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Dr. J. O. W. Barratt. The Nature of the 



quantities of venom (3 - 4-0 - 6 ingrm. per kilogramme of body weight). 

 Liquid blood, moreover, does not exclude the presence of visible clot in the 

 larger vessels. Thus in the experiment referred to at the close of the next 

 section, in which - 73 mgrm. of venom per kilogramme of body weight was 

 injected into a rabbit, it was found that the heart was continuing to beat 

 feebly and slowly after respiration had stopped and all movements of the 

 voluntary muscles had ceased. On opening the right ventricle 5 c.c. of 

 blood was obtained, which remained permanently liquid. The vein of the 

 ear, external jugular, superior and inferior caval veins, portal and renal 

 veins were all distended with clot ; nevertheless, obstruction to the circula- 

 tion was not complete, and blood was delivered from the incised right 

 ventricle at each beat. In the blood-vessels of the lungs fibrin filaments and 

 masses were abundant. 



That the appearance of liquid blood after injection of viper venom is 

 dependent upon removal of fibrinogen is shown not only by the appearance 

 of fibrin in blood-vessels, particularly of the lungs, but also by the result 

 of examination of the fibrinogen content of the liquid blood. Thus it was 

 found that when one part of the thrombin solution employed in the pre- 

 ceding section was mixed with two parts of the liquid blood obtained in the 

 experiment just described, coagulation did not occur, though the thrombin 

 solution was capable of coagulating two parts of fibrinogen solution in about 

 three-quarters of a minute. The liquid blood was, however, found to 

 contain thrombin, for when added to two parts of fibrinogen solution 

 coagulation occurred at the end of one and a half minutes ; the same result 

 was obtained if one-fifteenth part of - 83-per-cent. potassium oxalate 

 solution had also been previously added. The thrombin in question cannot 

 have been produced by the action of venom upon fibrinogen, for serum 

 expressed from a coagulum so obtained, as, for example, in the second 

 experiment of the series given on p. 189, exhibits the usual character of serum 

 from a clot produced by the action of thrombin upon fibrinogen solution 

 under similar conditions of experiment, that is to say, it possesses scarcely 

 any recognisable coagulant action on fibrinogen. It follows, therefore, that 

 the thrombin contained in the liquid blood consists of venom. In the 

 experiment in question the amount of venom injected into the blood 

 represented 1 part in 70,000 parts of blood. In the next section it is shown 

 that 1 part in 15,000,000 is capable of coagulating a solution containing 

 fibrinogen in approximately two-fifths of the concentration present in blood 

 plasma ; it is therefore to be expected that part of the venom injected would 

 remain unchanged in the liquid blood, thereby conferring upon it a coagulant 

 action when added to fibrinogen solution. 



