256 VENOMOUS SNAKES AND THE PHENOMENA OP THEIR VENOMS 



Following the above experiments Flexner and Noguchi proceeded to deter- 

 mine whether or not the reduction in toxicity of cobra venom through de- 

 terioration in fluid is accompanied by a reduction in its antivenin-combining 

 power. The sterile venom solution was kept for 19 days at room and ther- 

 mostat temperature, as in the foregoing experiments. They found that the 

 solution in the fresh state was able to kill a guinea-pig of about 300 gm. by 

 0.0001 gm. of venom. 0.0004 gm. of the venom became non-lethal when 

 injected into the guinea-pig after being mixed with 0.4 to 0.5 c.c. outside the 

 body. 



Table 34. — Crotalus-venom antivenin. 



itQ 



K = 0.048 



» 0.053 



«=! 



1.25 1.5 1.75 



o Guinea-Pig. 

 o Rabbit. 

 Fig. 10. 



The same venom solution, after standing at room temperature for 9 days, 

 became so weakened that 0.0004 E m - (instead of 0.0001 gm. of the original) 

 was required to kill a guinea-pig of the same weight. To neutralize 0.004 g m - 

 of this solution (weight being expressed in calculating back to the dried venom), 

 namely, 1 minimal lethal dose, 0.3 c.c. of the antivenin was necessary. 



The deterioration of toxicity was much greater at 37 C. kept 19 days and 

 it was found to require 0.00 1 gm. to kill the same test animal. Thus the 

 reduction was from 10 minimal lethal doses to 1 minimal lethal dose per mil- 

 ligram. For complete neutralization of 0.004 g m - = 4 minimal lethal doses 

 of this modified venom 0.8 c.c. of antivenin were necessary. 



The two experiments outlined above demonstrate that the deterioration of 

 cobra venom neurotoxin with age and higher (even at 20 C.) temperature is 



