ISOMALTOSE, MALTOSE, GLUCOSE, SACCHAROSE, ETC. 139 



In an investigation of the products of activity of salivary and pancreatic enzymes in 

 the digestion of glycogen, Seegen (Centralbl. f. nied. Wissensch, 1870, xiv, 849) found 

 that even though the glycogen was completely digested there was formed a much smaller 

 amount of glucose than should be expected, only from 34 to 41 per cent of the calculated 

 amount in the case of saliva, and from 45 to 48 per cent in case of the pancreatic extract; 

 and he believes that some other kind of sugar is produced, or some other form of decom- 

 position product. 



Nasse (Ai-chiv f. ges. Physiologie, 1877, xiv, 473) confirmed Seegen's work and ex- 

 tended the investigations to starch. Nasse digested boiled arrowToot starch with filtered 

 human saliva on a water bath at 40°, varying the quantity of starch and the period of 

 digestion. In most cases the reducing power of the product amounted to only 48 per cent 

 of that called for. Even when 0.3 gram of starch in 20 c.c. of water and 15 to 20 c.c. 

 of saliva were digested from 6 to 7 hours, the reducing power was below 45 per cent of 

 what should be expected. He holds that animal diastatic ferments do not convert 

 starch into glucose, but into a form of sugar which he names amylum piyalose, wliich 

 when boiled with dilute sulphuric acid has its reducing power doubled. He also found 

 achroodextrin. In experiments with glycogen he determined the presence of both ptyalose 

 and acliroodextrin. 



Musculus and Gruber (Zeit. f. physiolog. Chemie, 1878, ii, 177) record both maltose 

 and dextrose. The former, ha\ang the formula CjoHooOxi, a rotatory power of (a) = +150°, 

 and a reducing power of 66, is believed by them to be formed from aclu-oodextrin and to 

 be convertible into glucose, each molecule being transformed by hydrolysis and cleavage 

 into 2 molecules of glucose according to the following: Ci2H220ii+H20 = 2(C6Hi206), 

 glucose having a rotatory power of (a) = +56 and a reducing power of 100. 



Nasse's assertion that a special form of sugar, and not glucose, results from the salivary 

 digestion of starch was shown to be erroneous by Musculus and von Mering (Zeit. f. physi- 

 olog. Chemie, 1878, ii, 403), who ascertained that the conversion of starch by saliva is 

 analogous to that by diastase, giving rise to achroodextrin, maltose, and glucose. After 

 repeated experinients they determined that under ordinary circumstances the quantities 

 of maltose and glucose formed by the action of saliva or diastase are 70 and 1 per cent, 

 respectively, of the original quantity of starch. 



Brown and Heron (Ann. d. Chem. u Pharm., 1879, cxcix, 241) using malt-extract 

 recorded the production of maltose, and state that the results of their experiments indicate 

 that even by the continued action on starch no glucose is formed, and that maltose is 

 the end product, undergoing no fiu-ther change. Pancreatic extract gave rise to both 

 maltose and glucose. The contradictory results of Musculus and von Mering on the one 

 hand by diastase, and of Brown and Heron on the other, as regards the formation of glucose 

 by diastase, were discussed by von Mering (Zeit. f. physiolog. Chemie, 1881, v, 185), who 

 attempted an explanation of the disagreement. Von Mering treated potato starch-i)aste 

 with diastase for 4 hom-s at 60° to 70°, and then for 20 hours at room-temperature, and 

 found by ordinary fractional precipitation of an alcoholic solution with ether that glucose 

 was present. The prolonged action of diastase increased the amounts of both glucose 

 and strongly reducing dextrins. Shorter action produced maltose, but no glucose. Maltose 

 remained unchanged after 2 hours' treatment with diastase at 60°, but after 24 hours the 

 reducing power was increased and the rotatory power decreased, indicating glucose forma- 

 tion. Putrefaction, watery yeast-solution, and emulsin did not convert maltose into 

 glucose; but jjy the prolonged action of saliva or pancreatic extract both maltose and 

 glucose wore formed, the pancreatic extract being energetic in the conversion of maltose 

 into glucose. He states that diastase and saliva will convert starch-paste into 2 dextrins, 

 one of which is broken down into maltose and a secondary glucose, while the other remains 

 unchanged by the same ferments. 



