158 THE CARBOHYDRATES 



the six corners of the hexagon ; such a molecule would yield on 

 hydrolysis 3 molecules of maltose, ab, cd, and ef, which is in 

 agreement with the observed fact that amylose yields only 

 maltose. 



Action of Bacteria on Starch. 



In 1903 Schardinger * isolated from retting flax a bacillus 

 to which he gave the name Bacillus macerans ; this organism 

 when grown on 5 per cent starch paste, liquefies the starch 

 and sets up an active fermentation with the evolution of 

 carbon dioxide and hydrogen, and the production of acetone f 

 and butyl alcohol. In the course of a few days these products 

 give way to the formation of acids, and after about a week 

 a liquid remains from which Schardinger isolated two crystal- 

 line substances which he described as a- and ^-dextrin. The 

 former of these gives with iodine a dark green compound 

 crystallizing in needles, while the latter gives dark reddish- 

 brown prisms. Schardinger ascribed to these compoimds the 

 formulae (C6Hio05)4 and (C6Hio05)6 and named them tetra- 

 and hexa-amylose respectively. Pringsheim and his colla- 

 borators X subsequently investigated these compounds more 

 fully and found that on treating them with acetic anhydride 

 and zinc chloride they were acetylated and at the same time 

 depolymerized ; the product obtained from the a-dextrin 

 (C6Hio05)4 was shown to be an acetylated diamylose (C6Hio05)2, 

 while that obtained from the ^-dextrin (C6Hio05)6 was a 

 triamylose (C6Hio05)3. For these reasons he regarded Schar- 

 dinger's a- and jS-dextrin as polymerized di- and triamyloses 

 respectively as shown by the formulae — 



a-Dextrin — Tetra-amylose [(CeHio05)2]2 



Diamylose {C^Yiiffd^)^ 

 j3-Dextrin = Hexa-araylose [(CsHio05)3]2 



Triamylose (CgH,oOB)3 



* Schardinger : " Zeit. Nahr. Genussm.," 1903, 6, 874 ; " Zentr. Bakt. 

 Parasitenk.," 1905, [ii], 14, 772 ; 191 1, 29, 188. 



t During the Great War this type of fermentation was first employed 

 on a large scale for the production of acetone. 



X Pringsheim and Langhans : " Ber. deut. chem. Ges.," 1912, 45, 

 2533 ; Pringsheim and Eissler : id., 191 3, 46, 2959. 



