SWEAT. 373 



which sinks to a great depth, and passes through the dermis; 

 then, on reaching the adipose panicle, being unable to go 

 farther, winds round itself, and continues to grow until it 

 forms a glomerulus ; this is the coil of the sudoriferous or 

 sweat gland (see Fig. 98). At other times they form larger 

 but less profound growths, terminating in short, rounded culs- 

 de-sac : these are the sebaceous glands ; a vegetation resem- 

 bling this, but on a much larger scale, produces the secretory 

 elements of the mammary gland (Fig. 99 and 100). 



1. Sudoriferous or Sweat Glands and Perspiration. The 

 sweat glands are very numerous : it has been estimated that 

 no fewer than from two to three millions of them are spread 

 over the surface of the body. 1 They are found almost every- 

 where, the greater number being in the folds of the cutaneous 

 surface : in the armpit they form a sort of reddish continu- 

 ous layer; they are not found on the inner surface of the 

 pinna of the ear, while in the external auditory canal they 

 form a circle of large glands placed close together (cerumi- 

 nous glands). 



The tube which forms these glands has about the diameter 

 of a very fine hair : it is at first rolled up (glomerulus) in the 

 depth of the dermis ; then, becoming straight again, passes 

 through the dermis and continues as a tube, a simple inter- 

 cellular lacuna, which passes like a corkscrew through the 

 epidermis (Figs. 97 and 98). The average total length of 

 one of these tubes is two millimetres ; if, therefore, all the 

 sudoriferous tubes were placed end to end, their total length 

 would be four kilometres: the total mass of the sudoriferous 

 system has, therefore, been estimated at half that of the kid- 

 ney, or a quarter of the whole renal system ; these figures 

 serve to show the relative importance of these two classes of 

 secretory glands. 



The fluid secreted by the sudoriferous glands has never 

 been collected in a perfectly pure state, because, in spreading 

 over the epidermis it mingles with other products of this 



1 Sappey counted nearly 120 orifices of sudoriferous glands in a 

 square centimetre in parts of the body where the epidermis is thin. 

 They are still more numerous (nearly 300 to a square centimetre) 

 in the plantar and palmar regions. Their total number, according 

 to these calculations, must reach two millions: "it even exceeds 

 this number, although, in making this estimate, we have not taken 

 into account the glands of the arm-pit, which are still more numer- 

 ous than those of the hand or the foot, and occupy a circulating 

 surface of only three or four cm. in diameter " (Sappey). 



