368 THE INTESTINAL JtJICE. 



hippuric acid) forms urea, as the urea is increased after the injection of glycin 

 (Horsford, Schultzen, Nencki). The fate of taurin is unknown. When large 

 quantities are introduced into the human stomach, it reappears in the urine, as 

 tauro-carbonic acid, along with a small quantity of unchanged taurin. When 

 injected subcutaneously into a rabbit, nearly all of it reappears in the urine. 



183. The Intestinal Juice, 



The human intestine is ten times longer than the length of the body, as 

 measured from the vertex to the anus. It is longer comparatively than that of 

 the omnivora (Henning). Its minimum length is 507, its maximum 1,149 centi- 

 metres; its capacity is relatively greater in children (Beneke). In childhood the 

 absorptive elements, in adults the secreto-chemical processes, appear to be most 

 active (Baginsky). 



The succus entericus is the digestive fluid secreted by the numerous 

 glands of the intestinal mucous membrane. The largest amount is 

 produced by Lieberkiihn's glands, while in the duodenum, there is 

 added the scanty secretion of the small compound tubular Brunner's 

 glands. 



Brunner's glands are small convoluted, branched, tubular glands, lying in 

 the sub-mucosa of the duodenum. Their fine ducts run inwards, pierce the 

 mucous membrane, and open at the bases of the villi, The acini are lined by 

 cylindrical cells, like those lining the pyloric glands. In fact, Brunner's glands 

 are structurally and anatomically identical with the pyloric glands of the stomach. 

 During hunger, the cells are turbid and small, while during digestion they are 

 large and clear. The glands receive nerve-fibres from Meissner's plexus (Drasch). 



I. The Secretion of Brunner's Glands. The granular contents of the 

 secretory cells of these glands, which occur singly in man, but form 

 a continuous layer in the duodenum of the sheep, besides albuminous 

 substances, consist of mucin and a ferment-substance of unknown consti- 

 tution. The watery extract of the glands causes: (1) Solution of 

 proteids at the temperature of the body (Krolow). (2) It also has a 

 diastatic (?) action. It does not appear to act upon fats. [Brown and 

 Heron have shown that the secretion of Brunner's glands, more actively 

 than any other glands of the intestines, converts maltose into glucose.] 



On account of the smallness of the objects, such experiments are only made 

 with great difficulty, and, therefore, there is a certain amount of uncertainty with 

 regard to the action of the secretion. 



Lieberkiihn's glands are simple tubular glands resembling the finger of a 

 glove [or a test tube], which lie closely packed, vertically near each other, in the 

 mucous membrane; they are most numerous in the large intestine, owing to the 

 absence of villi in this region. They consist of a structureless membrana propria 

 lined by a single layer of low cylindrical epithelium, between which numerous 

 goblet-cells occur, the goblet-cells being fewer in the small intestine and much 

 more numerous in the large (Fig. 146). The glands of the small intestine yield a 

 thin secretion, while those of the large intestine yield a large amount of sticky 

 mucus from their goblet-cells (Klose and Heidenhain). 



