THE SKIN. 603 



interlacing bundles of white fibrous tissue, intermixed with a much smaller pro- 

 portion of yellow elastic fibres, the amount of which varies in different parts. 

 The fibro-areolar tissue is more abundant in the deeper layers of the cutis, where 

 it is dense and firm, the meshes being large, and gradually becoming blended with 

 the subcutaneous areolar tissue ; towards the surface, the fibres become finer and 

 more closely interlaced, the most superficial layer being covered with numerous 

 small, conical, vascular eminences, the papilla?. From these differences in the 

 structure of the cutis at different parts, it is usual to describe it as consisting of 

 two layers ; the deep layer or corium, and the superficial or papillary layer. 



The corium, consists of strong interlacing fibrous bands, composed chiefly of 

 the white variety of fibrous tissue ; but containing, also, some fibres of the yeRow 

 elastic tissue, which vary in amount in different parts. Towards the attached 

 surface, the fasciculi are large and coarse ; and the areolaB left by their interlacing 

 large and occupied by adipose tissue and the sweat-glands. This element of 

 the skin becomes gradually blended with the subcutaneous areolar tissue. Towards 

 the free surface, the fasciculi are much finer, and they have a closer interlacing, 

 the most superficial layers consisting of a transparent, homogeneous matrix with 

 imbedded nuclei. 



The corium varies in thickness, from a quarter of a line to a line and a half, in 

 different parts of the body. Thus, it is thicker in the more exposed regions, as 

 the palm of the hand and sole of the foot ; on the posterior aspect of the body, 

 than the front ; and on the outer side of the limbs than the inner. In the eye- 

 lids, scrotum, and penis, it is exceedingly thin and delicate. The skin generally 

 is thicker in the male than in the female. 



The areolse are occupied by adipose tissue, hair follicles, and the sudatory and 

 sebaceous glands; they are the channel by which the vessels and nerves are 

 distributed to the more superficial strata of the corium, and to the papillary 

 layer. 



Plain muscular fibres are found in the superficial layers of the corium, where- 

 ever hairs are found ; and in the subcutaneous areolar tissue of the scrotum, penis, 

 perineum, and areolae of the nipple. In the latter situations, the fibres are arranged 

 in bands, closely reticulated and disposed in superimposed laminas. 



The papillary layer is situated upon the free surface of the corium ; it consists 

 of numerous small, highly sensitive, and vascular eminences, the papillae, which 1 

 rise perpendicularly from its surface, and form the essential element of the organ 

 of touch. The papillae are conical-shaped eminences, having a round or blunted 

 extremity, occasionally divided into two or more parts, and connected by their 

 base with the free surface of the corium. Their average length is about T ^th 

 of an inch, and they measure at their base about ssfjth of an inch in diameter. 

 On the general surface of the body, more especially in those parts which are 

 endowed with slight sensibility, they are few in number, short, exceedingly minute, 

 and irregularly scattered over the surface ; but in other situations, as upon the 

 palmar surface of the hands and fingers, upon the plantar surface of the feet and 

 toes, and around the nipple, they are long, of large size, closely aggregated 

 together, and arranged in parallel curved lines, 'forming the elevated ridges seen 

 on the free surface of the epidermis. In these ridges, the larger papillae are 

 arranged in a double row, with smaller papillae between them ; and these rows are 

 subdivided into small square-shaped masses by short transverse furrows regularly 

 disposed, in the centre of each of which is the minute orifice of the duct of a 

 sweat-gland. No papillae exist in the grooves between the ridges. In structure 

 the papillae resemble the superficial layer of the cutis ; consisting of a homogeneous 

 tissue, faintly fibrillated, and containing a few fine elastic fibres. The smaller 

 papillae contain a single capillary loop ; but in the larger the vessels are convoluted 

 to a greater or less degree ; each papilla also contains one or more nerve fibres* 

 but the mode in which these terminate is uncertain. In those parts in which the 

 sense of touch is highly developed, as in the lips and palm of the hand, the 

 nerve fibres appear to have some intimate connection with an oval-shaped body, 



