166 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



These two investigators made the experiments: (i) With a fixed volume of 

 blood mixed with a fixed volume of cobra poison of known strength in a 

 haemocytometer pipette, and the corpuscles in a given field counted from time 

 to time. (2) Mixing known volumes of blood and poison solutions in small 

 test-tubes and observing in which series of tubes haemoglobin was dissolved. 



Care was taken to have solutions isotonic or slightly hypertonic. It was 

 found that cobra venom has marked haemolytic powers upon bloods of various 

 kinds of animals as well as man, and that these powers could be checked in 

 the test-tube by the addition of the antivenomous serum. Antivenomous 

 serum, alone, has the power to inhibit the haemolysis. All other sera tried 

 were without effect. They also found that relationship held good for mul- 

 tiples of these numbers. The proportions varied with different bloods. 



In endeavoring to determine whether there might be some relationship 

 between the neutral point in vitro and the protective power of the antivenin 

 in cor pore, they found that, for a guinea-pig weighing 250 to 300 gm., o.oooi 

 gm. of cobra venom was the minimal lethal dose, death ensuing in 5 to 8 

 hours. The haemolytic action of this poison was neutralized by o.i c.c. of 

 isotonic antivenin, and such a mixture they found was never fatal to animals, 

 but if the haemolytic action was completely neutralized the guinea-pig might 

 or might not die. When, however, larger quantities of the venom, completely 

 neutralized as regards haemolysis, were used, they were found to be rapidly 

 fatal on injection, 5 out of 6 animals dying. Thus the investigators conclude 

 that there is no positive connection between the neutralization and the haemo- 

 lytic and toxic actions of the venom. Their results are summarized thus: 



(1) Cobra poison is strongly haemolytic in vitro. 



(2) This action is neutralized by antivenomous serum, and the action of 

 the latter is specific. 



(3) For certain doses (o.oooi gm.) the measure of this neutralization in 

 vitro is a neutralization in corpore for guinea-pigs. 



(4) This neutralization is chemical, not cellular or vital. 



In a subsequent communication 1 on the same subject, Myers and Stephens 

 state that poison solutions containing from 0.002 to 0.0075 8 m - m T c - c - 

 haemolyze blood not at all; at other times, less completely than weaker solutions 

 do. Dog's blood is found to be exceedingly sensitive to the poison, haemolysis 

 in this animal occurring in very dilute solution for instance, in the strength of 

 0.5 c.c. = 0.000009 gm. Further, with regard to dog's blood (and the same 

 holds good for frog) it was observed that the haemolysis was often complete in 

 less than an hour in solutions of various strengths, while in the corresponding 

 tubes for guinea-pig and man haemolysis was not apparent for three to four 

 hours, though eventually complete. 



In continuation of the investigations which he commenced with Myers, 

 Stephens 2 made another valuable contribution to our knowledge as to the 



1 Stephens and Myers. The action of cobra poison on the blood. A contribution to the study of 

 passive immunity. Tour, of Pathol. and Bacteriol., 1898, V, 279. 



3 Stephens. On the haemolytic action of snake toxins and toxic sera. Jour, of Pathology and Bac- 

 teriology, 1900, VI, 273. 



