HISTOLOGICAL DEMONSTRATIONS. 71 



motion and the structure of ciliated epithelium may be studied 

 in cells obtained from the frog's pharynx, or from the trachea 

 of rabbit or cat. If the latter animals be employed, they 

 should be killed by a blow on the head, and not by ether 

 or chloroform, otherwise the cilia will be paralysed. The 

 cells may be examined fresh, and then stained with 

 magenta to bring out the nucleus and the granular pro- 

 toplasm ; or they may be placed for twenty-four hours 

 in i per cent osmic acid, and then examined. The cells 

 may be rendered easily separable by a twenty-four hours' 

 immersion in dilute alcohol ( 284), and then scraping 

 the epithelial surface. Magenta then stains the cells very 

 readily. 



93. Scrape off some cells from the tracheal mucous mem- 

 brane of a cat, hardened in osmic acid as above mentioned ; 

 add glycerine ; tease with needles ; cover, and examine. 

 Observe the nucleus and nucleolus, the granular protoplasm 

 sometimes with vacuoles, the cilia and the clear band under 

 them. The clear band, however, may not now appear 

 homogeneous, as in the fresh condition, but striated verti- 

 cally. 



With a power of about 1000 diam., it may be seen that the striae 

 are apparently continuations of the cilia into the granular protoplasm. 

 They may be seen passing a very short way below the clear band ; but 

 we have never seen them even after various methods . of staining 

 passing to the nucleus, as has been alleged. 



A preparation of ciliated epithelium for preservation 

 will be obtained in the section of hardened trachea to be 

 afterwards examined ( 115). The cells hardened in osmic 

 acid may be preserved in potassium acetate (351) or 

 Farrants' solution. 



94. Columnar Epithelium and "Chalice Cells" 

 (H.) Remove a portion of the wall of the large intestine 

 from a cat recently killed. Wash the mucous membrane 

 with j per cent salt solution. Scrape off the epithelium 

 and diffuse it with the point of a needle in a drop of 

 magenta solution. Columnar cells and chalice cells will be 

 found. 



