CHAP. XXV.] THE INTESTINAL GLANDS. 231 



free extremities, and the peculiar vesicular structure at the apices 

 of the villi is compressed, or otherwise concealed from view or 

 altered in character. (Fig. 160). Lastly the epithelium seems 

 to adhere much less closely to the villi during chylification than 

 during fasting ; and the epithelial particles themselves appear to 

 undergo some change during this process. This latter change is 

 represented in the annexed cut (fig. 163) ; the epithelial particles 

 appear larger, their contents more distinct, and consisting of minute 

 fatty grains as well as of some small globules. 



Of the Glands of the Intestine. These are, in addition to the 

 Lieberkiihn's tubes or follicles already described, and which are 

 themselves secreting organs : 1. Brunner's or the duodenal glands ; 

 2. The solitary glands ; 3. Peyer's glands, or glandulce aggregates. 



Brunner's glands belong properly to the duodenum. They were 

 discovered and described 

 by J. C. Brunn in 1686. 

 We find them in the 

 submucous areolar tis- 

 sue, disposed as a more 

 or less thick layer of 

 whitish grains, immedi- 

 ately beneath the mucous 

 membrane. They may be 



-, , , Vertical section of the mucous membrane of the duodenum 



Compared tO the Clement- in the horse, slightly magnified, shewing, v, villi, 6, c, mucous 



,. membrane and submucous tissue, g. Brunner's glands cut 



ary grains OI a Salivary vertically, and a little spread out, shewing their lobulated 



i-i T structure. 



gland spread out on an 



expanded surface, instead of being collected into a mass. Near 

 the pylorus they are most numerous, and most closely set and 

 largest ; towards the termination of the duodenum they become 

 much fewer, smaller, and scattered ; and nothing resembling them 

 is found in any other portion of the intestine. They are much 

 more developed in the Herbivora than the Carnivora ; in man they 

 are large and numerous, generally speaking, but exhibit a good 

 deal of variety in different subjects, and in the very old they 

 appear to have wasted and shrunk. 



In point of structure, Brunner's glands resemble precisely the 

 pancreas. Their ultimate elements are bunches of vesicles which 

 contain globular epithelium, and from which ducts arise which 

 coalesce and form larger ducts, through which the secretion is 

 poured into the duodenum. The exact relation of these ducts to 

 the tubes of Lieberkiihn is not known. 



Brunner's glands, no doubt, secrete a fluid similar, perhaps, in 



