EXPLANATION OF THE PLATES. 



PLATE XXVI. 



STRUCTURE OF EPIDERMIS, &C. 



Fig. 1. A portion of epidermis taken from the back and 

 outer part of the hand, magnified 100 diameter?, 

 and viewed on its upper surface, showing the 

 elevations by which it is marked, and which are 

 produced by the papillae of the true skin. 



Fig. 2. The same viewed on the under surface, showing the 

 depressions occasioned by the papilla. The number 

 of apertures of the ducts of the sudoriferous and 

 sebacious glands is, in reference to that of the 

 papilla3, about one of the former to six or seven of 

 the latter. 



Fig. 3. A. portion of epidermis magnified 100 diameters, 

 removed from over the pubis of a woman, and dis- 

 playing the apertures of the hair follicles, and the 

 manner in which the hairs issue from them. Some 

 of the follicles contain but a single hair, others two 

 or even three : it is probable that this last is the 

 normal number of hairs enclosed in each follicle 

 wherever situated, but which in the adult is not 

 generally encountered in consequence of the con- 

 tinual removal to which hairs are subject. It is 

 about the apertures of the hair follicles that the 

 scurf is formed, and concerning which a very erro- 

 neous notion prevails, viz, that it is constituted of 

 desquimated epidermis. Scurf does not in the 

 least exhibit the structure of epidermis, but simply 

 consists of the inspissated secretion of the sebacious 

 glands, and many of which, opening into the hair 

 follicles, account for its collection around their 

 orifices. 



