344 HANDBOOK OF PHYSIOLOGY. 



but not all, of the papillae contain also one or more terminal nerve-fibres, 

 from the ultimate ramifications of the cutaneous plexus, on which their 

 exquisite sensibility depends. 



The nerve-terminations in the skin are described under the Sen- 

 sory Nerve Terminations. 



Glands of the Skin. The skin possesses glands of two kinds; (a) 

 Sudoriferous, or Sweat Glands; (b) Sebaceous Glands. 



(a) Sudoriferous, or Sweat Glands. Each of these glands consists of 

 a small lobular mass, formed of a coil of tubular gland-duct, surrounded 

 by blood-vessels and imbedded in the subcutaneous adipose tissue (Fig. 

 234, C). From this mass the duct ascends, for a short distance, in a 

 spiral manner through the deeper part of the cutis, then passing straight, 

 and then .sometimes again becoming spiral, it passes through the cuticle 

 and opens by an oblique valve-like aperture. In the parts where the 

 epidermis is thin, the ducts themselves are thinner, and more nearly 



FIG. 235. Terminal tubules of sudoriferous glands, cut in various directions from the skin of 

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



straight in their course (Fig. 234). The duct, which maintains nearly 

 the same diameter throughout, is lined with a layer of columnar epithe- 

 lium (Fig. 235) continuous with the epidermis; while the part which 

 passes through the epidermis is composed of the latter structure only; 

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

 being somewhat differently arranged from those of the adjacent cuticle. 

 The coils or terminal portions of the gland are lined with at least two- 

 layers of short columnar cells with very distinct nuclei (Fig. 235), and 

 possess a large lumen distinctly bounded by a special lining or 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 

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



