THE MODE OF ACTION OF COBRA VENOM. 293 



From this, two groups of blood-cells can at once be recognized 7 

 namely, blood-cells like those of guinea-pig, dog, rabbit, man, and 

 horse, which are dissolved by the cobra venom, and blood-cells which 

 are not affected under these circumstances even with large amounts 

 of the poison. The sensitive blood-cells do not all possess the same 

 vulnerability, but manifest considerable variations, depending on 

 the species to which they belong. This is the case with all haemolytic 

 poisons. Naturally besides this there are certain individual fluctua- 

 tions in vulnerablilty. The blood-cells of the dog and the guinea- 

 pig are the most sensitive since as a rule 0.25 cc. of a 1: 10,000 dilu- 

 tion of the poison still produces complete solution. The blood-cells 

 of the horse proved least sensitive, for here it required 1.0 cc. of a 

 1:1000 dilution of the poison to produce solution. The difference 

 in vulnerability is therefore one of forty times. 



In view of Flexner and Noguchi's experiments by which the 

 amboceptor character of the haemolytic portion of snake venoms 

 was demonstrated, it seemed advisable to undertake activating 

 experiments in those cases in which the cobra venom did not effect 

 spontaneous solution. 



It was actually very easy to produce solution by the addition of 

 foreign sera. We shall shortly show that when the observations of 

 Calmette 1 are taken into account these activities are not all due to 

 complements. According to our conception only such substances are 

 complements which in general are inactivated at a temperature 

 between 52 and 60, in some cases even somewhat higher. This 

 corresponds to the greater or less degree of lability of the complements 

 thus far known. 



. In our experiments such pure complementings were met with 

 in the following combinations: 



Horse blood ox serum 



Ox blood guinea-pig serum 



Sheep blood guinea-pig serum 



Rabbit blood guinea-pig serum 



Table II shows such an activation of the cobra venom. It also 

 shows that the serum employed lost its complementing property 

 by half an hour's heating to 56. 



1 A. Calmette, Sur 1'action hemolytique du venin de cobra. Comptes rend, 

 de I'Acade'mie des Sciences, T. 134, No. 24, 1902. 



