EXCKETION. 493 



layer of columnar epithelium (fig. 311) continuous with the epidermis; 

 while the part which passes through the epidermis is a mere passage 

 through the epidermal cells not being bounded by any special lining; 

 but the cells which immediately form the boundary of the canal in this 

 part are somewhat differently arranged from those of the adjacent cuti- 

 cle. The coils or terminal portions of the gland are lined with at least 

 two layers of short columnar cells with very distinct nuclei (fig. 312), 

 and possess a large lumen distinctly bounded by a special lining of 

 cuticle. 



The sudoriferous glands are abundantly distributed over the whole 

 surface 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 peculiar odorous matter of the axillae is secreted 



Fig. 812. Terminal tubules of sudoriferous glands, cut in various directions from the skin of the 



pig's ear. (V. D. Harris.) 



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 ex- 

 ternal auditory passage is named cerumen, and the glands themselves 

 ceruminous glands; but they do not much differ in structure from the 

 ordinary sudoriferous glands. 



(b) Sebaceous Glands. -The sebaceous glands (figs. 311, 316), like 

 sudoriferous glands, are abundant in most parts of the surface of the 

 body, particularly in parts largely 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 surfaces of the feet. They are racemose glands composed of an 

 aggregate of small tubes or sacculi lined with columnar epithelium and 

 filled with an opaque white substance, like soft ointment, which consists 

 of broken-up epithelial cells which have undergone fatty degeneration. 

 Minute capillary vessels overspread them; and their ducts open on 



