SUMMARY. 69 



The skin consists of two layers. The outer or epidermis 

 is not sensitive and contains no blood. The outer part of 

 the epidermis is dry, horny, and dead. It is constantly 

 being shed. 



The deeper layer of the epidermis is moist, and, being 

 well nourished by liquid soaked up from the blood-ves- 

 sels of the dermis, grows fast and makes new cells which 

 are pushed on towards the surface to take the place of 

 those of the outer layer which are shed or rubbed off. 



The dermis contains many nerves and much blood. 

 An important use of the epidermis is to cover and pro- 

 tect it. If there were no epidermis, our whole surface 

 would feel like the "raw" skin at the bottom of a blister. 



Nails are made by great growth of the horny layer of 

 the epidermis. Their function is protective. 



Hairs are scattered over nearly the whole skin. They 

 are threads of epidermis developed from the bottom of 

 little pits in the skin. When large and abundant, as on 

 the head, they protect from cold and blows. Even when 

 small and few, they are useful by aiding in the sense of 

 touch. 



Glands are hollow organs which make special liquids. 

 The liquid made by a gland is called a secretion, and is 

 poured out through a tube, the duct of the gland, on 

 some surface outside or inside the body. The sweat- 

 glands and the oil-glands pour their secretion on the 

 skin. 



The sweat-glands are most active when the body is 

 warm, and help to keej^it at its proper temperature. 



of outer layer of epidermis ? Deeper layer? Characters of dermis? 

 How epidermis protects the dermis? Nails? Hairs? Uses? 

 Glands? Secretions? Ducts? Glands of the skin? Use of sweat- 

 glands ? Of oil-glands ? 



