WATER 193 



in a spiral manner to the surface of the skin. It 

 has been estimated, that if all these glands, which 

 a body of average size contains, were placed end to 

 end, they would reach twenty-eight miles. What a 

 remarkable arrangement this system of glands is ! 

 How important it is that they should always be in 

 the best condition for work can be judged from the 

 fact that with the kidneys and lungs they form the 

 sewers through which the water of the body and any 

 substances that it has taken into solution are dis- 

 charged. Great pains are taken to prevent the sewer 

 pipes of a dwelling from becoming clogged, and when 

 for any cause they are stopped up, no time is lost in 

 clearing away the obstruction. That we should be 

 even more particular with the sewer pipes of our bodies 

 can be easily understood. 



It is well known that waste water given out through 

 the pores is commonly spoken of as sweat or perspir- 

 ation. On warm days or when we are exercising 

 violently, perspiration can be seen or felt on the skin. 

 At other times the pores of a healthy skin give out 

 water, but in such small quantities that it is called 

 insensible perspiration. Like watery vapor from. the 

 lungs, it sometimes has a disagreeable odor which is 

 noticed after perspiring freely. Though the water 

 evaporates, substances that it had in solution remain 

 on the skin or underclothing. But what other use have 

 these miles of pores ? They perform another great ser- 

 vice in so regulating the body's heat that in health it 



