SUBCUTANEOUS TISSUE. 153 



very prominently as consisting of three or four layers of 

 flattened, lenticular, or (in cross-section) fusiform cells, which 

 are dark, stain very deeply, and contain coarse granules of a 

 substance called eleidin, supposed to be a precursor of the 

 horny substance of the more superficial cells of the epidermis. 



The stratum lucidum is a thin, translucent layer of horny, 

 flattened cells, lying on the stratum granulosum, and forming 

 the lowest layer of the horny portion of the epidermis. It 

 is often indistinct. 



The stratum corneum consists of numerous layers of flat, 

 squamous cells, and forms the thick, outer, horny layer of the 

 epidermis. The cells consist of a hard, horny substance, or 

 keratin, into which the protoplasm of the underlying cells has 

 become converted. There is practically no vitality left in 

 these cells, but they are well adapted to protective purposes. 

 In vertical section the cells appear as a succession of wavy 

 lines, with occasional indistinct traces of the degenerated 

 nuclei. 



The corium, cutis vera, or dennis, is the connective-tissue 

 portion of the skin, of mesoblastic derivation. It is a firm 

 fibrous layer, corresponding to the tunica propria of mucous 

 membranes, and is thicker than the epidermis ; to it the firm- 

 ness of the skin is due. It consists of an interlacing network 

 of white and some elastic fibres, among which are scattered 

 fusiform connective-tissue cells ; mingled with these are numer- 

 ous capillaries, small lymph-vessels, and nervous elements. 



The upper surface of the corium presents numerous oval 

 papiUce projecting upward into the stratum Malpighii, which 

 fills the intervals between them. Some of the papillae are 

 occupied by capillary loops, others by tactile nerve-terminals. 

 In some situations the papilla? are closely crowded, in others 

 more sparsely. The arrangement of the papilla? gives rise to 

 the lines of the palm and sole, and to other superficial mark- 

 ings elsewhere. 



The lower surface of the corium is plane and merges into 

 the subcutaneous tissue. 



The subcutaneous tissue (or superficial fascia) is a layer of 

 loose areolar and adipose tissue which underlies the corium 

 and extends to the subjacent structures. It varies in thick- 

 ness in different parts of the body, and corresponds to the 



