J-J..U 



testin 



E. SMALL INTESTINE, BY E. VERSON. 573 



of a millimeter, but may amount to only one half of this, or 

 even less. 



EPITHELIUM. The free surface of the mucous membrane is 

 covered with columnar cells, usually arranged in a single layer, 

 but presenting at some points, as for instance over Peyer's 

 patches, rounded cells between their attached extremities. 



The epithelial cells of the small intestine are sometimes 

 columnar, sometimes conical, and in the latter case are attached 

 by their apices, and present their bases to the cavity of the 

 intestine. They undergo considerable modification from the 

 action of reagents, becoming clavate, irregularly swollen, drawn 

 out into long processes, etc. 



The free border of the uninjured epithelial cells of the in- 

 .e presents a broad seam or hem, which under favourable 

 circumstances (with good microscopes) exhibits a fine striation 

 running parallel to the long axis of the cell. If the cells have 

 already undergone change, the striae become irregular, some of 

 the lines projecting beyond the others others ceasing to pre- 

 serve their parallel arrangement. It has been a subject of 

 discussion whether these striae are the expression of fine canali- 

 culi traversing the hem perpendicularly,* or whether they 

 represent small rods of which it is composed.-)- This con- 

 troversy has to a certain extent lost its importance, as neither 

 the canaliculi nor the rods furnish any satisfactory explanation 

 of the mode in which the absorption of fat molecules is 

 effected. 



Besides the ordinary columnar cells of the intestine, and con- 

 stituting a very remarkable and frequent appearance, are cup, 

 bell, or goblet-shaped structures, the open mouths of which 

 are directed towards the cavity of the intestine, and which 

 contain at their base a mass of protoplasm of variable size 

 with or without a nucleus. Brettauer and SteinaehJ originally 



* Funke, Zeitschrift far wissenschaftliche Zoologie, Band vi. Kolliker, 

 Wiirzburger Verhandlungen, Band vi. 



+ Brettauer and Steinach, Sitzungsberichte der Kaiser. Akademie der Wis- 

 senschaften, 1857. 



I Loc. cit. 



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