BIOLOGY APPLIED TO HEALTHFUL LIVING 533 



SKIN 



457. Skin Cleanliness. The scientific reason for clean- 

 ing the skin, especially by the use of soap in warm water, is 

 that it removes dirt, which is objectionable primarily be- 

 cause it is unsesthetic and therefore disagreeable to refined 

 people, and secondarily, because dirt contains micro-organisms 

 which may produce disease. In fact, dirty hands have often 

 caused typhoid and other dangerous disease^ by leaving 

 bacteria on dishes and on foods. Formerly it was supposed 

 that a third reason for cleansing the skin with soap was to re- 

 move substances which " clog the pores of the skin and keep 

 in excretions"; but, as we have seen in 446, the skin has 

 little to do with excretions except as water is incidentally 

 eliminated while the skin is reducing the internal heat, hence 

 " keeping the pores open " is a weak argument for cleaning 

 the skin. The fact is that the pores " open " quickly, even 

 on the dirtiest skin, when exercise develops excess of heat. 

 However, we do not need the unscientific theory of " keeping 

 pores open"; for the aesthetic and bacteriological reasons 

 named above are sufficient to convince any civilized person, 

 and especially any one who sees the force of the rule, " use 

 soap because refined people do so and the barbarians do 

 not." This is more sensible than trying to show that soap 

 is necessary for hygienic reasons, for there are healthy 

 people who never or rarely use soap. Such health is not 

 surprising, for soap has very much to do with aesthetics and 

 little with health, except in possible bacterial infections. 



The abuse of soap by many refined people deserves atten- 

 tion. Exposed parts of the body must be washed very fre- 

 quently with soap, and preferably with warm water ; but a 

 complete bath with soap and warm water is taken too fre- 

 quently by many persons. Soap removes the oily secretions 

 and the warm water dilates the blood-vessels of the skin, 

 increasing liability to colds. A warm soapy tub-bath once 



