180 



DIGESTION. 



intestine. It probably exists, more or less fully developed, in all the 

 organs taking part in the digestive process. 



The Intestinal Juice and Digestion in the Intestine. 

 The secretory apparatus of the small intestine consists of two sets of 

 glandular organs, namely, first, Brunner's glands, which are compound 

 or lobulated, and confined to the upper part of the duodenum, forming 

 a sort of collar round the intestine for a distance of several centimetres 

 from the pylorus ; and, secondly, the follicles of Lieberkuhn, which are 

 simple tubular glandules, occupying the substance of the mucous mem- 

 brane for the whole length of the small intestine. ^ 



Fig. 47. 



LONOITTJDINALSKCTION OF WALL OF DUODENUM IN THE DOG; showing the sub- 

 mucous layer of Brunner's Glands, a. Mucous membrane, b. Layer of submucous connective 

 tissue, in which the glands are situated, c. Muscular coat. d. Peritoneal coat. e. Brunner's 

 glands, with their ducts opening upon the free surface of the mucous membrane. (Bernard.) 



Brunner's glands, or the duodenal glandules as they are sometimes 

 called, are situated in the submucous layer of connective tissue in this 

 part of the intestine. They are spherical, or, when thickly set, irregu- 

 larly flattened or polygonal in shape from mutual pressure, and from ^ 

 to 1 millimetre in diameter. 



Fig. 48. 



Fig. 49. 



Entire BRUNNER'S GLAND, from human intestine. 

 (Frey.) 



Portion of one of BRUNNER'S 

 GLANDS, from human intestine. 



In their structure, the glands are similar to the lobulated glandules 

 of the mouth, being composed of rounded follicles clustered about a 

 central branching excretory duct. Each follicle is about T V of a milli- 

 metre in diameter, and consists of a delicate membranous wall, lined 



