THE ESSENTIALS OF HISTOLOGY. 



intercellular channels, which are bridged across by numerous fibres 

 passing from cell to cell, and giving the cells, when separated, the 

 appearance of being beset with short spines (prickle-cells of Max 

 Schultze). 



The deeper cells multiply by division, the nuclei first dividing in the 

 manner just described. The newly formed cells tend as they enlarge to 

 push those external to them nearer to the surface, from which they are 

 eventually thrown off. As they approach the surface they become hard 

 and horny, and in the case of the epidermis lose entirely their cellular 

 appearance, which can, however, be in a measure restored by the action 

 of potash ( 2). The cast-off superficial cells of the stratified epithelium 

 of the mouth, which are seen in abundance in the saliva ( 1), are less 

 altered, and the remains of a nucleus is still visible in them (fig. 26). 



Simple scaly or pavement epithelium 

 is found in the saccules of the lungs, in 

 those of the mammary gland when in- 

 active, in the kidney (in the tubes of 

 ftt**'j/A x ""'""' a <"V ^Y Henle), and also lining the cavities of 

 jv/^-^^^^' serous membranes (fig. 27), and the 



^-^^ heart, blood-vessels, and lymphatics. 



FIG. 2(3. EPITHELIUM-SCALES FKOM ___. . . 



THE INSIDE OF THE MOUTH. (Mag- When occurring on internal surfaces, 

 nified 200 diameters.) such as those of the serous membranes, 



blood-vessels, and lymphatics, it is often spoken of as endothelium. 



FIG. 27. PAVEMENT EPITHELIUM OR ENDOTHELIUM OF A SEROUS 

 MEMBRANE. NITRATE OF SILVER PREPARATION. 



