104 



AH \M METRIC ANALYSIS 



^ 0.020 - 



o 



c 



0.010 



0) 



o 



c 



o 



o 



2.0 - 



0.00340 



0.00350 



Reciprocal of absolute temperature 

 Fig. 12. Effect of temperature on the killing rate of the fish Lciicis- 

 ciis idus by the optical isomers of nicotine. The lower graph represents 

 the killing rate plotted logarithmically. (From Cause and Smarag- 

 dova, 1939.) 



mately isotoxic concentrations of the isomers, i.e., 0.007% 

 for 1-nicotine and 0.014% for d-nicotine, were used. The 

 temperature characteristics of the two isomers are prac- 

 tically identical: in the d-form \i = 37,500, and in the 

 1-form pi = 36,800. Such an identity of temperature char- 

 acteristics was also observed in experiments with tad- 

 poles; in the d-nicotine \x = 14,400, and in the 1-nicotine 

 |ii ^ 14,600. Hence the relation of toxic action to temper- 

 ature strongly supports the view that the mechanism of 

 toxic action is identical in the two optically isomeric 

 nicotines. 



The same relations, that is, (1) a high toxicity of the 

 natural isomers, (2) the same relation between the in- 



