SKIN AND ITS APPENDAGES. 



125 



FIG. 19. 



The structure of the skin consists of three membranes 

 the cutis vera, rete mucosum, and cuticle. 



The cutis-vera, or true skin, 

 is the innermost layer of the 

 three. It is the chief mem- 

 brane; is the thickest and 

 strongest, and is regarded as 

 the basis to the other two. Ac- 

 cording to M. M. Beclard and 

 Bayle, it is composed of cel- 

 lulo-fibrous structure, in the 

 form of an areolar web, more 

 or less compact that is, its 

 cellular fibres, more or less 

 interwoven with the fibrous, 

 form a firm, compact mem- 

 brane, varying in thickness 

 from one-quarter of a line to one line and a half. Its 

 thickness in the trunk is greater behind than before ; in 

 the limbs greater externally than internally; it is remark- 

 ably dense in the palms of the hands and soles of the feet, 

 and particularly thin in the eye-lids,, mammse, scrotum and 

 penis. We find the cellular and fibrous tissue varying in 

 their relative proportions in different parts, and in accord- 

 ance with the amount of motion and resistance to press- 

 ure; the cellular predominating where freedom of motion 

 is required, as in the axillae, while the ligamentous or 

 fibrous is most abundant where there is greatest pressure, 

 as in the plantar and palmar regions; and it is in conse- 

 quence of this combination of the cellular and ligamentous 

 tissue in the cutis-vera, that we find it possessed of the 



FIG. 19 represents the structure of the skin, a Epiderma, or cuticle, b 

 Rete-mucosum. c Papillary clumps, quadrilateral in shape, composed of coni- 

 cal papillae, and seen in the palm of the hand and sole of the foot, d Deep 

 layer of derma, the corium. e Adipose cells. / Sudoriparous gland, with its 

 spiral duct, g Sudoriparous gland, with a straighter duct, as seen in the scalp. 

 h Two hairs from the scalp, enclosed in their follicles, i A pair of sebi-parous 

 glands, opening by short ducts into the follicle of the hair. 



