PRODUCTS OF DIGESTION OF STARCH. 397 
(achrobdextrin). If, when this stage is reached, the solution is rapidly 
cooled and neutralised, a little maltose can be separated from accompany- 
ing dextrose, showing that maltose is here also formed, but is con- 
verted rapidly into grape-sugar. 
Although maltose is the chief sugar formed in the action (if both 
ptyalin and amylopsin upon starch, yel a trace of grape-sugar is also 
formed. 1 The quantity of grape-sugar formed is in both cases small, but 
is greater in the case of the pancreatic ferment. It has recently been 
discovered that in both salivary and pancreatic digestion, besides 
maltose and small quantities of grape-sugar, another sugar, isomaltose, 2 
is formed, in considerable quantity. The relative quantity of the three 
sugars varies with the quantity of ferment present, and the duration of 
the experiment. A weak ferment and short time of action favour the 
formation of isomaltose; by much ferment and prolonged action large 
quantities of maltose are produced, accompanied by traces of dextrose. 3 
It is stated that traces of an inverting ferment are present, both in the 
salivary and pancreatic glands, especially the latter; and it is possihle 
that the traces of dextrose formed may he due to the action of these on 
the maltose and isomaltose first formed. 
The action of the amylolytic enzymes on glycogen is precisely similar 
to their action on starch ; dextrin, maltose, and isomaltose being formed 
in very much the same proportions. 4 
The production of maltose by the diastatic ferments is not the end 
of the digestion of amyloses ; there is evidence that maltose never 
reaches the systemic circulation. If it be injected intravenously it is soon 
discoverable in the urine ; 5 this shows that in digestion it is inverted, 
either before it is absorbed, or after absorption and before reaching the 
systemic circulation. 
This further process of hydrolysis may be to some extent carried out, 
so far at least as concerns that portion of maltose arising from 
salivary digestion, by the hydrochloric acid of the gastric secretion, but it 
is mainly brought about by an inverting ferment, discovered by Brown 
and Heron in the mucous membrane of the small intestine, and also in 
the succus entericus. 6 
The succus entericus (as well as the intestinal mucous membrane and 
glycerin or water extracts of it) possesses only a feeble diastatic action 
1 Musculus and Gruber, Ztschr. f. physiol. Chem., Strassburg, 1878, Bd. ii. S. 177 ; 
Museulus and von Mering, ibid., 1878, Bd. ii. S. 403 ; von Mering, ibid., 1881, Bd. v. S. 
185 ; Brown and Heron, Ann. d. Chem., Leipzig, 1879, Bd. excix. S. 165 ; 1880. Bd. cciv. S. 
228 ; Proc. Boy. Soc. London, 1880, p. 393. 
2 Ktilz u. Vogel, Ztschr. f. Biol., Miinchen, 1894, Bd. xxxi. S. 108. The existence of 
isomaltose is, however, denied by Brown and Morris [Trans. Chem. Soc, London, 1895, vol. 
lxvii. p. 737), who state that it is a mixture of maltose and dcxtrins. 
3 Jour n. Physiol., Cambridge and London, vol. xv. ; Abelous, Compt. rend. Soc. de biol., 
Paris, 1891. 
4 Hensen, Verhandl. d. phys.-med. Gesellsch. zu Wurzburg, 1856, Bd. vii. S. 219 ; 
Virchoxcs Archil), 1857, Bd. xi. S. 395 ; Claude Bernard, Gaz. med. de Paris, 1857, No. 13 ; 
J. Seegen, Centralbl. f. d. med. Wissensch., Berlin, 1876, S. 849 ; Arch. f. d. gcs. Physiol., 
Bonn, 1879, Bd. xix. S. 106; Kiilz u. Vogel, Ztschr./. Biol., Miinchen, 1894, Bd. xxxi. 
S. 108. 
5 Bimmermann, Arch. f. d. gcs. Physiol., Bonn, 1879, Bd. xx. S. 201 ; Philips, 
Jahresb. ii. d. Fortschr. d. Thicr-Chem., Wiesbaden. 1881, Bd. xi. S. 60 ; Dastre et Bour- 
quelot, Compt. rend. Acad. d. sc, Paris, 1884, tome xcviii. p. 1604'; Bourquelot, Journ. de 
Vanat. et physio/., etc., Paris, 1886, tome xxii. p. 161. 
6 Brown and Heron, Proc. Boy. Soc. London, 1880, p. 393 ; Ann. d. Chem., Leipzig, 
1880, Bd. cciv. S. 228 ; Vella, Untersuch. z. Natarl. d. Mcnsch. u. d. Thicre, 1881, Bd. 
xiii. S. 40; Bourquelot, Compt. rend. Acad. d. sc, Paris, 1883, tome xevii. p. 1000. 
