THE INTESTINES. 99 



§154. 



Glands of the small intestine, — The small intestine contains 

 only two kinds of true glands; viz., 1. tubular glands, which are 

 disposed over the whole mucous membrane; and 2, racemose 

 glands, in the submucous tissue of the duodenum. 



The racemose glands, or as they are more commonly named, 

 after their discoverer, Brunner f s glands, form, at the com- 

 mencement of the duodenum, upon the outer side of the mu- 

 cous membrane, a continuous layer, which is best developed 

 and thickest, close to the pylorus, where it constitutes a con- 

 siderable glandular ring and extends about as far as the aper- 

 ture of the biliary ducts. If the two layers of the muscular 

 tissue be dissected off a stretched or distended duodenum, 

 the glands may readily be recognised as yellowish, flattened 

 bodies of ^ — 1|'" (on the average \ — J'"), with their angles 

 rounded off, which, enclosed within a little connective tissue, 

 lie close to the mucous membrane and send short excretory 

 ducts into it. In their minute structure, Brunner's glands, 

 the terminal vesicles of which measure 003 — 0-06, even 0*08"', 

 agree perfectly with the racemose glands of the oral cavity 

 and oesophagus. Their secretion is an alkaline mucus, in which 

 no formed elements are contained, having no digestive action 

 upon coagulated protein compounds and probably merely sub- 

 servient to mechanical ends. 



The tubular, or Lieberkuhnian glands {cryptce mucosae) , 

 are distributed over the whole small intestine, including the 

 duodenum, as innumerable, straight, narrow cseca, which 

 occupy the entire thickness of the mucous membrane and are 

 frequently slightly enlarged at their extremities, though hardly 

 ever dichotomously divided. The best idea of their number i3 

 obtained by viewing the mucous membrane either from above 

 or in vertical section, under a low power. In the latter case, 

 we see the caeca standing close together, almost like palisades 



that in which the ingesta enter an Actinophrys ; one can as readily comprehend 

 the existence of a selective power in the former as in the latter case. That some 

 such faculty exists would seem to he indicated hy the fact stated by Briich, that the 

 Lieberkuhnian and Peyerian glands take no share in fatty absorption; though, on 

 the other hand, it must be remembered that Kolliker found the eggs of Eutozoa in 

 the villi of rabbits (' Mikr. Anat.,' B. II, 2, 173).— Eds.] 



