CHAP. XIV.] 



THE SWEAT-GLANDS. 



423 



On detaching one of these glands, and highly magnifying it, it is 

 seen to consist of a solitary tube intricately ravelled, one end of which 

 is closed, and usually buried within the gland ; the other emerges 

 from the gland, and opens on the skin. Sometimes this tube is 

 branched, but its diameter is usually very uniform from end to end. 

 When very long, the open end m g . 



forming the duct is a little 

 wider than the rest. The wall 

 is comparatively thick, so that 

 the calibre is not more than 

 a third of the whole diame- 

 ter. It consists, like the cor- 

 responding part of most other 

 glands, of two layers : an outer 

 or basement membrane, with 

 which the vessels are in con- 

 tact ; and an epithelium, lining 

 the interior. The basement 

 membrane is extremely thin, 

 and is continuous with the 

 outer surface of the papillse. 

 The epithelium is much thicker, 

 and is an involution of the epi- 

 dermis that rests on the papillae 

 and dips in between them. 

 Hence the tube, traced out- 

 wards from the gland, loses the 

 basement membrane at the sur- 

 face of the papillae ; and the re- 

 mainder of its course is pursued 

 upwards through the successive 

 laminae of cuticular scales. 



The preparation exhibited in 



fig. 91 shows the Continuity of Vertical section of the cuticle from the heel, 



. , -, . T detached by maceration as in fig. 79. The epithe- 



thC epithelium lining the ex- Hum of the sweat-duct, continuous with the cuticle, 



,, , . has been drawn out of the tube basement, mem- 



Creting part OI the dUCt With brane, as far as the gland, where it begins to be con- 



. , , , T i tortcd. The cavity of the duct is seen dilating as it 



the CUtlCle, aild alSO diSClOSeS its enters the cuticle, and then stretching- up to the snr- 



, 1 face through the epidermic laminae. The deep sur- 



hardness and cuticular charac- lace of the duct is continuous with the surface of the 



..,., . p cavities in which the papillse are lodged. Magn. 35 



tcr, quite different from that of diam. 



. . 6. Duct at its entrance into the cuticle. More 



the secreting epithelium within highly magnified. 



the gland, which is soft and easily decomposed. We have remarked 



that the duct, in traversing the layers of the cuticle, is lined by 



