328 THE INTESTINAL JUICE. 



Biedermann found the production of mucus in the goblet-cells of the intestine, 

 in the frog, to take place in such a manner that droplets of mucus first appear 

 in the cell-contents. These enlarge into vacuoles, which soon become confluent; 

 then the mucus escapes from these and is discharged from the cell. 



The digestive activity of the juice of the small intestine is still in 

 many respects unexplained. The juice has been found most active in 

 the dog, while it is more or less inactive in other animals. 



It possesses less diastatic activity than the saliva and the pancreatic 

 juice. It forms maltose, which rapidly passes over into dextrose. The 

 glands of the large intestine are said to be wanting in this property, 

 von Wittich has extracted the ferment by means of glycerin diluted 

 with water. 



The intestinal juice is capable of transforming maltose into grape- 

 sugar. It, therefore, continues the diastatic action of the saliva and 

 the pancreatic juice, which principally are active only up to the pro- 

 duction of maltose. 



According to Bourquelot, this action is due to intestinal bacteria, and not 

 to the intestinal juice as such, nor to the saliva, the gastric juice or the invertin. 

 The larger part of the maltose, however, seems to undergo absorption unchanged. 



No action upon proteids is recognizable, or, at least, only traces. 



The peptonizing properties described 

 are in part dependent upon putre- 

 factive processes. According to 

 earlier statements, fibrin is slowly 

 peptonized by trypsin and pepsin; 

 albumin, fresh casein, raw or cooked 

 meat and vegetable albumin less 

 readily. Gelatin is probably also 

 brought into solution by a special 



FIG. 121. Transverse Section through Lieber- ferment. 



kuhn's Glands: H, cavity of the glandular The intestinal JU1C6 is Capable of 



tubule; D, glandular epithelium; B, connec- . % . - . . ... 



tive tissue; G, blood-vessels. acting on tat, which it partially 



emulsifies in the presence of free acid. 



Whether the neutral fats are also decomposed, in small measure, has 

 not as yet been determined with certainty. 



The intestinal juice contains invertin, an unorganized ferment, which 

 decomposes disaccharids (cane-sugar, milk-sugar and maltose) into 

 monosaccharids (dextrose, levulose and galactose), with the taking up 

 of water and the production of heat : 



C 12 H 22 O n 4- H 2 = C 6 H 12 6 + C 6 H 12 6 



Cane-sugar + Water = Dextrose Levulose. 



Milk (casein) is coagulated. 



With regard to the ferments of the alimentary canal, Langley upholds the 

 view that they undergo destruction: the diastatic ferment of the saliva is de- 

 stroyed by the hydrochloric acid of the gastric juice ; pepsin and the rennet-ferment 

 succumb to the action of the alkaline salts of the pancreatic and intestinal juices 

 and the trypsin; the diastatic and peptic ferments of the pancreas are rendered 

 inert by the acid fermentation in the large intestine. Nevertheless some ferment 

 is absorbed and passes over into the urine. 



Of the influence of the nerves upon the secretion of the intestinal juice but 

 little has been ascertained with certainty. Stimulation or division of the pneumo- 

 gastric nerves is without apparent effect. On the other hand, destruction of the 

 nerve-filaments passing to the intestinal loops and accompanying the blood-ves- 

 sels is followed by distention of the intestinal canal with an abundance of watery 



