ccxvi SWEAT GLANDS. 



The sudoriferous glands or sweat-glands (figs. cxxm. and cxxiv.). These 

 are seated on the under surface of the coriura. and at variable depths in the 

 subcutaneous adipose tissue. They have the appearance of small round 

 reddish bodies, each of which, when examined with the microscope, is found 

 to consist of a fine tube, coiled up into a ball (though sometimes forming 

 an irregular or flattened figure), from which the tube is continued, as the 

 duct of the gland, upwards through the true skin and cuticle, and opens on 

 the surface by a slightly widened orifice. The duct, as it passes through 

 the epidermis, is twisted like a corkscrew, that is, in parts where the epi- 

 dermis is sufficiently thick to give room for this ; lower down it is but 

 slightly curved. Sometimes the duct is formed of two coiled up branches 

 which join at a short distance from the gland, as happens to be the case 

 in the specimen represented in figure cxxiv. The tube, both in the gland 

 and where it forms the excretory duct, consists of an outer coat, continuous 

 with the corium, and reaching no higher than the surface of the true skin, 

 a thin homogeneous membrana propria, and an epithelial lining, consisting 

 of one or more strata of cells (often containing brownish pigment), and con- 

 tinuous with the epidermis, which alone forms the twisted part of the duct. 

 The outer, dermic or fibrous, coat is formed of homogeneous or finely 

 fibrous connective tissue with corpuscles. The larger gland-ducts in. the 

 axilla, at the root of the penis, on the labia majora, and in the neighbour- 

 hood of the anus, contain between their coats a layer of non-striated mus- 

 cular fibres arranged longitudinally. In the larger glands, moreover, the 

 duct is rarely simple, being more usually parted by repeated dichotomous 

 division into several branches, which before ending give off short csecal 

 processes ; in rare cases the branches anastomose. On carefully detaching 

 the cuticle from the true skin, after its connection has been loosened by 

 putrefaction, it usually happens that the cuticular linings of the sweat-ducts 

 get separated from their interior to a certain depth, and are drawn out in 

 form of short threads attached to the under surface of the epidermis. The 

 coils of the duct are loosely held together by connective tissue, which may 

 form a sort of capsule round the body of the gland. Each little sweat-gland 

 is supplied with a dense cluster of capillary blood-vessels. 



The contents of the smaller sweat-glands are fluid, without any formed elements ; but 

 in the larger sweat-glands of the axilla the contents are semi-fluid, and abound in fine 

 pale granules and nuclei ; or their secretion is extremely viscid, with a varying quan- 

 tity of large, opaque, colourless, or yellow granules, with nuclei and cells, similar to 

 epithelium-cells ; and in both cases it may also contain fat. Kb'lliker states that from 

 the nature of their contents these larger glands might be separated into a distinct 

 group from the ordinary sweat-glands, were it not for the presence of transitional forms. 



Distribution. Sweat-glands exist in all regions of the skin, and attempts have been 

 made to determine their relative amount in different parts, for they are not equally 

 abundant everywhere ; but, while it is easy to count their numbers in a given space on 

 the palm and sole, the numerical proportion assigned to them in most other regions must 

 be taken with considerable allowance. According to Krause, nearly 2,800 open on a 

 square inch of the palm of the hand, and somewhat fewer on an equal extent of the sole 

 of the foot. He assigns rather more than half this number to a square inch on the back 

 of the hand, and not quite so many to an equal portion of surface on the forehead, and 

 the front and sides of the neck ; then come the breast, abdomen, and fore-arm, where 

 he reckons about 1100 to the inch, and lastly, the lower limbs and the back part of 

 the neck and trunk, on which the number in the same space is not more than from 

 400 to 600. 



The size of the sweat-glands also varies. According to the observer last named, 

 the average diameter of the round-shaped ones is about one-sixth of a line; but in 

 some parts they are larger than this as, for example, in the groin, but especially in 



