THE VISCERA. 209 



commencement of the large intestine (csRCiim), and is separated 

 from it by a valve (valvula Bauhini] [^Ileo-cxcal and Ileo-colic]. 

 We divide it into : Duodenum [equal to the breadth of twelve 

 fingers] and mesenteric intestine (that is, Jejunum and Ileum as- 

 sociated together). The small intestine is distinguished by its 

 greater length (fourfold), its narrowness, and its structure, from 

 the large. 



The mucous membrane of the small intestine is paler than that of the sto- 

 mach, and presents on its internal free surface, valvula conniventes, villi, arid 

 glands. 



1. Valvmla. conniventes Kerkringii consist of folds of the mucous membrane, 

 inside of which loose uniting tissue, vessels and nerves only are found. They 

 are placed vertically to the axis of the intestine, form one-half, two-thirds, or 

 three-fourths of a circle, are broadest in the centre (two to three lines), and 

 lie more or less parallel, close to, or in, the empty intestine, in an imbricated 

 manner over one another. They commence one to two inches below the 

 Pylorus, increase in number to about two-fifths of the mesenteric intestines, 

 and then decrease, until at the termination of the last they are altogether 

 wanting. The superficies of the intestine is said to be increased by their 

 presence about two, three, or even six fold. 



2. Villi (papilla) cover the entire small intestine, the valv. conniventes as 

 well as the depressions between them. Number: undetermined; 4000 upon 

 one square inch. Length =0'2 to 0*8 of a line. Shape: foliaceous (in man), 

 filiform (in the dog, cat) ; different in other animals. Structure: each villus 

 consists of uniting tissue, like the papillae of the corium and tongue, extending 

 into a sheath of Epithelium (Henle) ; but containing, instead of nervous plex- 

 uses, a minute ramification from the lymphatic rete, surrounded by capillary 

 vessels (according to Lieberkiihn a cavity, ampulla, at the basis, and an open- 

 ing at the point, from which the Chyle- vessels proceed). The absorption of 

 the Chyle in all probability takes place without an opening in the villus. 



3. Glands: a. Gland, solitaries, simple mucous follicles, are dispersed 

 through the whole of the small intestine ; they are the size of a millet seed, 

 push forward the mucous membrane beset with papillae, are hollow, (gene- 

 rally), closed, but surrounded by a coronet of obliquely placed open tubules 

 (gland. Lieberkiihniana;?), which are said to communicate with their cavity 

 (Krause). They contain a clear, white, or granular substance, and are some- 

 times open, in a congested condition, appearing then as inversions of the Mu- 

 cosa (Henle). 



b. Gland. Peyeriana are distinguished from the solitary, merely by their 

 occurring in masses (gl. agminatce), and possessing thinner walls which, like 

 those of the latter, are also structureless. These accumulations of glands are 

 elliptical, lying in the longitudinal axis (of the small intestines) on the convex 

 border, opposite to the attachment of the mesentery ; particularly abundant at 

 the termination of the Ileum, decreasing in number towards the Duodenum. 

 They are also surrounded by a coronet of tubules, and are sometimes open. 



c. Gland. Brunneriance (pancreas secnndarium) are flat, oval, lenticular, 

 racemose glands, divided into lobules (gl. acinorum composite), which project 

 more outwardly than towards the mucous membrane. Disseminated in 

 masses they are found in the pars horizont. super, of the duodenum, but only 

 singly. They open with wide mouths. 



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