THE OUTER SKIN. 



319 



a compact layer, the so-called corium, and a deeper-lying loose 

 layer, the tela subcutanea. 



The boundary between the connective-tissue part and the 

 epidermis is usually uneven. This is caused by the fact that 

 the corium immediately under the epidermis is raised into con- 

 ical or round papillae (Figs. 241, 243, 244). These extend into 

 the epidermis, and are of different size in various parts of the 

 body. The largest are in the planta pedis, vola rnanus, glans 

 penis, etc., where they reach a height of 0.2 mm. In other 



FIG. 242. 



8tr. cor- 



r. gran- 

 ules um 

 St. ger- 

 minal. 



Corinm 



Diagrammatic section through the skin. This figure serves to show how the section 

 in Fig. 240 is cut. The line x-y gives the direction of the section. S, sweat gland ; 

 P, papilla ; M, Meissner's corpuscle. 



places (e. g., in the skin of the face) they are inconspicuous. 

 We divide the papillae, according to whether they contain 

 loops of blood capillaries or nerve corpuscles, into vascular and 

 nervous papillae. 



The corium consists of white fibrous connective tissue, the 

 fibre bundles of which cross one another in different directions. 

 In the network thus formed we find connective-tissue cells of 

 various kinds, and a plexus of elastic fibres which is denser 

 in the deeper layers. 



The corium may be divided into two layers : the pars 

 papillaris and the pars reticularis. The first, which lies imme- 

 diately under the epidermis, owes its name to the fact that it 

 contains the papillae ; while the pars reticularis is so named 

 on account of the net-like arrangement of the connective-tissue 

 bundles. These bundles cross one another in such a way that 

 there are left rhomboidal spaces or meshes (Lange's spaces), 

 which are filled with sweat glands or fat. The two layers of 

 the corium pass into one another without any sharp line of 

 demarcation. 



