462 SCIENCE PROGRESS 



upon the special arrangement of groups around the nitrogen 

 atom. Whichever be true, the isomerism of tropine and pseudo- 

 tropine is caused by spacial, not structural differences. When 

 we allow mandelic acid to react with the hydroxyl groups of 

 tropine and pseudo-tropine, we obtain two stereoisomeric 

 esters, each of which has the following structure : 



CH., CH CHj 



I " I 

 C6H,.CH0H.C0.0CH N.CH, 



CH, CH CHo 



The ester obtained from tropine has a strong mydriatic action, 

 while the pseudo-tropine ester has no such property. 



When one of the hydrogen atoms of tropine is replaced by 

 a carboxyl group, tropine carboxylic acid is formed ; and when 

 the alcoholic radicle of this substance is benzoylated while the 

 carboxyl group is esterified with methyl alcohol, we obtain 

 cocaine, which has the formula : 



CH, 



CfiHs.CO.O.CH 



CH, CH ^CHj 



Cocaine, of course, since it contains asymmetric carbon atoms, 

 exists in two antipodic forms of equal and opposite rotatory 

 power. Poulsson ^ found that when applied to the tongue 

 the paralysing action of dextro cocaine was stronger and set 

 in more rapidly than that of laevo cocaine ; but, on the other 

 hand, the effect of the dextro isomer was not so permanent as 

 that of the laevo antipode. In the case of rabbits and frogs, 

 the fatal dose seems to be the same for each isomer. Ehrlich 

 and Einhorn- arrived at similar results. 



According to Hesse ^ the therapeutic action of scopolamine 

 and the corresponding racemic compound atroscine differ from 

 each other. 



Cushny* investigated the actions of laevo hyoscyamine and 



* Poulsson, Archiv exp. Path. u. Phannak.^ 27, 309 (1890). 



* Ehrlich and Einhorn, Ber.^ 27, 1870 (1894). 



' Yitsst, Jourfi. f. praki. Chem., [2 J, 64, 353 (1901). 



* Qnshny, Journ. Physiol., 30, 193 (1904). 



\ 



