OF THE SUDORIPAROUS GLANDS. 



237 



Transverse section of human hair, magnified 

 200 diameters. 



the basement membrane, of small angular cells, scarcely larger than their 

 Fig. 106. nuclei. At d these cells are more bulky, 



and the bulb consequently thicker : there 

 is also pigment developed in them ; above 

 d they assume a decidedly fibrous char- 

 acter, and become condensed ; 0, a mass of 

 cells in the axis of the hair, much loaded 

 with pigment. (Todd and Bowman.) 



Fig. 105 is an engraving of a photo- 

 graph of a transverse section of human 

 hair from the head. The outer line 

 shows the cortex ; in some the pigment- 

 ary axis is seen ; in most, however, it is 

 absent. 



The SUDORIPAROUS GLANDS originate in depressions of the cutis or 

 tissues beneath, occurring in some parts, as in the axilla, The SU( ioripa- 

 more numerously than in others. They consist of a tube rous glands. 

 wound on itself, and sometimes dividing in convoluted* branches. The 

 knot thus arising is contained in a cell, the wall of which is copiously 

 supplied with blood-vessels : the duct passes through the superjacent tis- 

 sues. The tube is formed of a cylinder of basement mem- 

 brane lined with epithelium. The basement membrane 

 may be considered to be derived from the outer surface of 

 the papillae, and the epithelium is an external projection of 

 the cuticle. The duct, on its passage outward, loses its 

 basement membrane as it escapes between the papilla; 

 and it has a spiral or helical aspect, an arrangement prob- 

 ably intended to keep the calibre open. It is estimated 

 that the number of sudoriparous glands is about seven mill- 

 ions, and the total length of their tubing about 28 miles. 



Fig. 106 is a sudoriparous gland from the palm of the 

 hand : <z, a, knot of tubes with two excretory ducts, b, b, 

 uniting into a helical canal, which perforates the epidermis 

 at , and opens on its surface at d : the gland is imbedded 

 in fat vesicles at e, e, e, e. (Wagner.) 



The SEBACEOUS GLANDS are distributed in different 

 ed2o giand, abundance in various parts, their office being The sebaceous 



to lubricate the hair, to keep the skin in a flex- s lands - 

 ible condition, and avoid the inconveniences of friction. Their ducts 

 open either into the hair follicles or upon the cuticular surface ; the gland 

 consisting of basement membrane lined with epithelium, the cells of 

 which, as they reach maturity, become filled with a sebaceous or oily ma- 

 terial. The ear glands of this class secrete a waxy matter. 



