THE SKIN -EPIDERMIS. 



21 



On examining the thickness of the skin, we first find on 

 the surface a thin transparent membrane, a sort of organic 

 varnish, designed to receive the contact of the air and of 

 external objects. This is the epidermis. Elastic and very 



Fig. io. The Skin. 



A. Section of skin under the microscope. 



a b. Superficial and deep layers of epidermis. 



c. Dermis true skin. 



(/. Fatty areas of the deeper portions of the dermis. 



d. Muscular layer subjacent to t)ie skin. 

 t e' . Sweat glands and ducts. 



f. Hair-follicle and sebaceous gland. 



B. Hair seen under the microscope. 



flexible, it lends itself to every movement of the skin, pro- 

 tecting its exquisite sensibility and modifying its property of 

 rapidly absorbing gases and soluble bodies. Although this 

 membrane is so thin, we can discover a superficial or 

 horny layer and two deeper layers. The first, the true 

 epidermis, thickens and becomes callous under the influence 

 of rubbing or pressure, as for instance on . the heel. The 

 other two layers are the mucous network of Malpighi and the 

 pigmentary layer. It is in the substance of this last especially 

 that the//w/z/, the colouring matter of the skin, is developed. 



