CHAP. XIV.] THE SKIN. 405 



the dense and altered areolar tissue constitutes by far the largest 

 proportion of the cutis derma or cutis vera. 



The external surface of the skin, formed by the cuticle, 

 (which everywhere adapts itself to the form of the surface on 

 which it rests), is marked by furrows of various kinds. Some 

 of these (furrows of motion) occupy the neighbourhood of joints, 

 especially on the side of flexion, and are generally transverse, 

 facilitating the formation and determining the position of the folds 

 that result from the movements of one segment of a limb on 

 another. Others correspond to the insertion of cutaneous muscles ; 

 for example, many of those which give force and character to the 

 features ; and these are much modified by the quantity of subja- 

 cent fat. The elevator muscle of the lower lip thus causes the 

 t( double chin." Furrows of another kind are seen in aged and 

 emaciated persons, and after the subsidence of any great distension 

 of the integument, such as that occasioned by anasarca or preg- 

 nancy. But, besides these coarser lines, almost every part of 

 the skin is grooved by numberless very minute furrows, which 

 in the more highly developed regions run in nearly parallel curved 

 lines, and elsewhere assume a stellated arrangement, or form a 

 close interlacement of no regular figure. These lines are important, 

 as they depend upon peculiarities in the texture of the skin, having 

 particular relation to the sense of touch : they may be best studied 

 on the palmar aspect of the hand and fingers, and on the sole of the 

 foot. The outer surface of the skin likewise presents innumerable 

 pores, the orifices of the sebaceous follicles and sudoriferous ducts ; 

 and the various modifications of the epidermis, termed ' ' appendages 

 of the skin," as hairs, nails, etc., all project on the same aspect. 



The deep surface of the skin is formed by the cutis, or cutis 

 vera, and is attached to the parts which it invests by an extension of 

 the areolar tissue, of which it is itself principally composed, as well 

 as by vessels, nerves, and sometimes muscular fibres, passing into its 

 substance from the subjacent region. It is on this surface that the 

 sweat-glands rest; they are imbedded in it more or less deeply, 

 according to their size, and the length of their excreting ducts ; and 

 together with the fatty pellets, so abundant in most parts of the 

 subcutaneous fascia, occasion that areolar or cribriform appearance, 

 which is seen on this aspect of a cleanly dissected portion of integu- 

 ment. In preparing such a specimen, it is at once made evident, 

 however great the difference may seem to be between the dense and 

 closely woven texture of the cutis and the lax fascia to which it 

 owes its mobility on subjacent organs, that these tissues blend 



