APPENDAGES OF THE SKIN. GOT 



The Sebaceous Glands are small, sacculated, glandular organs, lodged in the 

 substance of the corium or sub-dermoid tissue. They are found in most parts of 

 the skin, but are most abundant in the scalp and face ; they are also very numerous 

 around the apertures of the anus, nose, mouth, and external ear ; but are wanting 

 in the palms of the hands, and the soles of the feet. Each gland consists of a 

 single duct, more or less capacious, which terminates in a lobulated pouch-like 

 extremity. The basement membrane forming the wall of the sac, as well as the 

 duct, is lined by epithelium, which is filled with particles of sebaceous matter ; 

 and this becoming detached into the cavity of the sac, as its growth is renewed, 

 constitutes the secretion. The number of sacculi connected with each duct vary 

 from two to five, or even twenty, in number. The orifices of the ducts open most 

 frequently into the hair-follicles, but occasionally upon the general surface. On 

 the' nose and face, the glands are of large size, distinctly lobulated, and often 

 become much enlarged from the accumulation of pent-up secretion. The largest 

 sebaceous glands are those found in the eyelid, the Meibomian glands. 



The Sudoriferous or /Sweat-glands are the organs by which a large portion of 

 the aqueous and gaseous materials are excreted by the skin. They are found in 

 almost every part of the skin, and are situated in small pits in the deep parts of 

 the corium, or in the subcutaneous areolar tissue, surrounded by a quantity 

 of adipose tissue. They are small, lobular, reddish bodies, consisting of one or 

 more convoluted tubuli, from which the efferent duct proceeds upwards through 

 the corium and cuticle, and opens upon the surface by a slightly enlarged orifice. 

 The efferent duct, as it passes through the corium, pursues, for a short distance, a 

 spiral course, becoming straight in the more superficial part of this layer, and 

 opens on the surface of the cuticle by an oblique valve-like aperture. In the 

 parts where the epidermis is thin, the ducts are finer and almost straight in their 

 course ; but where the epidermis is thicker, they assume again a spiral arrange- 

 ment, the separate windings of the tube being as close and as regular as those of 

 a common screw. The spiral course of these ducts is especially distinct in the thick 

 cuticle of the palm of the hand and sole of the foot. The size of these glands 

 varies. They are especially large in those regions where the amount of perspira- 

 tion is great, as in the axillae, where they form a thin mammillated layer of a 

 reddish color, which corresponds exactly to the situation of the hair in this 

 region ; they are large, also, in the groin. Their number varies : they are most 

 numerous on the palm of the hand, and present, according to Krause, 2,800 

 orifices on a square inch of the integument, and a rather less number on the sole 

 of the foot. In both of these situations, the orifices of the ducts are exceedingly 

 regular, and correspond to the small transverse grooves which intersect the ridges 

 of papilla. In other situations they are more irregularly scattered, but in nearly 

 equal numbers over parts including the same extent of surface. In the neck and 

 back they are least numerous, their number amounting to 417 on the square inch 

 (Krause). Their total number is estimated by the same writer at 2,381,248 ; and 

 supposing the aperture of each gland to represent a surface of 5 ' 5 of a line in 

 diameter, he calculates that the whole of these glands would present an evaporat- 

 ing surface of about eight square inches. 



Each gland consists of a single tube intricately convoluted, at one end termi- 

 nating by a blind extremity ; at the other end opening upon the surface of the 

 skin. In the larger glands, this single duct usually divides and subdivides 

 dichotomously ; the smaller ducts ultimately terminating in short ca3cal pouches, 

 rarely anastomosing. The wall of the duct is thick ; the width of the canal rarely 

 exceeding one-third of its diameter. The tube, both in the gland and where it 

 forms the excretory duct, consists of two layers : an outer, formed by fine areolar 

 tissue ; and an epithelium lining its interior. The external or fibro-cellular coat 

 is thin, continuous with the superficial layer of the corium, and extends only as 

 high as the surface of the true skin. The epithelial lining is much thicker, con- 

 tinuous with the epidermis, and alone forms the spiral portion of the tube. When 

 the cuticle is carefully removed from the surface of the cutis, these convoluted 



