( 375 ) 



of Fun^i in which so often acids are formed and of the nocturnal 

 production of acids in Crassulaceae, in which according to more 

 recent investigations the formation of acid may be connected with 

 the decomposition of carbohydrates ^). The question now is, what 

 acids are formed in the decomposition of glucose by the enzyme of 

 Sauromatum venosum ? 



The quantity of liquid which was not required for the other 

 experiments was evaporated, extracted with ether and the ethereal 

 extract used for further investigations. The small quantity available 

 was not sufücient for macrochemical investigation, I therefore 

 made the analysis in about the same way as that described by 

 H. Behrens *). 



The ether was distilled off and water added. First of all I tried, 

 whether the acid was volatile with steam, this turned out not to be 

 the case, only a minute quantity passed over, too small for further 

 investigation. Moreover the liquid had already boiled for a few 

 minutes as described above, and the odour then indicated traces of 

 butyric acid. 



The acid reaction is therefore not caused by formic, acetic or 

 propionic acid, nor by higher fatty acids. 



By sublimation on a microscopic slide a sublimate was only obtained 

 at a fairly high temperature, when the substance was coloured brown. 

 The sublimate was not crystalline even when breathed on, so that it 

 cannot be oxalic or succinic acid. The test with lead acetate for 

 malonic acid yielded an equally negative result. 



On the other hand the aqueous solution gave distinctly Berg's 

 test '^ i. e. a yellow colouration with a solution of two drops FeClj 

 45° B and two drops HCl 22° B in 100 c.c. water. This reaction is 

 peculiar to organic acids with one or more CHOH groups, oxyacids 

 therefore of which the best known are lactic, tartaric, malic and 

 citric acid. 



The test for cobaltolead lactate as well as for potassium and 

 silverbitartrate gave a negative result, the two first mentioned acids 

 are absent. On the other hand, testing with AgNO^ , there was proof 

 of the presence of citric acid, as shown by the crystals of silver 



1) Hugo de Vries. Verb. Konink Akad. v. Wet. 1884. 



G. Kraus. Abhandl. naturf. Ges. Halle 1884. 



0. Warburg. Unters. bot. Inst. Tubingen 1886. 



A. Mayer. Landw. Versuchsst. 1887. 



K. PuRiEwiTSCH. Bot. Gentr. 1894. 

 •) H. Behrens. An), zur mikrochem. Analyse 4e Heft 1897. 

 3j Bekg et Gerber. Bull. soc. chim. 1896. 



