438 



PRACTICAL ANATOMY. 



below the papillary ; it merges with the superficial fascia, 

 to which it is attached by connective tissue. The areolar 

 layer contains within its meshes fat- vesicles, sweat-glands, 

 hair-follicles, and serves as a nidus for the ramification 

 of vessels and nerves. 



The hair and nails are appendages of the skin and 

 consist of modifications of the epidermis. The sebaceous 

 glands secrete the sebum, an oily substance which lubri- 

 cates the skin. They consist of small, racemose glands, 

 and frequently open in a hair-follicle. 



FIG. 193. VARIOUS KINDS OF EPITHKLIAL, CELLS. 



A, columnar cells of intestine : B, polyhedral cells of the conjunctiva ; C, ciliated coni- 

 cal cells of the trachea ; D, ciliated cell of frog's mouth ; E, inverted conical cell of trachea ; 

 F, squamous cell of the cavity of the mouth, seen from its broad surface ; G, squamous cell, 

 seen edgeways. 



The sweat-glands are tubular, excretory glands. They 

 have a long duct leading from the gland, which lies in the 

 subcutaneous connective tissue. The nerves terminate 

 in the skin in three different ways : ( 1 ) the Pacchionian 

 corpuscles, (2) the bulbs of Krause, and (3) the tactile 

 corpuscles of Wagner. 



1. The Pacchionian corpuscles are ovoidal masses of 

 fibrous tissue, containing within a central canal a termi- 

 nal axis-cylinder. They are about T ^ 7 inch in diameter, 

 and are found principally in the connective tissue of the 

 fingers and toes. 2. The end bulbs of Krause are 



