154 E-155.] 



DEXTROSE 



247 



when the former is in excess (Ibid. 14, 

 162 j 203 ; Prinsen Geerligs, Ch. Centr. 

 1898, 1, 713). 



[F.] Mannose [156], under the in- 

 fluence of dilute alkali as above, gives 

 dextrose with Isevulose and other sugars 

 (Lobry de Bruyn and Van Eckenstein, 

 loc. cif. 14, 98; 156; 203; 16, 257; 

 274; Ber. 28,3078). 



[G.] d- G laconic acid [Vol. II] lactone 

 gives glucose on reduction with sodium 

 amalgam in acid solution (Fischer, Ber. 

 22, 2204 23, 804 : also A above). 



155. laevulose; d-Fructose ; 

 Fruit Sugar ; Hexanepentolone. 



H HO HO 



HO . H a C . CO- 



-CH,.OH 



HO H II 



NATURAL SOURCES. 



Occurs throughout the vegetable 

 kingdom associated with dextrose. It 

 accompanies dextrose also in honey (see 

 under dextrose for references). 



The sweet pods of the ' mesquit tree/ 

 Prosopis (hilcis, from N. and S. America 

 contain over 5 per cent, of Isevulose, but 

 no dextrose (Steel, Rep. Aust. Assoc. 

 1 898, p. 946). Invert sugar is contained 

 in the mahwa-flowers from Bassia lati- 

 folia (see under dextrose). Manna (see 

 under dextrose) contains 2-5-3-4 per 

 cent, of Isevulose, arising probably from 

 the hydrolysis of manneotetrose. (see 

 below: Tanret, Bull. Soc. [3] 27, 



947)- 



The yeasts, moulds, and Bacteria 

 capable of hydrolysing or ' inverting ' 

 saccharose may be regarded as bio- 

 chemical producers of Isevulose from 

 the C 12 -sugar (see under dextrose). 

 Yeast allowed to infuse in chloroform 

 water gives a 1-sugar, apparently Isevu- 

 lose (Salkowski, Zeit. physiol. Ch. 13, 

 506). 



Saccharose is fermented by Leuconos- 

 toc mesenteroides with the formation of 

 dextran and laevulose (Van Tieghem, 

 Jahresber. d. Agrikulturch. 1879, 544). 



Lsevulose is produced from mannitol 



by Bacterium aceti and B. xylimim 

 (A. J. Brown, Trans. Ch. Soc. 49, 182 ; 

 51, 638). B. aceti of Hansen resembles 

 B. aceti of Brown in its action on 

 mannitol (Seifert, Ch. Centr. 1897, 2, 

 871). 



The sorbose bacterium ( = B. xylinum, 

 according to Emmerling) produces Isevu- 

 lose from mannitol (Vincent and Dela- 

 chanal, Comp. Rend. 125, 716; Ber- 

 trand, Ibid. 126, 763). Mannitol is 

 not oxidised by Bacterium pasteurianuw , 

 and is only converted slowly into Isevu- 

 lose by B. kiitzingianum (Seifert, Ch. 

 Centr. 1897, 2, 871 ; Bied. Centr. 27, 

 123; Joura. Ch. Soc. 74, II, 399; 

 Mayer, Journ. Fed. Inst. 4, 666). 



Raffinose (melitriose) is hydrolysed 

 by high fermentation yeasts to meli- 

 biose and Isevulose, while low fermenta- 

 tion yeasts produce dextrose, Isevulose, 

 and d-galactose. The yeasts investi- 

 gated were Frohberg and Saatz, Sac- 

 charomyces cerevisia, S. ellipsoideus, S. 

 pastorianus, S. logos, S. marxianus, S. 

 anomalus, Sckizosaccfi . pombe, and the 

 kefir ferment. S. apiculatus does not 

 resolve raffinose (Bau, Ch. Centr. 1898, 

 2, 682 ; Journ. Fed. Inst. 4, 644). 



Raffinose is inverted and finally com- 

 pletely assimilated by dtpergillv* niger 

 (Gillot, Bull. Acad. Roy. Belg. 1899, 

 p. 21l). In a solution of raffinose in 

 presence of a mineral acid Penicillium 

 glaucum also causes inversion (Ibid. 

 1900, p. 99). 



Gentianose, from gentian root, gives 

 Isevulose on hydrolysis (see under dex- 

 trose for reference). 



Inulin, a carbohydrate related to 

 starch and found in many plants as 

 a reserve material, is resolved by the 

 enzyme known as inulase into laevulose. 

 (According to Tanret, Bull. Soc. [3] 9, 

 227, some dextrose is also formed by 

 ordinary hydrolysis.) Inulase is found 

 in Aspergillus niger (see J. R. Green's 

 ' Fermentation/ Chap. VI ; also Bour- 

 quelot, Comp. Rend. 116, 1143), as well 

 as in association with inulin in various 

 tubers, bulbs, &c. 



Lsevomannan, a complex poly?ac- 

 charide obtained from the ivory-nut 

 (PhytclepJtas macrocarpa), gives Isevulose 

 and mannose on hydrolysis (Baker and 



