EPITHELIUM OF THE LAKYNX. 39 



and somewhat flattened cells, forming a stratum Malpighii, 

 before they become flattened into the superficial corneal 

 lamina. Towards the cushion of the epiglottis the cylindrical 

 basal cells become elongated, whilst the superjacent cell layers 

 become correspondingly attenuated, and ultimately, with the 

 persistence of the now elongated basal cells, entirely disappear ; 

 these last then acquiring cilia having a length of 0'005 of a 

 millimeter, and becoming converted into ciliated cells. Between 

 their attached extremities are numerous round or oval cells, 

 and the new epithelial investment may attain a thickness of 

 0'15 of a millimeter, or more. 



The transition of the epithelial formation of the anterior to 

 that of the posterior surface of the epiglottis occurs in such a 

 manner that the tesselated epithelium of the anterior surface 



Fig. 124. 



Fig. 124. Epithelium of the posterior surface of the epiglottis, with a 

 bulb-like structure, a. Transverse section of the central canal. 



invests the border of the cartilage, and then becomes suddenly 

 attenuated. In the newly born child the entire posterior 

 surface of the epiglottis is covered by a layer of ciliated epi- 

 thelium amounting to O08 O01 of a millimeter in thickness. 



At about the second fourth of the posterior surface of the 

 epiglottis, where the epithelium ordinarily presents its transi- 

 tion into the ciliated form, clavate, or in some instances 

 pyramidal, structures are found, the apices of which approxi- 

 mate the horny layer, and give off a fine canal that reaches the 

 surface either by pursuing a straight course or after making a 



