210 THE VENOM OF HELODERMA. 



more easily destroyed by heat than cobra venom, is also more rapidly and fully 

 destroyed by the photodynamic action of eosin. 



The toxins of heloderma venom, which are relatively thermostable, are 

 not easily destroyed by the photodynamic activity of eosin, since it requires 

 several days for the eosin to destroy the toxic properties of this venom. 



SUMMARY. 



1. The addition of 0.5 per cent solution of eosin to freshly diluted and fil- 

 tered venom in the proportion of 0.15 c.c. of eosin solution to 0.85 c.c. venom- 

 sodium-chloride solution prevents the formation of a coagulum even when the 

 venom is heated to 100 C. for 10 minutes. 



2. The addition of neutral red to venom does not prevent the formation 

 of a coagulum. 



3. The addition of eosin to venom prevents the slight decrease in the toxic- 

 ity of venom usually resulting from heating the venom to 100C. It is prob- 

 able that neutral red has no similar action. 



4. The addition of eosin (1 : 500, 1 : 2000, or 1 : 5000) or of methylene blue 

 (1 : 500, or 1 : 5000) to fresh diluted venom does not influence the toxicity of 

 such venom even after a period of 14 or 18 days if the venom is kept in the dark. 



5. If, however, eosin (1:500, 1:2000, or 1:5000) or methylene blue 

 (1 : 500 or 1 : 5000) be added to venom and this mixture be exposed to the 

 light, the venom gradually loses its toxic properties and after 14 or 18 days 

 seems to have lost all toxicity. 



