148 ANTHROPOLOGY. 



dÜBcult to ascertain ; each appears to be an eminence or projection of the 

 superficial laminas of the cutis, with some portion of the fibro-cellular tissue 

 containing blood-vessels, and most probably nerves. The vessels appear 

 as convoluted loops, and constitute the greater portion of the papillae ; 

 nerves also can be traced through the cutis to each papilla. These accord- 

 ingly may be considered as the true organs of tact. 



The excreting apparatus of the skin consists of glands and follicles, some 

 of which sujDply the perspiration or sweat, others the sebaceous secretion 

 or oily matter. 



The sudoriferous or sweat glands exist in all parts of the body, imbedded 

 irt' the dermis or the subdermoid tissue. Each consists of a convoluted 

 tube closed at its inferior extremity, the other end becoming the fine exha- 

 lant duct which passes in an oblique or spiral course through the cutis and 

 cuticle, and opens by a minute pore ; it is lined by a fine epithelium con- 

 tinuous with the cuticle. 



The sebaceous glands^ though not so numerous as the last, are very gene- 

 rally difi"used through all parts of the skin except the palms of the hands 

 and soles of the feet. They arc very distinct in the auditory meatus 

 [glandes ceruininosoi\ on the inner aspect of the eyelids {glandes Meiho- 

 miancc\ also on the scalp, face, and tip of the nose, around the nipples, and 

 about the anus, scrotum, and corona glandis {glandes odoriferce). They 

 are small, round bodies, imbedded in the dermis ; some are simple, soft, 

 convoluted tubes, others are firm and lobulated. In the scalp and other 

 parts where the hairs exist, one or more of them open into the hair follicles. 

 A minute parasitic animal, the Demodex folliculorum, has been found to 

 inhabit these ducts exclusively. The sebaceous secretion serves to keep 

 the surface moist, soft, and pliant, and in particular situations, as in the ear, 

 eyelids, nipples, «Sec, it answers special purposes; it also co-operates with the 

 sudoriferous glands in separating hydro-carbonous matters from the blood. 



The hair and nails are appendages of the skin, but are rather modifica- 

 tions of the cuticle than allied to the true skin. 



3. The Nails cover the dorsal surface of the last phalanges of the fingers 

 and toes, and have a tendency to extend around the extremity of each. 

 They are strong, elastic, insensible plates, curved or concave so as to fit 

 closely the cutis ; the root and borders are concealed and fixed in a narrow 

 deep fold in the cutis, termed the nail follicle ; the exposed portion or body 

 is convex and ends in the free margin. The surface of the cutis to which 

 the body of the nail adheres is called the matrix, and is so vascular that the 

 red color is seen through the nail ; at the root and a short distance beyond 

 it, it is less vascular and more dense, and causes the semi-lunar white spot 

 at the base of the nail, called the lunida. The absence of this lunula is 

 said to characterize the colored races, as distinguished from the white. In 

 the follicle, at the root and borders, are a number of papillae Avhich form 

 the nail by secreting the blastema in which are formed cell germs ; these 

 become flattened and compressed, dry, and harden into nail. As the nail 

 etongates, it thickens by additions to its concave surface from the matrix, 

 ■and increases in breadth by secretion along its borders. The cuticle is 

 854 



