THE SWEAT-GLANDS. 



491 







glandular coil, and ascend vertically through the corium, penetrating 

 between the papilla into the epithelium. Here they twist like a 

 corkscrew, and, according to the thickness of the cuticle, make two 

 to sixteen spiral turns, and ter- 

 minate by small round or funnel- 

 shaped apertures (3 J to 2 Jo of 

 an inch), called the sweat-pores, 

 on the free surface of the cuticle. 

 (Fig. 328.) They retain their epi- 

 thelium, consisting of at least 

 two layers of cells, till they reach 

 the surface of the corium. But 

 while traversing the stratum Mal- 

 pighii and the cuticle, they are 

 merely bounded by layers of 

 cells. Sometimes the excretory 

 ducts of two glands unite into 

 one. (Krause.) 



These glands are developed ori- 

 ginally as solid flask-shaped pro- 

 cesses of the stratum Malpighii 

 projecting into the corium, and 

 are very similar to the hair-sacs. 

 They first appear in the fifth 

 month of embryonic life. At 

 the seventh month the sweat- 

 duct is seen perforating the cu- 

 ticle, and the gland has pene- 

 trated downwards to the inner 

 portion of the corium, and be- 

 come bent like a hook, indicative 

 of the future coils. Soon after 

 this, the gland acquires the ap- 

 pearance it presents in the adult, 

 and probably no new ones are 

 developed after birth. 



The secretion afforded by the 

 sudoriferous glands has already 

 been described (p. 229). 



The ceruminous glands of the ear may be regarded, histologi- 



A. Ve rtical section of the cuticle, frtm the heel 

 detached by maceration. The epithelium of the 

 sweat-duct continuous with the cuticle has been 

 drawn out of the tube of basement-membrane , as 

 far as to the gland, where it begins to be contorted. 

 The cavity of the duct is seen dilating as it enters 

 the cuticle, and then stretching up to the surface 

 through the epidermic laminae. The deep surface 

 of the duct is continuous with the surface of the 

 cavities in which the papillae are lodged. 6. Duct 

 at its entrance into the cuticle, more highly mag- 

 (Magnified 35 diameters.) 



