HOW IS THE HUMAN MACHINE PROTECTED? 361 



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Hairs and How They Grow. Have you ever looked at 

 the back of your hand when it was held in a strong light ? 

 If so, you noticed many hairs growing there. Although 

 these hairs are thicker or longer in some parts of the body, 

 we can find them growing almost everywhere from the 

 skin. They grow as the 

 accompanying diagram 

 shows, from little pits in 

 the dermis, or inner skin. 

 At the base of each hair 

 are found tiny collections 

 of cells which form oil 

 called oil glands. These 

 lubricate the hairs. Since 

 the openings of these 

 glands may become 

 clogged with dirt, sur- 

 faces covered with hair 

 should be washed fre- 

 quently. 



Care of the Hair. The 

 simplest method of car- 

 ing for the hair is brush- 

 ing. Whether the hair is 

 long or short, both boys 

 and girls should brush 

 their hair thoroughly 

 every day. This keeps 

 the scalp stimulated and 

 free from dirt or dandruff. It also distributes the natural 

 oil from the scalp over the length of the hair and makes 

 it look glossy and healthy. Wetting the hair with water 

 every day to keep it in place is a bad habit, which has 

 often been blamed for early baldness. Unruly hair may 

 be trained into place by the use of a light oily dressing. 



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A section cut through a hair. In which 

 layer of the skin do hairs grow ? 



