SPECIAL HISTOLOGY. 



OF THE EXTERNAL INTEGUMENT. 



I. OF TE SKIN IN THE STRICTER SENSE. 



A. CUTIS. 



31. The external skin, Integumentum commune (Fig. 45), consists 

 essentially of an internal Fig- 45< 



layer formed principally 

 of connective tissue, and 

 rich in vessels and 

 nerves, the true skin, 

 cutis, derma (Fig. 45, 

 e, d) ; and of an external 

 layer composed of cells 

 only, the epidermis (Fig. 

 45, a, b) ; and it contains 

 in addition many pecu- 

 liar, glandular and horny 

 organs. 



The cutis may be 

 again subdivided into 

 two layers, the subcu- 

 taneous cellular tissue, 

 tela cellulosa subcutanea 

 (Fig. 45, d)-, and the 

 proper corium (Fig. 45, 

 c) ; the latter of which, from its rich nervous and vascular supply, forms 

 the* most important part of the skin. 



32. The subcutaneous cellular tissue is a tolerably firm membrane, 

 constituted chiefly of connective tissue, which in by far the most parts 



FIG. 45. Perpendicular section through the whole skin of the ball of the thumb, trans- 

 versely through three ridges of the cutis: a, horny layer of the epidermis; 6, its mucous 

 layer; e, corium d, panniculus adiposus (upper part) ; e, papillae of the cutis;/, fat masses; g, 

 sudoriparous glands ; A, their canals ; i, sweat-pores. Magnified 20 diameters. 



