208 THE SKIN 



This is especially true if one is fatigued, as then one is 

 liable to cramps of the muscles. 



Soaps. Some skins are more sensitive than others 

 and become roughened by much washing, especially with 

 strong soaps which contain enough free alkali to be irri- 

 tating. This can be avoided if care is taken to use 

 a neutral soap, such as a good castile, and to replace the 

 oil of the skin by diluted glycerine or other emollient. 1 



Skin parasites. The skin is sometimes irritated by 

 parasites of both animal and vegetable nature, which, 

 when once established, are difficult to remove. It is 

 therefore important to be cleanly oneself and to avoid 

 contact with those who are not, that such parasites may 

 not get a foothold. 



Skin eruptions. A number of contagious diseases, 

 i3uch as measles, scarlet fever, small-pox and chicken-pox, 

 are accompanied by eruptions of the skin. All eruptions, 

 therefore, which appear suddenly and are accompanied 

 by such other symptoms of illness as headache, chills, 

 cold in the head and sore throat, should be looked into 

 at once. The person should be isolated, especially from 

 children, until it has been definitely determined by a 

 physician that the cause is not a contagious disease. 



EXPERIMENTS AND DEMONSTRATIONS 



Materials : Piece of glass ; ink roll, or dabber ; printers' ink ; 

 dull and sharp knives; stiff nail brush; soaps soft, yellow, 

 castile, etc.; vinegar; various kinds of leather; hair of dog, 

 horse, etc. ; fur of cat, rabbit, etc. ; feathers ; fish scales ; micro- 

 scope ; magnifying glass 2 ; litmus paper. 



1 Glycerine should be used in a solution of about three or four 

 parts of water to one of glycerine. Emollients are best applied at 

 night, while the skin is still moist after bathing. 



- In the following experiments, all examinations should be made, 

 if possible, with both a magnifying glass and a microscope. 



