354 



EXCRETION BY THE SKIN AND KIDNEYS. 



skin covering the concave surface of the concha of the ear, the glans penis, 

 the inner lamella of the prepuce, and unless the ceruminous glands be re- 

 garded as sudoriparous organs, in the external auditory meatus. 



On examining the surface of the skin with a low magnifying power, espe- 

 cially on the palms of the hands and the soles of the feet, the orifices of the 



sudoriferous ducts may be seen in the mid- 

 dle of the papillary ridges, forming a regu- 

 lar line in the shallow groove between the 

 two rows of papillae. The tubes always 

 open upon the surface obliquely. In a thin 

 section of the skin, the ducts are seen pass- 

 ing through the different layers and ter- 

 minating in rounded, convoluted coils in 

 the subcutaneous structure. These little, 

 rounded or ovoid bodies, which are the su- 

 doriparous, or sweat-producing structures, 

 FIG. in. Surface of the palm of the hand, maybe seen attached to the under surface 



a portion of the skin about one half an , n , . -, .,T -, -,/. 



inch (is-? mm.) square ; magnified 4 di- of the skin when it has been removed from 



i,i,Monsothe sudoriferous ducte; the subjacent parts by maceration. A per- 

 of'thlskif r ovesbetween the papillae spiratory gland consists, indeed, of a simple 



tube, presenting a coiled mass, the sudorip- 

 arous portion, beneath the skin, and a tube of greater or less length, in pro- 

 portion to the thickness of the cutaneous layers, which is the excretory duct, 

 or the sudoriferous portion. 



The glandular coils are yj^ to ^ of an inch (O2 to 1 mm.) in diameter ; 

 the smallest coils being found beneath the skin of the penis, the scrotum, the 

 eyelids, the nose and the convex surface of the concha of the ear, and the 

 largest, on the areola of the nipple and the perineum. Very large glands are 

 found mixed with smaller ones in the axilla, and these produce a peculiar 

 secretion. The coiled portion of the tube is about -^ of an inch (0-07 mm.) 

 in diameter, and presents six to twelve turns. It consists of a sharply defined, 

 strong, external membrane, which is very transparent, uniformly granular and 

 sometimes indistinctly striated. The tube is of uniform diameter throughout 

 the coil and terminates in a very slightly dilated, rounded, blind extremity. 

 It is filled with epithelium in the form of finely granular matter, usually not 

 segmented into cells, and is provided with small, oval nuclei. The glandular 

 mass is surrounded by a plexus of capillary blood-vessels, which send a few 

 small branches between the convolutions of the coil. Sometimes the coil is 

 enclosed in a delicate fibrous envelope. 



The excretory duct is simply a continuation of the glandular coil. Its 

 course through the layers of the true skin is nearly straight. It then passes 

 into the epidermis, between the papillae of the corium, and presents, in this 

 layer, a number of spiral turns. The spirals vary in number according to 

 the thickness of the epidermis. Six to ten are found in the palms of the 

 hands and twelve to fifteen in the soles of the feet (Sappey). As it emerges 

 from the glandular coil, the excretory duct is somewhat narrower than the 



