THE INTESTINAL JUICE, 



327 



and a single layer of cylindrical protoplasmic cells, between which goblet-cells 

 also occur, in small number in the small, and in large number in the large intes- 

 tine. The glands in the small intestine yield a watery secretion principally; 

 those of the large intestine, from their numerous goblet-cells, ropy mucus. Both 

 kinds of gland-cells multiply by mitosis, and the new products move from situ- 

 ations where active division is going on to places where the production is less 

 active. The mucus in the goblet-cells encloses usually a single central body. 



The secretion of Lieberkiihn's glands is, from the duodenum down- 

 ward, the chief source of the intestinal juice. 



The intestinal juice is obtained, 

 by Thiry's method, in the following 

 manner: From a loop of the in- 

 testine of a dog, withdrawn from 

 the abdomen, a piece of the length 

 of a hand is so divided by two inci- 

 sions that only the continuity of the 

 intestinal canal is severed but not 

 the mesentery. Then one end of this 

 piece is ligated; the other, left open, 

 is sutured in the abdominal wound, 

 after the ends of the intestine, be- 

 tween which the piece has been re- 

 moved, have been carefully united 

 by suture. Vella permits both ends 

 of this horseshoe-shaped portion of 

 intestine to open on the abdominal 

 wall. In this way, after the opera- 

 tion has been completed, the animal 

 can continue to live with its but 

 slightly abbreviated intestine. The 

 intestinal fistula, with a free exter- 

 nal opening, yields, however, an in- 

 testinal juice that is not contamin- 

 ated by any other digestive secretion. 



The intestinal juice derived 

 from such a fistula flows spon- 

 taneously in very small amount ; 

 during digestion it is largely 

 increased. Mechanical, chemi- 

 cal and electrical stimulation 

 increase the secretion, especi- 

 ally of mucus, with reddening 

 of the mucous membrane, so 

 that 100 square centimeters 

 yield from 13 to 18 grams of 

 juice in an hour. The adminis- 

 tration of pilocarpin also in- 

 creases the secretion. The juice 

 is light yellow in color, opal- 

 escent, watery, strongly alkaline, 

 effervescing on addition of acids, and has a specific gravity of 1010. It 

 contains, in human beings, proteid (0.80 per cent.), ferments, mucin, 

 especially in the large intestine (0.73 per cent.), and salts (0.88 per 

 cent.), of which 0.34 per cent, is soda and 0.5 per cent, sodium chlorid. 



The amount of intestinal juice secreted is least with the presence of dissolved 

 grape-sugar in the intestines, greater with the presence of cane-sugar, and still 

 greater with the presence of starch and peptone. It increases in the second hour 

 of digestion. 



G. 



FIG. 120. Longitudinal Section through the Small 

 Intestine of a Dog: B, connective-tissue layer; 

 Z, intestinal villi covered with cylindrical epithe- 

 lium; L, Lieberkiihn's glands; Mm, muscularis 

 mucoss; G, crowded lymph-follicles; Me, circular 

 muscular layer; Ml, longitudinal muscular layer. 



