SUDORIPAROUS GLANDS 317 



about 3-1} of an inch (0.07 millimeter) in diameter, and presents six to 

 twelve turns. It consists of a sharply-defined strong external mem- 

 brane, which is very transparent, uniformly granular and sometimes in- 

 distinctly striated. The tube is of uniform diameter throughout the coil 

 and terminates in a very slightly-dilated, rounded, blind extremity. It 

 > 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 with a plexus of capillary bloodvessels, 

 which send a few small branches between the convolutions of the coil. 

 Sometimes the coil is enclosed in a delicate fibrous envelope (see 

 Plate VII, Fig. 2). 



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 pre- 

 sents, 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. As it emerges from the glandular coil, the excretory duct is some- 

 what narrower than the tube in the secreting portion ; but as it passes 

 through the epidermis it again becomes larger. It possesses the same 

 external membrane as the glandular coil and is lined usually by two 

 layers of cells. 



In a section of the skin and the subcutaneous tissue, involving 

 several of the sudoriparous glands with their ducts, it is seen that the 

 glandular coils nearly always are situated at different planes beneath the 

 skin. 



Sudoriparous glands in the axilla have been described which do not 

 differ so much from the glands in other parts in their anatomy as in the 

 character of their secretion. The coil in these glands is much larger 

 than in other parts, measuring % to ^ of an inch (i to 2 millimeters) ; 

 the t walls of the tube are thicker, and they present an investment of 

 fibrous tissue with an internal layer of longitudinal non-striated muscu- 

 lar fibres ; and finally, the tubes of the coil itself are lined with cells of 

 epithelium. These glands are abundant in the axilla, forming a continu- 

 ous layer beneath the skin. Mixed with these are a few glands of the 

 ordinary variety. 



Estimates have been made of the number of sudoriparous glands in 

 the body and the probable extent of the exhalant surface of the skin, 

 but they are to be taken as approximate. Krause found great differ- 

 ences in the number of perspiratory openings in different portions of the 

 skin ; but taking an average for the entire surface, it was estimated that- 

 the entire number of perspiratory glands is 2,381,248; and assuming 



