324 MUCOUS MEMBRANE OF SMALL INTESTINE. [sect. 151. 



tubes, which extends as far as the openings of the glands. Here 

 the network, which must be considered as being continuous over 

 the whole stomach, is continued into a superficial network of 

 somewhat wider capillaries, 0'004'" to 0'Oo8'", which, in man, 

 surround the openings of the glands in the form of polygonal 

 meshes, o - 02'" to 0'04'" in diameter. This network is more developed 

 or more simple, according to the breadth of the mterglandular spaces, 

 and the occurrence of elevations upon them, but never appears to 

 consist of simple vascular rings. From this network the proportionally 

 wide veins always arise by several roots, which, at greater distances 

 from each other than the arteries, and without receiving any more 

 blood, traverse the layers of glands, and, at the outer surface of the 

 mucous membrane, pass into a wider network of the submucous 

 tissue, frequently at right angles, in part horizontally. From this 

 arrangement of the vessels, it becomes conceivable how, in the 

 stomach, an energetic secretion (by the deeper capillaries) and an 

 absorption (by the superficial wider networks) can take place at 

 one and the same time. 



The lymphatics of the stomach form, in the mucous membrane, a 

 superficial finer, and a deep coarser network, which are perceptible 

 only when injected. The numerous trunks passing out of the 

 mucous membrane are readily seen in the submucous tissue, in the 

 larger mammalia which have been killed during digestion, and 

 their union into larger trunks, and lastly, their penetration of the 

 muscular coat in the region of the curvature, are likewise distinctly 

 perceptible. The nerves of the stomach, from the vagus and 

 sympathetic, are readily traceable into the submucous tissue, and 

 may even be seen entering the muscular layer of the mucous mem- 

 brane, but are then entirely withdrawn from further investigation, 

 which is chiefly due to the circumstance, that in the interior of 

 the mucous membrane itself they no longer possess dark- 

 bordered fibres, but probably only pale ones of an embryonic 

 character. 



MUCOUS MEMBRANE OF THE SMALL INTESTINE. 



§ 151. The mucous membrane of the small intestine is thinner 

 than that of the stomach, but more complex, seeing that, besides 

 the tubular or Lieberkuhnian glands, it presents a great number of 

 permanent folds and villi, and contains in its tissue peculiar closed 



