514 CHEMISTRY OF ALCOHOLIC FERMENTATION. 



Whether c?-galactose also formerly termed lactose (not to be 

 confounded with the di-saccharide lactose, or milk sugar, of the 

 existing nomenclature) and lactoglycose actually occurs in a 

 free state in nature has not yet been definitely ascertained. In 

 combination with c-glucose it forms milk sugar and melibiose. 

 In the vegetable kingdom, d-galactose is found as a constituent of 

 several glucosides, and especially of the widespread galactans, 

 which may be divided into simple and conjugate galactans. True 

 galactans are met with in barley, malt, and numerous seeds, and, 

 according to PRINSEN.GEERLIGS (V.) and E. O. von LIPMANN (III.), 

 also in the products and waste products of the cane-sugar and beet- 

 sugar industries. According to PAYEN (III.) and BAUER (II.), ge- 

 lose, the chief constituent of agar-agar, consists mainly of galactan. 

 Conjugate galactans occur in vegetable mucilages : in yeast gum 

 according to SCHUTZENBERGER (III.), as galactoarabans in various 

 seeds, according to E. SCHULZE (V.), whilst LiNTNER(VIII.)states 

 that galactoxylan is a constituent of wheat, barley and malt. 

 Conjugate galactans, differing with the origin of the material, are 

 found in gum arabic. These bodies are also met with in the 

 animal kingdom : associated with milk sugar in milk, according 

 to B^CHAMP (XV.) ; whilst according to THUDICHUM (I.) they 

 form a constituent of protagon. LINDNER (XLII.) states that 

 d-galactose is fermented by all yeasts that dissociate d- glucose, 

 except the following species : Sacch. membrancefaciens, St fari- 

 nosus, /S. Bailii, S. apiculatus, Schizos. Pombe, Schizos. mellacei, as 

 well as a few yeasts from gall fermentation and cucumber pickle. 

 On the other hand, strangely enough, it is fermented by two 

 film-producing budding fungi (Nos. 127 and 374 of the Berlin 

 collection) which leave glucose, mannose, and fructose intact. 

 This report urgently needs confirmation, since the older state- 

 ments on the fermentability of c?-galactose are more divergent 

 than in the case of any other sugar. It would occupy too much 

 space to detail the communications on this point, and the reader 

 is therefore referred to BAU'S work (XXIII.), in which the older 

 literature was critically reviewed. According to E. Fischer, 

 galactose is fermented by the culture yeasts, by S. pastorianus 

 I. II. and ///., S. ellipsoideus I. and //., and S. Marxianus, as 

 well as by milk-sugar yeast, whereas no fermentation is set up by 

 S. membrancefaciens and S. productivns. KOZAI (II.) reports 

 that sake yeast will also ferment galactose. 



Whilst the above three sugars of the hexose group are aldoses, 

 the following representative of the ketohexoses must be added : 

 cZ-fructose (levulose or fruit sugar), which is very widespread in 

 nature and almost invariably accompanies cZ-glucose. A mixture 

 of these two sugars in equal parts constitutes invert sugar, which 

 term is also applied to their mixtures in any proportion. Fruit 

 sugar is a constituent of several polysaccharides, including saccha- 

 rose, melitriose, lupeose, stachyose, &c., of inulin and allied sub- 



