ASYMMKTIi'lC AX ALT SIS 117 



farther, the selective action of nicotine is traced readily, 

 as for example in PaJaeniou". Greenwood writes fui'ther 

 that: ''Animals which have enough in common to stand 

 near each other in classification, may yet react differently 

 to nicotine, each according to what I may perhaps call 

 its own balance of organisation." 



Gause and Smaragdova (1939) made quantitative de- 

 terminations of the toxic action of the two optically 

 isomeric nicotines. The advantage of the use of the two 

 isomers will appear in the discussion of the results. 



Experiments on vertebrates showed that the stereo- 

 coefficients of toxic action of optical isomers of nicotine 

 (a) are of the same order of magnitude in all ;ininials 

 studied : 



Bird (AcanfJtis flaminra) a = 3.1 



Lizard {Lacerta viridis) a = 2.4 



Tadpoles {Rana temporaria) a = 3.0 

 Fish (Leuclscus idus) a = 2.9 



Fish {Lebisfes reticulatus) a = 2.4 



Mean a = 2.8 

 Inasmuch as the mechanism of toxic action is identical 

 in optically isomeric nicotines, one can, by the difference 

 of their effects, judge of the difference in spatial proper- 

 ties of the specific receptive substance assumed. As the 

 difference of effects remains constant, one can conclude 

 that the chemical nature of the receptive substance in 

 the vertebrates also remain essentially constant. 



Since the procedure for the introduction of nicotine 

 was not the same for all the animals used — the poison 

 was introduced in the muscle of Lacerta while Lehistes 

 were immersed in the solutions of nicotine — the identity 

 of the stereo-coeffcient is an experimental proof that the 

 conditions of the penetration of nicotine do not affect 

 significantly either the mechanism of toxic action or the 

 reaction of the specific receptive substance. 



Furthermore, the absolute sensitiveness to nicotine 

 in Acanihis is considerably higher than in Lacerta (0.8 



