I20 THE CARBOHYDRATES 



amygdalin *; as the result of its synthesis f and from other 

 considerations its constitution may be represented by the 

 formula — 



i ° 1 i ° 1 



CHOH . (CHOH)3 . CH . CH^ . O . CH . (CHOH)3 . CH . CHjOH 



from which it appears to be a j8-glucosido-6-glucose. 



TREHALOSE. C^^K.^O^i. 



Trehalose is a disaccharide very widely distributed among 

 the fungi, J including ergot and myxomycetes,§ in moulds 

 such as Aspergillus niger, in Selaginella lepidophylla \\ and in 

 various Florideae.^ It does not reduce Fehling's solution and 

 is strongly dextro-rotatory, ap = + 199°. When boiled with 

 5 per cent sulphuric acid for six hours, it is converted into 

 two molecules of glucose.** It is also hydrolysed by the 

 enzyme trehalase contained in many fungi. 



LACTOSE OR MILK SUGAR. Cy^R-^fi^i. 

 This disaccharide, though of considerable importance in 

 the animal kingdom, is never found in plants. It reduces 

 Fehling's solution and on hydrolysis, by the enzyme lactase or 

 by dilute mineral acids, it yields molecular proportions of 

 glucose and galactose. 



MELIBIOSE. CiaH^jjOu. 

 This disaccharide ff is not a naturally occurring sugar, but 

 is produced by the partial hydrolysis of the trisaccharide 

 raffinose ; it is dextro-rotatory, a^ = + 143°. It yields on 

 hydrolysis molecular proportions of glucose and galactose. 

 Owing to the fact that this sugar is hydrolysed by bottom 

 fermentation yeasts but not by top fermentation yeasts, it 



* Haworth and Wylam : " J. Chem. Soc." 1923, 33, 3120. 



t Iwanoff : " Biochem. Zeit.," 1925, 162, 455. 



JBourquelot : " Bull. soc. mycol. France," 1905. 21, 50. 



§ Helferich, Bauer, and Weigand : " Annalen," 1926, 447, 27. 



II Anselmino and Gilg : " Pharm. Zeit.," 1913, 58, 563 ; Lippmann : 

 " Ber. deut. chem. Gesells.," 1912, 45, 343i- 



^ Kylin : "Zeit. physiol. Chem.," 1915, 94, 337. 



** Winterstein : id., 1894, 19, 70. 



tt Scheibler and Mittelmeier : " Ber. deut. chem. Gesells.," 1890, 23, 

 1438. 



