DIGESTION.] 



PHYSIOLOGY, 



105 



knife were very sharp and you very skilful, you might 

 do the same in every part of your skin. If you were 

 to put some of the skin you had thus cut off under 

 the microscope, you would find that it was made up 

 of little scales. And if you were to take a very thin 

 upright slice running through the whole thickness of 

 the skin, and ^examine that under a high power of the 

 microscope, you would find that the skin was made 

 up of two quite different parts or layers, as shown in 

 Fig. te;. The upper layer, ^, ^, is nothing but a mass 

 of little bodies packed closely together. At the top 

 they are pressed fiat into scales, but lower down they 

 are round or oval, and at the same time soft. They 

 are called cells. As you advance in your study of 

 Physiology you will hear more and more about cells. 

 This' layer of cellSj either soft and round, or flattened 

 and dried into scales, is called the epidermis. No 

 blood-vessel is ever found in the epidermis, and hence, 

 when you cut it, it never bleeds. As long as you live 

 it is always growing. The top scales are always being 

 rubbed off. Whenever you wash your hands, especially 

 with soap, you wash off some of the top scales ; and 

 you would soon wash your skin away, were it not that 

 new round cells are always being formed at the bottom 

 of the epidermis, along the line at d (Fig. 15), and 

 always moving up to the top, where they become dried 

 into scales. Thus the skin, or more strictly the 

 epidermis, is always being renewed. Sometimes, as 

 after scarlet fever, the new skin grows quickly, and 

 the old skin comes away in great flakes or patches. 



The lower layer below the epidermis aS what is 

 called the dermis, or true skin. This is full of 

 capillaries and blood-vessels, and when the knife or 



