VENOM ILEMOLYSIS AND VENOM AGGLUTINATION 167 



biological nature of haemolytic and toxic constituents of snake venoms and 

 certain toxic serums. In this article Stephens confirmed the peculiar anti- 

 hsemolytic property of cobra venom when employed in a strong concentra- 

 tion, namely, more than o.ooooi gm. in i c.c. He failed to find the reason 

 for this non-occurrence of haemolytic phenomenon in a concentrated venom 

 solution, but at the same time he brought out another puzzling phenomenon 

 with cobra haemolysis that the addition of a large quantity of horse serum 

 to such mixture (large quantity of the venom and the blood) induces a rapid 

 and complete haemolysis. At that time this was entirely inexplicable, although 

 we to-day understand it and I will later return to this phenomenon. 



In testing the neutralizing power of Calmette's antivenin against the haemo- 

 lytic principles contained in various snake venoms, Stephens found that it had a 

 very slight neutralizing action on the haemolysins of the venoms of Daboia, 

 Crotalus terrificus, and Pseudechis porphyriacus. Against cobra venom the 

 antivenin neutralized the lytic action of 0.00045 8 m -> or about 4 minimal 

 lethal doses, while the same quantity could neutralize only 0.00003 gm. of 

 daboia venom, a quantity far less than the lethal dose. Stephens states that 

 normal or antivenomous serums of horse sometimes produce quite marked 

 and progressive haemolysis and sometimes an opposite effect. Thus, when 

 antivenin was introduced in a dose insufficient to neutralize cobra venom 

 completely, a much prompter haemolysis may occur than in the saline venom 

 solution. Here he expresses his uncertainty as to the identity of the haemo- 

 lytic principles existing in different venoms. 



Stephens's observations on the haemolytic and toxic effects of the serums 

 of Tropidonotus natrix, python, frog, and eel, as compared with those of 

 venoms, are very interesting. With the tropidonotus serum he found a cer- 

 tain antihaemolytic action of antivenin, while normal horse serum had none. 

 He found that a rabbit immunized against the tropidonotus serum to quite a 

 high degree succumbed quickly to a single lethal dose of the serum of an 

 Australian python, and concluded that the haemolytic as well as toxic constitu- 

 ents of these two serums can not be identical. While the serum of horse had 

 marked promoting effect upon the cobra as well as daboia venom haemolysis, 

 an inhibitory effect was found in the serums of the snake. 



Stephens filtered a 0.25 per cent solution of cobra venom through a 

 gelatinized bougie, which had previously been used to filter bullock serum, 

 until the filtrate gave no albumin reaction. By repeated filtrations under high 

 pressure, the filtrate was tested each time for its haemolytic and toxic actions. 

 The filtrate was still active after the third passage, but no more after the 

 fourth. A trace of biuret reaction was given with this last filtrate. 



In 1900 Walter Myers contributed another very exhaustive study on the 

 nature of toxic constituents of cobra venom. From his own experiments, as 

 well as from those of many of his predecessors, notably those of Weir Mitchell 

 and Reichert, he concluded a priori that in the venom of cobra di capcllo 

 there are present at least two poisonous substances. One of these is haem- 

 olytic, and the other causes death, probably by its action on the respiratory 



