ACID FERMENTATIONS. 353 



hardly necessary to enumerate the whole of these species. Experi- 

 ments of this kind were commenced by DUCLAUX (XXI.) in 1883 

 with Asp. niger, and afterwards with A. glaucus, "Penicillium 

 glaucum" and Allescheria Gayoni (Eurotium Gayoni}, by FERNBACH 

 (HI.), Bourquelot, HEBEBRAND (I.), LABORDE (VI.), and WEHMER 

 (V.). Observations on the saccharifying properties of extracts 

 from the mould vegetations have recently been communicated by 

 SCHAFFER (IV.), with regard to a number of species (Aspergillus 

 niger, A. Wentii, A. fumigatas, A. glaucus, A. or y zee, Penicillium 

 glaucum, P. luteum, P. italicum, and P.rubrum. 



FERNBACH (IV.) and Bourquelot isolated from the cultures or 

 growths of Asp. niger the amylase (diastase) previously mentioned 

 by DUCLAUX (XXII.). The first-named worker also found that 

 the preparation obtained by precipitation with alcohol has its 

 activity seriously impaired by even small quantities of free organic 

 or inorganic acids. This may also explain the circumstance, ob- 

 served by WEHMER (V.) that the liquefaction of starch by this 

 fungus (which produces free oxalic acid), is sometimes incomplete. 

 DUCLAUX (XXII.) states that the fungus will also corrode and 

 dissolve raw starch by means of a maltase differing from the 

 ordinary kind, dextrose being formed. According to LABORDE (VI.), 

 the enzyme in question (amylomaltase) from Asp. niger, Penicillium 

 glaucum, and Allescheria Gayoni, is able to transform starch directly 

 into dextrin and dextrose, and not, as in the case of malt diastase, 

 into maltose which substance it is also able to hydrolyse. In this 

 author's opinion (which, however, has not been left unchallenged), 

 the amylomalbase secreted by these three fungi is not only different 

 from the maltase of barley malt, but is also a different substance 

 in each case, a conclusion formed on the basis of comparative be- 

 haviour under external influences, such as the action of acids and 

 the optimum and maximum effect produced. This point, how- 

 ever, needs further investigation. PETIT (IV.) states that both 

 Penicillium and Aspergillus also convert into dextrose the dextrin 

 (QjjH^OjJj formed during the saccharification of malt. HEBEBRAND 

 (I.) has written on the diastase of Penicillium ; and Gosio (VII.) 

 on Penicillium brevicaule, which also saccharifies starch. 



With regard to the conditions under which diastase is formed 

 by Asp. niger and Pen. glaucum, reference may be made to p. 62, 

 vol. ii. The continuous production of amylase in cultures of Asp. 

 niger on sugar solution \vas assumed in 1889 by Duclaux, but no 

 proof was advanced ; so that the work of this experimenter, fruit- 

 ful as it was, affords no experimental proof of the various new 

 statements. 



291. Acid Fermentations. 



In contrast with the various enzyme actions of the Aspergillacece, 

 the production of free organic acids the sole process to which we 



