DEXTRINS AND GUMS. 223 



formed, until finally we have sugar and a dextrin, maltodcxtrin, which 

 refuses to split further, as final products. The views are rather contra- 

 dictory in regard to the number of dextrins which occur as intermediate 

 steps. The sugar formed is maltose (or in first place isomaltose), and 

 only very little dextrose is produced. Another view is that first several 

 dextrins are formed consecutively in the successive splittings, by hydra- 

 tion, and then finally the sugar is formed by the splitting of the last 

 dextrin. According to MOREAU, in the first stages of saccharine ation 

 amylodextrin, erythrodextrin, achroodextrin and sugar are formed sim- 

 ultaneously. Other investigators, especially SYNIEWSKI, have recently 

 suggested other views on the subject. 1 



This question has taken another direction by the investigations of 

 MAQUENNE, mentioned above. According to him the amylose passes 

 directly into maltose without the formation of dextrin by the action of 

 malt infusion. The dextrins produced are only formed from the amylo- 

 pectin, which does not undergo saccharification with freshly prepared 

 malt infusions, but only with older or especially active infusions. This 

 also explains why in the older investigations the saccharification was 

 only about 80 per cent while MAQUENNE has been able to completely 

 convert the starch into sugar by en zymotic action. 



The various dextrins are very harcl to isolate as chemical individuals 

 and to separate from each other. YOUNG 2 has tried their separation 

 by means of neutral salts, especially ammonium sulphate, and MOREAU 

 by the aid of a baryta-alcohol method. We cannot enter into the dif- 

 ferences as to the dextrins so separated, and only the characteristic 

 properties and reactions will be given for the dextrins in general. 



The dextrins appear as amorphous, white or yellowish-white powders 

 which are readily soluble in water. Their concentrated solutions are 

 viscid and sticky, like gum solutions. The dextrins are dextrogyrate. 

 They are insoluble or nearly so in alcohol, and insoluble in ether. Watery 

 solutions of dextrins are not precipitated by basic lead acetate. Dex- 

 trins dissolve cupric hydroxide in alkaline liquids, forming a beautiful 

 blue solution, which, as is generally admitted, is reduced by pure dex- 

 trins. According to MOREAU pure dextrin has no reducing action. The 

 dextrins are not directly fermentable. 



The vegetable gums are soluble in water, forming solutions which are viscid 

 but may be filtered. We designate, on the contrary, as vegetable mucilages 



1 In regard to the various views on the theories of the saccharification of starch, 

 see Musculus and Gruber, Zeitschr. f. physiol. Chem., 2; Lintner and Dull, Ber. d. d. 

 chem. Gesellsch., 26 and 28; Brown and Heron, Journ. of Chem. Soc., 1879; Brown 

 and Morris, ibid., 1885 and 1889; Moreau, Biochem. Centralbl., 3, 648; Syniewski, 

 Annal. d. Chem. u. Pharm., 309, and Chem. Centralbl., 1902, 2. 



2 Journ. of Physiol., 22, which contains the older researches of Nasse, Kriiger, 

 Neumeister, Pohl, and Halliburton. Moreau, 1. c. 



