260 APPLIED PHYSIOLOGY 



of the proper degree to cause it to feel soft and pliable. Its appearance 

 is changed by ill health. If the stomach and intestine are not in good 

 order, it is almost impossible for the skin to be beautiful. Plain food, 

 fresh air, and exercise make a beautiful skin, and no skin can be beauti- 

 ful without them. Cold dry air or exposure to the sun's rays often 

 cause it to become red or to blister. These effects are much greater 

 upon those who are unaccustomed to the exposure. 



465. Care of the complexion. Washing the skin with soft 

 water and soap as often as it becomes dirty, and following it by a 

 thorough drying with a soft towel, are the only effective means of 

 beautifying the skin. Paint, powder, and perfumery cannot cause the 



'skin to grow more beautiful. They simply coat its outside, and at the 

 same time stop its sebaceous and sweat glands, so that when, it is 

 removed the skin looks worse than before. They act like any other 

 dirt. Many of these preparations contain poisonous minerals such as 

 lead. 



Drugs taken internally to beautify the skin act mainly through the 

 arsenic which they contain. Arsenic destroys the blood cells, and so 

 gives a peculiar paleness to the skin. Paleness is only a sign of poison- 

 ing which is working harm to the health. 



466. Absorbent power of the skin. Since the outer part 

 of the epidermis is dry and dead and contains no blood 

 tubes or lymphatics, substances rubbed upon the skin 

 will not be absorbed. So man can handle virulent poisons 

 and disease germs without danger. On the other hand, 

 when the epithelium is removed, the exposed blood tubes 

 and lymphatics take up drugs and poisons very readily. 

 Drugs may be absorbed from surgical dressings, and germs 

 of disease may enter through even a minute scratch. 



467. Care of the hair. The hair of man, like that of animals, 

 is soft and glossy in health, but often dry and rough during disease. 

 Daily brushing to remove the dirt, and to distribute the oily secretion 

 of the sebaceous glands, will keep the hair in the best condition. All 

 that is necessary beyond this is frequent washing with soft water. The 

 secretion of the sebaceous glands is sufficient to oil the hair and scalp. 

 There is no substance which will cause hair to grow, neither will any 



