INFLUENCE OP VARIOUS STAINS UPON VENOM. 209 



We found in the majority of experiments that two days after mixing the 

 eosin and venom the venom left in the dark had lost little if any of the toxicity 

 ■when tested by injections into mice. The venom which had been exposed to 

 the light, however, had lost a considerable part of its toxicity; when a quantity 

 equal to one lethal dose was injected, the animal usually survived; frequently 

 even the injection of a quantity equal to two and a half lethal doses produced 

 no effect, but when a quantity equal to five lethal doses was injected the mice 

 died. 



Four days after the venom and eosin had been mixed, we occasionally 

 noted a weakening of the venom which had been left in the darkness; the toxic- 

 ity was not lost, but the mice lived longer after the injection. In most cases, 

 however, no change was noted. The venom which had been exposed to the 

 light had lost somewhat more of its toxicity; when a quantity equal to two and 

 a half lethal doses was injected the mice did not die, but succumbed when a 

 quantity equal to five lethal doses was injected. 



After 14 or 18 days we usually found no change in the venom which had 

 been left in the dark, while the mixture of venom and eosin which had been 

 exposed to the light was not toxic for mice, even though a quantity equal to five 

 lethal doses was injected. The two different dilutions of methylene blue, like 

 the various dilutions of eosin, both acted in the same manner. 



Two days after mixing the venom and methylene blue the specimens 

 exposed to light were not lethal for mice, though a quantity equal to one lethal 

 dose was injected; at this time the injection of two and a half lethal doses of 

 the venom-methylene-blue solution exposed to light was able to cause the death 

 of the mouse. The mixtures which had been left in the dark had lost none of 

 their activity. 



After four days no further change was noted. The injection of two and 

 a half lethal doses of the venom-methylene-blue solution exposed to light was 

 still lethal for mice. 



After 14 or 18 days the mixtures left in the darkhad lost little if any of their 

 toxic properties. The mixtures left in the light had lost their toxicity and the 

 injection of a quantity of venom-methylene-blue solution which had been 

 exposed to the light, equal to five lethal doses, did not have any effect upon 

 mice. 



Noguchi* found that eosin affects the hemolytic and toxic properties of 

 cobra, daboia, and rattlesnake venom when these are mixed with the stain and 

 exposed to sunlight for 30 hours. The destructive action was most marked 

 when the photodynamic action of eosin was tested with rattlesnake and least 

 marked when tested with cobra venom. Indeed, rattlesnake venom lost 

 almost entirely its toxic properties after 8 hours' exposure to the photodynamic 

 action of eosin. Erythrosin possessed a slightly destructive action on the toxins 

 of these same snake venoms, but its action was much weaker than that of eosin. 



It appears that these venoms react to the photodynamic activity of eosin 

 in much the same manner as they react to heat. Rattlesnake venom, which is 



•Noguchi. Jour, Exper. Med., 1906, vm, 252. 



