556 



THE SKIN. 



interlacing, and freely supplied with small nuclei along the fibers. 

 The boundary line toward the epithelium is slightly fringed, as 

 seen where the papillary layer is withdrawn from the rete 

 mucosum ; sometimes a hyaline, so-called structureless, layer may 

 be observed. (See Fig. 231.) The papillae are prolongations of 

 the derma, varying greatly in size and shape in diif erent localities 

 of the integument. The largest and most numerous papillae, 

 composed of a number of filiform elevations which coalesce 

 into a more bulky basis, are found on the palmar surface of the 

 hands and the plantar surface of the feet. In other places they 

 form small conical or blunt protrusions. The papillae are every- 



FIG. 231. PAPILLARY LAYER OF THE SKIN OF A CHILD. 

 VERTICAL SECTION. 



The papillae are artificially separated from the covering epithelium. E, epidermis; JR, 

 rete mucosum ; C, row of columnar epithelia nearest to the connective tissue ; P, papillae, 

 composed of delicate fibrous connective tissue; L, longitudinal; T, transverse section of 

 bundles. The blood-vessels injected. Magnified 500 diameters. 



where arranged in rows, between which crossing furrows are 

 present, visible to the naked eye, produced by a peculiar arrange- 

 ment of the connective-tissue fibers, which is also marked on the 

 outer epidermal surface. The rows formed by the groupings 

 of the papillae are especially well marked in the palms of the 



