SACCIIARIFICATION OF STARCH. 351 



mentations have been noted in several species, namely : oxalic acid 

 fermentation by Asp. niger, citric acid fermentation by Citromyces 

 Pfefferianus, Citr. g 'aber and Penicillium luteum. Whether these 

 phenomena are separable from the living fungus and can be 

 produced by the lifeless substance has not yet been investigated. 



The dissociation of raceinic compounds into their optically 

 active components by micro-organisms has been already dealt with 

 in vol. i. chap. xxii. The circumstance is only referred to now 

 because nearly all the determinations were made by the help of 

 Aspergillacece, more particularly Asp. niger and " Penicillium 

 glaucum," though in many cases the purity and identity of the 

 species may be doubted. Several experimenters have also worked 

 with Asp. Jtavescens (probably A. flavus) and A. griseus, the latter 

 name possibly masking the identity of some better-known species 

 (e.g., A .fumigatus, Fres.). Unfortunately, descriptions of the fungi 

 are lacking, so that the results are practically worthless. Attention 

 has already been drawn to the circumstance that the Penicillium 

 glaitcum, of the earlier workers was an imperfectly identified species, 

 and can only be regarded as a collective term applied to green 

 moulds of indefinite nature. 



Our knowledge of the pigments produced by several of the 

 species, and the conditions under which these pigments are 

 developed, is still in an imperfect state. The same also applies 

 to the poisons formed by the pathogenic species, though the 

 less important decomposing action of several species on readily 

 oxidisable substances (alcohols and organic acids) has been 

 repeatedly examined. The chemical activity of our fungi is 

 almost invariably connected with the presence of atmospheric 

 oxygen, submerged vegetations being unable to bear the complete 

 exclusion of oxygen for more than a short time, even when sugar 

 is administered. Further particulars of the processes are given 

 by PFEFFER (III.) and DUCLAUX (XXI.), in the lectures on plant 

 physiology by JOST (I.), and in CZAPEK'S (IV.) recently published 

 work on the biochemistry of plants. 



290. Saecharifieation of Starch. 



The diastatic property of the Aspergillacece is rightly placed in 

 the foreground as the one of greatest practical importance. It 

 has been utilised technically from the oldest times ; and special 

 historical interest attaches to the diastase of the Japanese Asper- 

 gillus oryzce, this being the first enzyme from thread fungi to 

 become better known, and forming the pioneer of the long series of 

 fungus enzymes discovered during the last two decades of the nine- 

 teenth century. In 1 860, Berthelot isolated yeast invertase, and 

 the property of inverting saccharose, possessed by the extract from 

 "mould fungi," was mentioned in 1864 by Bechamp. After 

 Gayon's discovery of the inverting action of Asp. niger in 1878, 

 VOL. ii : PT. 2 z 



