STEREO-CHEMISTRY AND PHYSIOLOGY 469 



Much less attention has been given to the physiological 

 action of stereoisomers of this type ; and when we examine 

 the literature of the subject, only a few scattered references 

 are to be found. The cause of this apparent neglect is to be 

 found in the fact that many of the alkaloids used in medicine 

 occur in optically active forms, while geometrically isomeric 

 bodies find no considerable place in pharmacology. 



We may consider in the first place the effect which this 

 type of isomerism exerts upon fungi. The fungus Penicillium 

 glaucum grows readily in fumaric acid solution, but does not 

 thrive in a solution of maleic acid. Using Lupimis albus, L., 

 Kahlenberg and True x established the following figures. 

 When the fungus was introduced into a solution containing 

 116 grammes of acid in 6,400 litres of water, it died. When 

 the solution was diluted to twice its volume, the organisms 

 were able to live in the weakened solution. 116 grammes 

 of maleic acid dissolved in 3,200 litres of water produced a 

 solution incapable of supporting the organisms ; but on dilution 

 to 6,400 litres it became fit to support the fungi. These two 

 sets of results, pointing as they do in opposite ways, seem 

 to indicate a difference in the configurations of the active tissues 

 of fungi, Penicillium glaucum being capable of attacking fumaric 

 acid, Lupinus albus, L., has a greater power of breaking down 

 maleic acid. Further research in this field might lead to very 

 interesting results, as the case seems to form a parallel to the 

 action of ferments upon sugars, with which we have already 

 dealt. 



In toxic action the two acids differ considerably, as Ishizuka 2 

 has proved. In his experiments he took 1*94 grammes of acid 

 for each kilogramme of dog used. This, in the case of maleic 

 acid, proved a fatal dose ; while with fumaric acid the same 

 dose had no effect. It should be noted, however, that this 

 result may be due to a difference in the strength of the 

 two acids, maleic acid being much stronger than fumaric. 



Toxic action, however, is not the only property in which 

 these isomers show differences. It has been found that in 

 the case of the compound benzyl-/3-amidocrotonic ester, whose 

 two configurations are shown below, the one form (M.P. 79 ) 

 is tasteless, while its isomer (M.P. 21 ) has an intensely sweet 



1 Kahlenberg and True, Botanical Gazette, Chicago, 22, 181 (1896). 



2 Ishizuka, Bull. Coll. Agr., Tokyo, 2, 484 (1897). 



