58 THE VENOM OF HELODERMA. 



Sterile Venom. 



Rat 96, 120 g. 



JUNE 17, 12 h 05 m injected intraperitoneally 0.1 c.c. venom. l h 30 m found dead. 

 Mouse 17. 



JUNE 17, 12 h 2S m injected intraperitoneally 0.01 c.c. venom. l h 30 m found dead. 

 Not Sterile Venom. 



Rat 97, 120 g. 



JUNE 17, 12* 08 m injected intraperitoneally 0.1 c.c. venom. l h 30 m living; sick. 



2 h 45 dead. 

 Mouse 18. 



JUNE 17, 12* 31 m injected intraperitoneally 0.01 c.c. venom. l h 30 m living; very 

 sick. 2 o'clock dying; killed. 



Other experiments were also carried out with venom which had been 

 treated in a similar manner, that is, sterilized and kept at room temperature. 

 This venom was tested 2, 7, and 21 days after sterilization, and it was found 

 that while it had lost part of its toxicity it had lost far less than the unsterilized 

 venom which was kept on ice. Thus, on the day the venom was sterilized, 

 0.005 c.c. of unheated venom killed a mouse in from 25 minutes to 4 hours 30 

 minutes; 2 days later, 0.005 c.c. of sterilized venom killed a mouse in 8 hours; 

 7 days later, 0.01 c.c. of unsterilized venom killed a mouse in 24 hours, while a 

 similar quantity of sterilized venom killed in 6 hours; 21 days after the sterili- 

 zation, 0.03 c.c. of the sterilized venom killed a mouse in 40 minutes, while the 

 same quantity of the unsterilized venom killed in 24 hours. 



In other experiments the venom, after being sterilized, was placed in the 

 thermostat and kept at a temperature of 37. 5 C. instead of being kept at room 

 temperature. In these experiments also it was noted that the sterilized venom 

 kept better than the unsterilized venom. However, in all cases, the toxicity of 

 the venom when it had been dissolved diminished slightly after some time, even 

 though it had been sterilized. 



Furthermore, we tested the power of thymol to prevent the deleterious 

 effect on venom of bacteria and of standing in solution. We found that at 

 periods 2, 7, and 21 or 23 days after mixing, unsterilized venom to which thymol 

 had been added had lost its toxicity in much the same degree as unsterilized 

 venom to which no thymol had been added. Sterilized venom, to which thy- 

 mol had been added, acted in much the same manner as the simple sterilized 

 venom ; that is, became very slightly less toxic after several days. 



Thus we note that unsterilized venom in solution loses its toxicity fairly 

 rapidly because of bacterial action. Sterilized venom in solution loses in toxic- 

 ity far more slowly, and here the loss of toxicity is probably due to the gradual 

 decomposition of the venom when kept in solution. The addition of thymol 

 does not appear to prevent the destruction of the venom, which, in spite of the 

 thymol, loses its toxicity as rapidly as unsterilized venom. 



EFFECT OF DIALYZING. 



The venom passes through parchment paper rather slowly. In our experi- 

 ments venom was diluted to ten times its original volume with physiological 

 salt solution, sterilized and put to dialyze against twice its volume of sterile 

 salt solution. The whole apparatus (made as sterile as possible) was kept 

 directly on ice. In 4J days the longest period that we tried dialysis of the 



