398 CHEMISTRY OF THE DIGESTIVE PROCESSES. 



on starch, 1 but has a remarkable power in converting maltose into 

 grape-sugar. Brown and Heron surmised from this that maltose 

 would be found to be a non-assimilable substance ; unknown to them, 

 Bimmermann had already shown this to be the case, and many subse- 

 quent observers have confirmed the result. 



Digestion of cane-sugar. Cane-sugar resembles maltose in not 

 being directly assimilable from the blood ; after intravenous injection it 

 is excreted by the kidneys. In the course of digestion it is either com- 

 pletely inverted while in the alimentary canal, or may in part be so 

 changed in its passage through the absorbing cells of the mucous 

 membrane. 



Some cane-sugar is inverted in the stomach, probably by the action 

 of the hydrochloric acid there present. 2 Lehmann 3 repeatedly found, in 

 the stomach and duodenum of rabbits ied on beetroot, invert-sugar only. 

 Seegen found that, after feeding dogs on cane-sugar, the stomach always 

 contained a small amount of a reducing sugar along with a great deal of 

 unchanged cane-sugar ; and that the small intestine contained no sugar. 

 He argues from this, that all the cane-sugar is inverted in the stomach, 

 the invert-sugar being there absorbed as fast as it is produced. 

 It is probable, however, from the work of other observers, that a con- 

 siderable part of the inversion takes place in the small intestine by the 

 action of the intestinal juice, and it may be also by the direct action 

 of the cells of the intestinal mucous membrane. 



Watery infusions of the mucous membrane from any part of the 

 small intestine are capable of inverting cane-sugar, 4 and the same 

 power is possessed by the intestinal contents in animals which have 

 been killed during active digestion. 5 The intestinal juice obtained by 

 Vella 6 from fistulae almost instantly inverted cane-sugar, and a strong 

 inverting action of pure succus entericus has been observed by many 

 others. 



The inversion of the saccharoses by the intestinal juice is brought 

 about by enzymic action, but very little is known of the enzyme 

 or enzymes involved. It was supposed by Hoppe-Seyler and Thier- 

 f elder 7 that the inversion might be due to bacterial action or to 

 inverting enzymes taken in with the carbohydrate food, but the former 



1 A diastatic action on starch was found by Schiff, Jahresb. u. d. Fortschr. d. ges. Med., 

 Erlangen, 1867, Bd. i. S. 155 ; Eichhorst, Jahresb. u. d. Fortschr. d. Thier-Chem., 

 Wiesbaden, 1871, Bd. i. S. 198 ; Paschutin, ibid., S. 304 ; Ewald, Virchow's Archiv, 1879, 

 Bd. Ixxv. S. 409 ; Garland and Masloff, Untersuch. a. d. physiol. Inst. d. Univ. Heidelberg, 

 1878, Bd. ii. S. 290 ; Brown and Heron, loc. cit. ; Dana, Med. News, Phila., 1882, vol. xli. 

 p. 59. ; Hamburger, Arch. f. d. cjes. PhysioL, Bonn, 1895, Bd. Ix. S. 560; Mendel, ibid., 

 1896, Bd. Ixiii. S. 425. On the other hand, its existence is denied by Thiry and by Leube, 

 Jahresb. u. d. Fortschr. d. ges. Med., Erlangen, 1868, Bd. i. S. 97. It must be remembered 

 that the diastatic action is admittedly a slight one by most of those observers who confirm 

 it, and that most organs and tissues possess a slight diastatic action, so that it is difficult to 

 be certain that the intestinal mucous membrane specifically secretes a diastatic ferment. 



2 It is certain, from purely chemical experiments, that the acid is capable of producing such 

 an effect, and no inverting enzyme has ever been shown to exist in the gastric secretion. 



3 "Lehrbuch der physiol. Chem.," Aufl. 2. Bd. iii. S. 255; v. Becker, Ztechr. f. 

 unssensch. Zoologle, Bd. v. S. 123 ; J. Seegen, Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xl. 

 S. 41. 



4 Paschutin, Arch. f. Anat. u. Physiol, Leipzig. 1871, S. 306. 



5 Claude Bernard. "Le9ous sur la diabete et la glycogenese auimale," Paris, 1877, 

 257-261. 



6 Untcrsuch. z. Naturl. d. Mensch. u. d. Thiere, 1889, Bd. xiii. S. 62 ; see also 

 Bastianelli, ibid., 1886, Bd. xiv. S. 146. 



7 "Handbuch der. path. u. physiol. chem. Analyse," 1893, Aufl. 6, S. 298. See also 

 Pautz and Yogel, Ztschr. /. BioL, Miinchen, 1895, Bd. xxxii. S. 304. 



