GENERAL OBSERVATIONS 49 



The Sudoriferous or Sweat Glands are composed of 

 coiled tubes which lie in the deeper portion of the skin, 

 and send up a corkscrew-like duct to open on the surface 

 of the epidermis. They are numerous over the whole of 

 the body. 



The Human Nails are thickenings of the lowermost layer 

 of the horny portion of the epidermis, the stratum lucidum. 

 They are developed over a modified portion of the corium 

 known as the nail-bed. The horny substance of the nail 

 is composed of clear horny cells, and rests immediately 



Fig. 25. — Longitudinal Section through Nail and Nail-bed 

 OF A Human Fcetal Finger.* 



a, The nail ; h, the rete mucosum ; c, the longitudinal ridges of the corium. 



upon a Malpighian layer similar to that found in the 

 epidermis generally. Instead of the papillfe present else- 

 where in the skin, the corium of the nail-bed is marked 

 by longitudinal ridges, a similar, though less distinct, 

 arrangement to that found in the laminae of the horse's 

 foot. 



* Seeing that the section is a longitudinal one, it would appear from 

 the way the ridges cut that they are running transversely beneath 

 the nail. Their extreme delicacy, however, prevents a single one 

 showing itself along the length of the section, and their constant 

 accidental cutting makes them appear to run transversely (H. C. R.). 



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