THE SKIN. 



557 



hands and the soles of the feet, giving rise to the graceful spiral 

 and concentric lines observed on the skin covering the last 

 phalanges. 



In horizontal sections of the skin the papillae appear as light, 

 circular, or oblong fields, marked by the presence of transverse or 

 oblique sections of the capillary blood-vessels in their central 

 parts. The depressions between the papillae are filled with epi- 

 thelia, which, being arranged in the form of an interpapillary 

 reticulum, have given rise to the inappropriate name "rete 

 mucosum." (See Fig. 232.) 



According to J. Collins Warren,* the papillae are imperfectly 

 formed on the posterior aspect of the body. The follicles of the 

 lanugo hairs penetrate the superficial layers of the derma, the 

 sweep of whose fibers would be unbroken were it not for the 



FIG. 232. SCALP OF A COLORED MAN. HORIZONTAL SECTION. 



R, rete mucosum ; Pi, row of columnar epithelia, cut obliquely, supplied with dark- 

 brown pigment granules ; Pa, papilla, cut transversely ; D, derma. Magnified 500 

 diameters. 



existence of a structure which connects the bases of the hair 

 follicles with the panniculus adiposus. This consists of a col- 

 umnar cleft extending from the subcutaneous tissue in a some- 

 what oblique direction through the cutis to the base of the hair 

 follicle. This cleft is filled with adipose tissue, hence the term 

 " fat-column " is appropriate for its designation. Its long axis is 

 placed at a slight angle to that of the follicle, and is nearly 

 parallel to that of the arrector pili muscle. The number of fat- 

 columns corresponds to the number of hairs. They are seen 



* "A Manual of Histology." By Thorn. E. Satterthwaite, New-York, 1881. 



