394 EXCRETION 



The duct is lined with a layer of columnar epithelium continuous with 

 the epidermis. The coiled or secreting portion of the gland is lined with 

 at least two layers of short columnar cells with very distinct nuclei, figure 306. 

 The lumen is distinctly bounded by a special lining of cuticle. 



The sudoriferous glands are abundantly distributed over the whole sur- 

 face of the body; but are especially numerous, as well as very large, in the 

 skin of the palm of the hand and of the sole of the foot. The glands by 

 which the peculiarly odorous matter of the axillae and groin is secreted form 

 a nearly complete layer under the cutis, and are like the ordinary sudoriferous 

 glands, except in being larger and having very short ducts. 



The peculiar bitter yellow substance secreted by the skin of the external 

 auditory passage is named cerumen, and the glands themselves ceruminous 

 glands; but they do not much differ in structure from the ordinary sudorif- 

 erous glands. 



The sebaceous glands, figures 305 and 306, like sudoriferous glands, are 

 abundant in most parts of the surface of the body, particularly in parts largely 



FIG. 307. Sebaceous Gland from Human Skin. (Klein and Noble Smith.) 



supplied with hair, as the scalp and face. They are thickly distributed about 

 the entrances of the various passages into the body, as the anus, nose, lips, 

 and external ear. They are entirely absent from the palmar surface of the 

 hand and the plantar surface of the foot. They are racemose glands com- 

 posed of an aggregate of small tubes or sacculi lined with columnar epithelium 



