228 S. SAGUCHI 



17. Efferent ducts of the rat and mouse. The epithelium con- 

 sists of ciHated cells and cells with brush borders. The ciliated 

 cells (figs. 84-88) taper gradually to their proximal extremity. 

 Their nuclei are large and take a higher position than those of 

 neighboring cells, as already noticed by Lenhossek (1898). The 

 uppermost portion of the cell-body generally is of a dense char- 

 acter, and basal corpuscles, rod-like, diplosome- or dumb-bell- 

 shaped, are arranged here in parallel rows. Any well-defined 

 cuticular border, such as seen in other places, is nob discernible 

 here. There are centrosomes in the transparent zone. The 

 chondriocontes are mainly collected below the transparent zone, 

 without entering into it. The basal corpuscles, viewed in tan- 

 gential sections, are not scattered ii-regularly, but are arranged 

 in linear series, parallel to one another and at right angles to the 

 larger diameter of the cell-border. There is always a single 

 nucleus. 



18. The trachea of the rat and mouse. The ciliated cells of the 

 trachea of these forms (figs. 91-95) are bordered with a distinct 

 cuticle through which the cilia pass downwards to connect with 

 basal corpuscles. These are small spherical granules situated 

 under the cuticle; in a surface view their linear arrangement is 

 conspicuous (fig. 95). The chondriocontes never enter into the 

 transparent zone. The cells are often provided with two nuclei, 

 the centrosome is readily discernible. 



B. GENERAL CONSIDERATIONS 



a. The 7nanner of implantation of the cilia 



Ciliated cells are either columnar, or cubical, or, in rare cases, 

 flattened in shape, and, although they participate in the forma- 

 tion of the simple or stratified epithelium, it can hardly be said 

 that there is any epithelium which consists of ciHated cells only, 

 other kinds of cells, such as non-ciliated columnar or glandular 

 cells almost invariably entering into its composition. And while 

 the cihated cells, on the one hand, are partly eliminated after 

 degeneration, partly converted into columnar or glandular cells, 

 the columnar epithelial cells, on the other hand, become trans- 



