ERYTHRODEXTRIN, ACHROODEXTRIN, GRENZDEXTRTN, ETC. 



123 



(2) Erythrodextrin. It differs from starch in that it is soluble in cokl water, is not gran- 



uhir, and because in solid form or in solution it gives only a red color with iodine. 

 Both soluble starch autl erythrodextrin they found to be readily affected by diastase. 

 They did not succeed in obtaining pure erythrodextrin. 



(3) Achroudexfrin a. This does not give a color reaction with iodine. It is more easily 



converted into sugar by diastase than either soluble starch or erythrodextrin. Its 

 rotatory power is (a) = +210, and its reducing power 12. 



(4) Achroodextrin /?. It is unaffected by diastase. Its rotatory power is (a) = +190, and 



its reducing power 12. 



(5) Achroodextrin y. It also is unaffecteil l)y diastase. Its rotatory power is (a) = +150, 



and its reducing power 28. 

 (G) Maltose. Formula, C12H22O11+H2O. Rotatory power (tt) = +150, and its reduchig 



power 66. It is not affected by diastase. 

 (7) Glucose. Formula C6H12O6+H2O. Its rotatory power is (o) = +56, and its reducing 



power 100. It does not undergo fermentation. 



The figures for the rotatory and reducing powers are stated to be only approximate, 

 but they show a decrease of the former and an increase of the latter as decomposition 

 proceeds, with the formation of substances of less molecular weight. Musculus and Gruber 

 write that starch, before it appears in the form glucose, is changed into 5 isomerous bodies, 

 i.e., erytlu'odextrin, achroodextrin a, achi-oodextrin (3, achroodextrin r, and maltose. They 

 regard the starch substance as having the formula ?i (CioHooOio), in which nhas a value 

 of not less than 5 or 6. Starch by absorption of water, by the addition of diastase or dilute 

 acids, undergoes repeated splitting. At each subsequent splitting there appears besides 

 maltose a new dextrin of less molecular weight than the preceding dextrin, that is, n becomes 

 smaller at every stage until achroodextrin ;' results. The latter, through simple absorption 

 of water, goes over into maltose, and by hydration and splitting this goes into 2 molecules 

 of glucose. 



In 1879, Brown and Heron (Proc. Chem. Soc. Trans., 1879, xli, 596; Ann. d. Chem. 

 u. Pharm., 1879, cxcix, 241), while accepting the theory of Musculus and Gruber of 

 the breaking down of the starch-molecule by a series of hydrations and splitting-up 

 processes, stated their belief that the starch- 

 molecule can not have a simpler formula Table 7. 

 than 10 (Ci2HooOxo) and that the first ac- 

 tion of diastase is to separate by hydration 

 one of these 10 groups, which is trans- 

 formed into maltose, while the remaining 9 

 groups constitute the erythrodextrin a, or 

 the first of the series of dextrins. By the 

 addition of more water this dextrin is con- 

 ceived to be spUt into maltose and another 

 dextrin, erytln'odextrin /S, which consists of 

 8 groups. This in turn by hydration is split 

 into maltose and another dextrin, consist- 

 ing of 7 groups, and designated achroo- 

 dextrin a, and so on by consecutive splitting and hydration until there occurs ultimately 

 a complete conversion into maltose. According to this theory the number of dextrins is 

 determined by the number of constituent molecules in the starch-molecule. There are 

 therefore 8 possible dextrins, 2 erythrodextrins and 6 achroodextrins, derivable from a 

 starch-molecule having the formula as above stated. As the action proceeds, the rotatory 

 power falls while the reducing power rises, until finally both powers correspond to the prop- 

 erties of maltose, as indicated in table 7. (See Brown and Morris, page 124.) 



The results recorded by Brown and Heron received sujjport in the investigations of 

 Squu-e (Jour. Soc. Chem. Industry, 1884, iii, 397). He states that his experiments confirm 



