FIG. 946. Body of a sudoriferous-gland cut in various 

 directions, a. Longitudinal section of the proximal part 

 of the coiled tube. 6. Transverse section of the same. 

 c. Longitudinal section of the diatal part of the coiled 

 tube. d. Transverse section of the same. (Klein and 

 Noble Smith.) 



1070 ORGANS OF THE SENSES AND THE COMMON INTEGUMENT 



the glands are of large size, distinctly tabulated, and often become much enlarged 

 from the accumulation of pent-up secretion. The tarsal glands of the eyelids are 

 elongated sebaceous glands with numerous lateral diverticula. 



The Sudoriferous or Sweat Glands (glandules sudoriferce) are found in almost 

 every part of the skin, and are situated in small pits on the under surface of the 

 corium, or, more frequently, in the subcutaneous areolar tissue, surrounded by a 

 quantity of adipose tissue. Each consists of a single tube, the deep part of which 

 is rolled into an oval or spherical ball, named the body of the gland, while the super- 

 ficial part, or duct, traverses the corium 

 and cuticle and opens on the surface of 

 the skin by a funnel-shaped aperture. 

 In the superficial layers of the corium 

 the duct is straight, but in the deeper 

 layers it is convoluted or even twisted; 

 where the epidermis is thick, as in the 

 palms of the hands and soles of the feet, 

 the part of the duct which passes through 

 it is spirally coiled. The size of the 

 glands varies. They are especially large 

 in those regions W 7 here the amount of 

 perspiration is great, as in the axillae, 

 where they form a thin, mammillated 

 layer of a reddish color, which corre- 

 sponds exactly to the situation of the 

 hair in this region; they are large also 

 in the groin. Their number varies. 

 They are very plentiful on the palms 



of the hands, and on the soles of the feet, where the orifices of the ducts are exceed- 

 ingly regular, and open on the curved ridges; they are least numerous in the neck 

 and back. On the palm there are about 370 per square centimeter; on the back of 

 the hand about 200; forehead 175, breast, abdomen and forearm 155, and on the 

 leg and back from 60 to 80 per square centimeter. Krause estimates the total 

 number at about 2,000,000. The average number of sweat glands per square 

 centimeter of skin area in various races as shown by the fingers is as follows : l 



American (white) 558.2 



American (negro) 597.2 



Filipino 653.6 



Moro 684.4 



Negrito (adult) 709.2 



Hindu 738.2 



Negrito (youth) 950.0 



They are absent in the deeper portion of the external auditory meatus, the pre- 

 puce and the glans penis. The tube, both in the body of the gland and in the duct 

 consists of two layers an outer, of fine areolar tissue, and an inner of epithelium 

 (Fig. 946). The outer layer is thin and is continuous with the superficial stratum of 

 the corium. In body of the gland the epithelium consists of a single layer of cubical 

 cells, between the deep ends of which and the basement membrane is a layer 

 of longitudinally or obliquely arranged non-striped muscular fibers. The ducts are 

 destitute of muscular fibers and are composed of a basement membrane lined by two 

 or three layers of polyhedral cells; the lumen of the duct is coated by a thin cuticle. 

 When the cuticle is carefully removed from the surface of the corium, the ducts 

 may be drawn out in the form of short, thread-like processes on its under surface. 

 The ceruminous glands of the external acoustic meatus and the ciliary glands at 

 the margins of the eyelids are modified sudoriferous glands. 



1 Clark and Lhamon, Anatomical Record, 1917, xii. 





