ELEMENTARY TISSUES. 



epithelium (figs. 4 and 5), which extends from the cardiac 

 orifice of the stomach along the whole of the digestive 

 canal to the anus, and lines the principal gland-ducts which 



Fig. 4-* 



open upon the mucous surface of this tract, sometimes 

 throughout their whole extent (a, fig. 3), but in some cases 

 only at the part nearest to the orifice (6 and c] . It is also 



Fig. 5-t 



c . 



found in the gall-bladder and in the greater portion of the 

 urethra, and in some other parts, as the duct of the parotid 

 gland and of the testicle. It is composed of oblong cells 

 closely packed, and placed perpendicularly to the surface 

 they cover, their deeper or attached extremities being most 



* Fig. 4. Cylindrical epithelium from intestinal villus of a rabbit ; 

 magnified 300 diameters (from Kb'lliker). 



f Fig. 5. Cylinders of the intestinal epithelium (after Henle) : 

 B. from the jejunum ; c. cylinders of the intestinal epithelium as 

 seen when looking on their free extremities ; D. ditto, as seen on a 

 transverse section of a villus. 



