256 VENOMOUS SNAKES AND THE PHENOMENA OF 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 
©.c00r 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. 
Rabbits, 
Guinea-pigs. intravenously. 
q calc. II. q obs. 
2 
9 
7 
4. 
Si 
2. 
I. 
i 
I 
oO. 
O08 HEN s Be oviosid 
AHPOMNUNTA~ © 



p=1 K=0.048 K=0.053 n=35 
° 0.25 O8 9.75 in 1.25 1.5 1.75 Zh 2.25 25 
o Guinea-Pig. 
o Rabbit. 
FIG. ro. 
The same venom solution, after standing at room temperature for 9 days, 
became so weakened that 0.0004 gm. (instead of o.coor gm. of the original) 
was required to kill a guinea-pig of the same weight. To neutralize 0.004 gm. 
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 0.001 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 gm. = 4 minimal lethal doses 
of this modified venom o.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 
