injection of 2 c.c. of - 65-per-cent. sodium chloride solution containiug 

 - 13 mgrm. of viper venom (0 34 mgrm. per kilogramme of body weight). 

 Five minutes after the completion of injection, which occupied one minute, 

 the animal, which had not up to this time been obviously affected, showed 

 signs of feebleness, and then became convulsed, death occurring about three- 

 quarters of a minute later. At the post-mortem examination, which was 

 made without delay, the blood in the superior vena cava, the right auricle 

 and ventricle of the heart and the pulmonary artery was found to be 

 clotted, the clot extending into the vein injected ; on the left side of the 

 heart, in the aorta, portal vein, and lower part of the vena cava, liquid 

 blood was found ; the lungs collapsed normally on opening the chest. 



On microscopical examination of the lungs after death by viper venom it 

 was found that in all cases, no matter whether intravascular coagulation 

 resulted (four experiments) or the blood coagulated slowly (three experi- 

 ments) or remained permanently liquid (three experiments), fibrin masses, 

 filaments, and fibrils could be readily recognised. The appearance presented 

 by the collections of fibrin was exactly the same as that presented when 

 relatively large doses of thrombin solution had been injected, so that it was 

 not possible from an examination of the lungs to state whether the coagulant 

 injected had been the latter or the former. The diminished coagulability or 

 " negative phase " exhibited after the intravenous injection of viper venom 

 is therefore dependent upon the removal of fibrinogen under the action of 

 the coagulant. As already mentioned, Martin* observed that the slow 

 injection in the dog of small quantities (i.e. below 0*1 mgrm. per kilo- 

 gramme of body weight) of viper (Pseudechis porphyriacus) venom resulted 

 in the production of liquid blood, and it is easy to understand how this 

 procedure, by allowing time for the contraction of the delicate fibrin 

 network, which is at first formed, into dense masses of relatively small size, 

 would cause far less blocking of vessels and resulting interference with the 

 circulation than would the rapid injection of the same or smaller amounts 

 of venom. Nevertheless, in my experiments upon rabbits, liquid blood has 

 followed the injection (in the course of about one minute) of relatively large 



* C. J. Martin, 1893, he. cit., p. 382. 



