OP THE GLANDS OF THE SKIN. 



201 



running longitudinally, whose elements are easily separable, as muscu- 

 lar fibre-cells of 0-015-0-04 of a line long, 0-002-0-005, or even 0-008 

 of a line broad, occasionally with a few pigment-granules, and each con- 

 taining a roundish elongated nucleus. Whenever the glandular tubes con- 



rig. 79. 



tain only fluid, the epithelium is a single very distinct layer of polygo- 

 nal cells of 0-006-0-015 of a line ; in the opposite case it can be seen 

 only with difficulty or not at all. With respect to the occurrence of 

 these two forms of glandular canals, the thick muscular walls are found, 

 especially in the large glands of the axilla, whose cells all possess mus- 

 cular walls, and thence acquire a very peculiar striated appearance. I 

 have noticed a precisely similar structure only in the large glands of the 

 root of the penis and of the nipple, although it is true that there is 

 occasionally a muscular development, but slighter and only partial, in the 

 glands of the palm, whose wide canals are distinguished by the thickness 

 of their walls, and exhibit a muscular structure distinctly enough, though 

 thinner than elsewhere. The same description applies to certain glands 

 of the scrotum, and even of the back, of the labia majora, of the mons 

 veneris, and of the neighborhood of the anus ; yet with this limitation, 

 that often only a small part of the glandular tube, perhaps merely its 

 caecal extremity, is provided with a muscular coat. The glands of the 

 leg, of the penis, of the thorax (the areola excepted), of the eyelids, and 

 the majority of those of the back and thigh, of the chest and abdomen, 

 as well as of the two prominent segments of the upper extremity, are 

 delicate and without muscles. 



The diameter of the glandular canals varies, in the smaller glands from 

 0-022-0-04 of a line, and is about 0-03 of a line on the average ; the 



FIG. 79. Sweat ducts ; magnified 350 diameters. A, one with thin walls and a central cavity 

 without a muscular coat, from the hand : a, connective investment ; 6, epithelium ; r, cavity. 

 JB, a portion of a canal without a cavity, and with a delicate muscular layer, from the scro- 

 tum : a, connective tissue; 6, muscular layer; c, cells which fill the glandular canal with 

 yellow granules among their contents. 



