OPTICAL ACTIVITY OF BIOL. MATERIAL 25 



TABLE 3 



Content of Optically Active and of Racemic Malic Acid, in ml. of 



Molar Acid Solution per gr. of Dry Weight, in Leaves 



OF Different Plants (Schwarze, 1932) 



Nicotiana tabacuvi .. 

 Pelargonium zonule 

 P. peltatiini 



Pub IIS iclaeiis 



According to Rulilancl and Wetzel, the newly formed 

 malic acid is always optically active and only later does it 

 pass into the racemic form. In Rheum liyhridum, laevo- 

 rotatory acid was found to be racemised after the newly 

 formed portions of it had penetrated into the roots. 



Bendrat (1929) observed that all malic acid, in the plant 

 Sempervivum glaucum, is in the racemic form in the even- 

 ing, that it increases during the night, and that, after this 

 increase one can find some laevorotatory acid, in the morn- 

 ing (Table 4). It seems, then, that the optically active 

 form appears in metabolic processes and that it is race- 

 mised later. ■ 



TABLE 4 



Content of Total and Laevorotatory Malic Acid, in ml. of Molar 



Acid Solution per gr. of Dry Weight, in the Middle 



Leaves of Sempervivum glaucum (Bendrat, 1929) 



Total malic l-malic 



acid acid 



Evening 0.140 



Morning 0.194 0.013 



Data on other organic acids, though incomplete, agree 

 in general with the observations just mentioned. Thus it 

 was known to Pasteur that d-tartaric acid as well as dl- 

 tartaric acid are present in grape juice (see Thiele, 1911). 



Inactive lactic acid has been found in the leaves of the 

 common ash, Fraximis excelsior (Gintl, 1869) and in a 

 number of other plants (Stoklasa, 1907). 



