ORGANS OF SENSE. 147 



■vfith a coarse towel or hair mitten. The deeper structure of the cuticle 

 consists of softer scales or flattened cells, and the portion in immediate 

 cointact with, the true skin is in an almost semi-fluid state, containing cells 

 and nuclei. This fluid lymph or blastema contains numerous cell germs or 

 cytoblasts, which gradually enlarge into cells which lie close together, and 

 cover every portion of the papillary surface of the cutis. As soon as the 

 first layer is formed, a second is formed immediately beneath it, separating 

 it from the true skin, and causing its drying and desquamation. The 

 superficial scales adhere by their fedges ; the middle laminas of cells by their 

 surfaces-, the deep-seated are supported immediately by thin blastema. 



Granules of coloring matter are* found distributed among the deeper cells 

 ajid in the connecting lymph, and it is upon the amount and tint of these 

 that the complexion of the skin depends. In the Negro and other dark- 

 colored races, this coloring matter appears as a layer of pigment ; it is not, 

 however, a distinct or organized membrane, but merely coloring matter 

 deposited in the interstices of the cells ; as the latter approach the surface, 

 any coloring matter they carry along with them is lost as they become dry 

 and hard, partly by evaporation, partly by undergoing some chemical 

 change. 



The cuticle being itself insensible and unvascular, forms a most useful 

 investment to the body, defending a highly sensitive surface from pressure 

 and friction, and from the stimulating efi'ects of the atmosphere. It is also 

 invaluable in resisting the evaporation of the fluids of the cutis. 



2. Dermis, Chorion, or Cutis Vera. This is composed essentially of 

 areolar tissue condensed into a firm, compact membrane, in which is inter- 

 woven more or less of the yellow elastic fibrous tissue, with numerous 

 vessels and nerves. Its inferior surface is loose, open, and cellular, con- 

 nected and continuous with the areolar tissue of the subjacent parts without 

 any very exact limitation or distinction ; the subdermoid cellular tissue 

 contains the cutaneous glands and hair bulbs, and the vascular and nervous 

 ramifications which are to supjDly the dermis, as also more or less of adipose 

 tissue. This subcutaneous adipose tissue or fat differs in diflerent indivi- 

 duals, according to age, sex, and constitution ; it is usually softer and more 

 abundant in the female, and at its maximum in the child. 



In the dermis, the upper portion, called the superßx:ial or papillary 

 lamina (although not a separate layer), presents a condensation of the 

 areolar tissue into a smooth membranous surface which is exquisitely 

 vascular and sensible, and presents beneath the epidermis numerous minute 

 elevated lines called papillae. This lamina is the seat of a vascular capil- 

 lary plexus, and in the living body appears uniformly red when the cuticle 

 has been detached. The papillae are studded over this surface, varying in 

 number and size in different parts of the body ; the tactual sensibility of 

 different parts of the body is in proportion to the abundance and size 

 .of these papillae. Thus on the lower surface of the fingers the skin presents 

 numerous curved or arched grooves and ridges ; each ridge consists of a 

 row of conical papillae, and into the intervening grooves the epidermis sinks, 

 and the small exhalant pores open. The exact structure of the papillae ig 



853 



