DIFFERENCES IN PRODUCTS OF ACID AND ENZYMIC ACTION. 149 



Roux (Compt. rend., 1905, cxl, 1259) made comparative studies of the saccharifica- 

 tion of "artificial starches" (page 112) and ordinary starch-paste by malt extract at various 

 temperatures. After 4 hours digestion he found dextrin and maltose, but no glucose. 

 At 5G° the average apparent amount of maltose from the artificial starch was 97.9 per 

 cent, wliile from the ordinary paste it was 82.3 per cent. By fractionation the former 

 yielded 30.4 per cent of crystallized maltose and the latter 30.4 per cent. At 07° the 

 percentages of maltose from artificial and normal starches were 55.1 and 45, respectively. 

 At 80° the artificial starch was unaffected. The dextrins of artificial starch, unlike those 

 from ordinary starch, were almost completely soluble in alcohol. 



Fernbach and Wolff (Compt. rend., 1905, cxl, 1067) found that the energy of sacchari- 

 fication is influenced materially by the condition of the starch, whether in liquefied or in 

 paste form. Under the same condition of experiment the conversion products of liquefied 

 starch that had been obtained by heating to 140° to 145° were greater than those of boiled 

 starch as ordinarily prepared. They note that barley extract has a diastatic but not a 

 liquefying power. Starch liquefied by a minute amount of malt extract heated to 70° 

 behaved the same as starch liquefied at high temperatures; therefore, the addition of a 

 minute amount of malt extract (sufficient to cause liquefaction) to barley extract caused 

 very energetic saccharification. 



A modified form of dextrose, provisionally termed h-dextrose, was described by Roessing 

 (Chemiker Zeit., 1905, xxix, 867), and obtained by him from starch syrups or pure dextrose 

 that had been subjected under pressm'e to the action of dilute hydrochloric acid at tem- 

 peratures of 130° or higher. When sulphuric acid is used instead of hydrochloric, the tem- 

 perature might be raised to 160° without giving rise to this abnormal product. 



Maquenne and Roux (Compt. rend., 1906, cxlii, 142) recorded that if a starch-paste 

 and malt-extract mixture be nearly neutralized, a higher yield of maltose may be obtained. 

 Fernbach and Wolff (Compt. rend., 1906, cxlii, 1216) showed, however, that the increased 

 quantities can also be obtained without neutralization if a longer time of action be permitted. 

 Neutralization, they state, therefore merely increased the velocity of the reaction. They 

 record that any dextrin present, if separated, is saccharifiable, and that if there is present 

 any dextrin that is not convertible into dextrose, it must represent only an infinitesimal 

 fraction of the original starch. 



Croft Hill (Jour. Chem. Soc. Trans., 1898, lxxiii, 634), in experiments on reversible 

 hydrolysis, states that glucose can under proper conditions be synthetized into maltose 

 together with another sugar which he termed reverlose. Emmerling (Ber. d. d. chem. 

 Gesellsch., 1901, xxxiv, 600, 2206, 2207, 3810, 3811) showed that revertose is isomaltose. 

 This was confirmed by Armstrong (Proc. Roy. Soc, 1905, lxxvi, B., 592; The Simple 

 Carbohydrates and Glucosides, 1910). 



Emulsin, an enzyme that forms isomaltose, was found in yeast by Henry and Auld 

 (Proc. Roy. Soc, 1905, lxxvi, B, 568). Since yeast also contains maltase, which forms 

 maltose, the occurrence of both isomaltose and maltose can be accounted for by the inde- 

 pendent actions of the two enzymes, and not, according to Lintner and Diill, to the con- 

 version of isomaltose into maltose (page 144). In fact, yeast extract may contain at least 

 five diastatic enzymes, and emulsin at least three. 



DIFFERENCES IN THE PRODUCTS OF ACID AND ENZYMIC ACTION. 

 The striking analogy that exists between the processes and products of enzymic and 

 acid activity has not infrequently led to the assumption of a closer likeness than really 

 exists. It is assumed that both cause a degi'adation of the starch-molecule, and of the 

 intermediate products of saccharification, by successive stages of hydrolysis, and that 

 the stages as well as the intermediate and final products are essentially the same. But 

 there are abundant reasons for believing tliat there may not only be certain specific differ- 



