208 THE VENOM OF HELODERMA. 



venom which had been mixed with eosin but had not been heated. It has been 

 previously shown that heloderma venom may be heated to 100 C. without 

 seriously impairing its toxicity. 



In four of the five experiments the animals (in three cases mice, in one case 

 rats) injected with unheated venom mixed with eosin died most rapidly; those 

 injected with venom which had been heated died less rapidly than those injected 

 with the venom mixed with eosin and heated. In one experiment the degree of 

 toxicity of the various venom mixtures was practically the same, independent 

 of whether eosin had or had not been added or whether or not they had been 

 heated. In this experiment the venom was heated to 100 C. for 10 minutes 

 and also to 120 C. for 10 minutes. In spite of the negative result of this one 

 experiment it would appear that the addition of eosin to heloderma venom 

 prevents the slight harmful influence of heat upon the toxicity of the venom, 

 perhaps by diminishing the precipitate which includes a part of the venom. 



Neutral red we found prevented neither heat coagulation nor the slight de- 

 structive influence of heat upon the heloderma venom. On the contrary, the 

 addition of neutral red to venom, even if the mixture was not heated, appeared 

 to lessen the toxicity. We found that mice injected with either heated or 

 unheated venom died about 50 minutes after the injection, while mice injected 

 with either heated or unheated venom to which neutral red had been added 

 died about 1 hour 30 minutes after injection. We have, however, carried out 

 too few experiments with neutral red to enable us to draw any definite conclu- 

 sion as to whether this stain diminishes the toxicity of heloderma venom or not. 



COMBINED INFLUENCE OF LIGHT OR DARKNESS AND VARIOUS 

 STAINS ON VENOM. 



In testing the influence of light or darkness upon mixtures of solutions of 

 venom and various stains we have used eosin, 1 : 500, 1 : 2000, and 1 : 5000 

 and methylene blue 1 : 500 and 1 : 5000. The test-tubes containing the venom 

 were exposed to the diffuse daylight of the room for several days and the con- 

 trols were wrapped in black cloth and kept in a drawer. We have tested the 

 toxicity of the solutions, both those left in the light and those left in the dark, 

 after 2, 4, and 14 or 18 days. 



In every experiment we used fresh heloderma venom diluted with twice its 

 volume of 0.85 per cent sodium-chloride solution and sterilized. To small 

 quantities of this sterilized solution equal quantities of a previously sterilized 

 solution of the stain were added and the tubes placed in previously sterilized 

 tubes, closed with cotton, and sealed with paraffin. In every case duplicate 

 sets of tubes were mixed, so that one might be left in the light and the other in 

 the dark. 



We found no difference between the action of the various dilutions of the 

 same stain. Thus, the action of the 1 : 500 solution was the same as of either 

 the 1 : 2000 solution or the 1 : 5000 solution of eosin. Therefore, in describing 

 the results of these experiments, we shall describe only the experiments carried 

 out with the 1 : 500 eosin solution. 



