THE HUMAN ORGANISM 



289 



of expressions that go with various emotions ("register," as 

 the motion-picture people say), most of us cannot help showing 

 in our faces what is happening to our feelings. 



Since they constitute so large a portion of the whole body, 

 the muscles influence the whole organism by determining the 

 rate and vigor of many other functions— the circulation of the 



i2v 



QJ!.-, 



Fig. 143. What is good posture ? 



It is possible to give you good rules about the position of the neck and chest and 

 back and feet; but these rules are mechanical and treat the human being as you 

 would a machine or an animal that you want to train. Unless you already have bad 

 habits of standing and walking and sitting, the best rule is to take up positions that, 

 in the first place, are free from physical strain and that, in the next place, carry a 

 feeling of confidence, courage, determination, and good cheer 



blood, breathing, and the rate at which waste products are elimi- 

 nated through the skin, the lungs, and the kidneys. Expansions 

 and contractions of the muscles, aside from increasing the de- 

 mand upon supplies of food and oxygen, bring about mechanical 

 stimulations of the intestines and so promote their well-being. 

 For all these reasons, then, modern man must keep his muscles 

 not only in working condition but actually at work. All our 

 labor-saving devices have made it possible to shift more and 



