CILIATED EPITHELIUM. 



31 



these as cells in a state of proliferation. Chalice cells, unicellular 

 mucous glands, are numerous amongst the columnar cells. Some 

 are full of a transparent secretion (mucigen), others empty and 

 collapsed. The former are like footless wineglasses. Leucocytes 

 occur frequently betAveen the cells. 



Ciliated Epithelium. Trachea of a child. T.&. (p. 8, 

 s. 22 & 24, c. P., m. B.) (Z,) Find the inner layer. (H) The 

 free surface is covered with columnar ciliated epithelium, the 

 lower layers of cells are pear-shaped or rounded, and rest upon 

 a well denned basement surface. The epithelium is renewed by 

 the proliferation of the lowest cells. 



Isolated ciliated cells from the pharynx of the frog (p. 24 to 

 48 hours in 33 1XC alcohol, coloured by Picrocarmine (Ranvier) 

 m. Gl.) (H) Irregular \vedge-shaped nucleated cells, the free 

 ends of which are tufted Avith cilia implanted in a marginal zone. 

 Chalice cells, some full of granules (mucigen) stained yellow, 

 others empty, occur in considerable numbers. 



Ciliary action. 1 Open a mussel by cutting through the hinge, 

 Fig. 11, then pass the knife between the shells to sever the adductor A and 

 soft parts. The thick border 

 of the mantle lies within the 

 long side of the shell. It 

 retracts on being touched if 

 the mussel is alive. Lying 

 upon the mantle in a double 

 layer is the gill. Cut out a 

 small piece of the gill with 

 scissors, place it on acover- 

 glass in a drop of fluid 

 from the mussel, and separate the two layers. Invert the preparation 

 (hanging drop] upon a cell formed of three thicknesses of blotting paper, 

 cut so as to fit the slide, and with a central aperture inch in diameter, 

 and moisten with salt solution. Fig. 12. 



1 A scraping from the pharynx of the frog diffused in normal saline answers very well. 



FIG. 11. 



