29G 



HITCHCOCK'S ANATOMY 



521. Epidermis or Cuticle; Has no Vitality —Pigment 

 Cells —Composition of Pigment-Cells. — The outer layer of 

 the skin is called the Cuticle or Epidermis, and bears the 

 same relation to the true skin, that the outer bark of the tree 

 does to the inner. In thickness it varies considerably in the 

 different parts of the body. It is » -J 77th of an inch thick on 

 the chin, cheeks and brows, and T ^th to £th of an inch thick 

 on the soles of the foot. It is merely a layer of albumen — 



FiG. 287. Fig. 288. 



Vertical Section of Epidermis from a Highly magnified Pigment-Cells. A. 

 Negro, a, Deep Cells loaded with Pig- Scales of the Epidermis filled with Pig- 

 ment. Cells more elevated and some- ment Cells which are seen separate at b. 

 what flattened, c, Scaly Cells at the Sur- B. Pigment Cells from the Choroid Coat 

 face. of the Eye. 



the same substance as the white of an egg — and is secreted 

 by the true skin, in the form of scales, which are closely 

 compacted together, and it is in this form that they are de- 

 tached from the body by washing and friction. In some 

 cases, however, it is detached in large patches, so that after 

 certain skin diseases have run their career, the whole epider- 

 mis of the hand with the nails adherent may be removed in 

 the manner of a glove. The epidermis contains no blood- 

 vessels or nerves, and consequently no vitality, it being merely 

 a secretion which hardens into a semi-transparent membrane. 

 A part of the cells of the true skin, however, instead of se- 

 creting the epidermis, produce what are termed the Pigment 



521. Describe the epidermis. To what does it correspond in the tree? State its thick- 

 ness and chemical composition. What vessels and what cells does it contain? Where 

 are the pigment cells shown ? 



