232 



DIGESTION. 



[CHAP. xxv. 



Fig. 165. 



Fig. 166. 



nature to the pancreatic fluid, which exercises an influence on 

 that portion of the digestive process which takes place in the 

 duodenum! Their restriction to the upper portion of the intestine, 

 and their mode of arrangement in an expanded form beneath the 

 mucous membrane, establish for them an analogy with the buccal 

 glands, which are similarly disposed beneath the mucous membrane 

 of the mouth, and which bear to the salivary glands the same rela- 

 tion as the duodenal glands do to the pancreas. 



These glands, restricted as they 

 are to the upper portion of the 

 intestine, give a character to it of 

 a physiological kind, and there- 

 fore more definite than any ex- 

 ternal boundary. Accordingly, 

 while the duodenum may pro- 

 perly give its name to these glands, 

 so the presence and extent of 



A solitary gland from the small intestine of the .I/L 1.111 j_i . m 



human subject magnified. After Boehro. them should denote that portion 



of intestine which may be called 

 duodenum, and define its limits. 



The solitary glands are found 

 in all parts of the intestine, but 

 are most numerous in the jeju- 

 num, in the ccecum, in the ver- 

 miform appendix, and in the rest 

 of the large intestine. When 

 filled with their secretion they are 

 like small grains, about as large 

 as those of mustard-seed, placed 

 beneath the mucous membrane in 

 the submucous tissue, which can- 

 iiot in those situations be inflated ; 

 they may be readily seen by 

 holding up the intestine against 

 the light. When empty and col- 

 lapsed they are not easily dis- 

 covered, and therefore are fre- 

 quently overlooked. 



One of these glands is a simple 

 vesicle, or sacculus, of mem- 

 brane, shaped like an India-rubber bottle, with a narrow ex- 

 tremity corresponding to the surface of the mucous membrane, 



A patch of Peyer's elands of the adult human 

 subject, from the lowest part of the ileuin. After 

 Boehm. 



