68 SUMMAR Y. 



oily matter which they produce is partly spread over the 

 hairs, and partly over the general surface of the skin. 

 A healthy skin is always a little greasy, except on the 

 palms of the hands and the soles of the feet, where there 

 are no hairs and no oil-glands. This oily covering pre- 

 vents the skin from absorbing water when the air is 

 damp; and from drying up on a hot dry day. 



Sometimes the mouth of a sebaceous gland gets choked 

 up, and then its secretion collects in it and becomes dark- 

 colored. In this way little black specks are formed on 

 the skin. They are most frequent on the nose, where 

 the sebaceous glands are large, though the hairs to which 

 they belong are very small. Pressure between the finger- 

 nails will usually easily force out the collected secretion 

 and remove the speck. 



17. Summary. The skin forms a tough, elastic, protec- 

 tive covering for the body, and is also the main organ 

 of the sense of touch. 



It is loosely attached to parts below it, so that it can 

 glide over them in our movements, without being 

 stretched or torn. Beneath it is a cushion of fat which 

 protects the muscles from injury by blows. 



Another use of the fat beneath the skin is to check 

 loss of heat from the body. Warm-blooded animals 

 which live in the sea, as whales, have a very thick layer 

 of fat, known as " blubber," under the skin. This 

 enables them to retain their animal heat in spite of the 

 cold water around them. For the same reason, a fat per- 

 son can bathe longer in cold water without being chilled 

 than one who is thin. 



17. Functions of the skin ? How attached to parts beneath ? Uses 

 of the fat under the skin? Illustrate. Layers of the skin ? Characters 



