60 PLAIN FACTS FOR OLD AND YOUNG 



also known by the offensive odor soon acquired by the 

 sweat if not removed by bathing. 



4. Temperature. The skin performs a very im- 

 portant work in regulating the bodily temperature. 

 The temperature of the interior of the body is always 

 about one hundred degrees, although the surrounding 

 temperature may vary from seven degrees below, to 

 three hundred degrees above. It is through the 

 action of the sweat glands and the evaporation of 

 moisture from the skin that the body is enabled to 

 endure the high degrees of temperature to which it 

 may be subjected, for short periods at least, without 

 injury. 



5. Sensibility. The skin is an organ of sense, giv- 

 ing us information concerning the form and consistence 

 of objects, their temperature, and also the degree of 

 pressure which they exert. Sensibility to pain also 

 serves as a warning to protect other organs of the body 

 from injury. 



The Kidneys.— Imbedded in the tissues of the body, 

 at the back of the abdominal cavity, and a little below 

 the stomach, are placed two of the most important 

 organs of the body, the kidneys. These, though very 

 unlike the skin in appearance, are in some respects 

 closely related to it. 



The kidney is chiefly made up of little round cells, 

 from each of which runs a delicate tube. The tubes run 

 from the outside of the organ inward, joining together 

 to form larger tubes as they approach the center, where 

 they communicate with quite a large cavity, from which 

 a large tube, called the ureter, leads to the bladder. 

 The business of the cells and tubes is to separate from 

 the blood a fluid containing various poisonous sub- 

 stances. 



