i 



THE NERVOUS SYSTEM 117 



or choice of his daily acts. As such he is a " thinking " animal 

 and has become master of the earth. 



Summary. — As we progress from simple forms of animal Ufe 

 toward more complex forms, we note an increasing complexity in 

 the division of labor. But no matter how simple or how complex 

 the animal, all have certain functions, and in the many-celled ani- 

 mals we find definite organs of sensation, protection, locomotion, 

 food-taking, digestion, circulation, respiration, excretion, nervous 

 control, and reproduction. In the human body these organs are 

 most highly developed. 



One of the organs of protection, the skin, must be cared for 

 properly if we wish to keep it healthy. Skin infections sometimes 

 prove very serious. The hygiene of muscles, bones, and posture 

 is of importance, especially to growing children. 



Problem Questions 



1. Give different examples of division of labor from your own experience. 

 Is there division of labor in society? 



2. In what respects is a frog like man in structure? 



3. What functions are common to all animals? To many-celled ani- 

 mals ? To animals and plants ? 



4. In what respects is the body like a machine? 



5. What is the proper first-aid treatment for an infected wound ? Why? 



6. Why is flatfoot an important defect? 



7. Of what use to man is the nervous system ? 



Problem and Project References 



Hunter, Laboratory Problems in Civic Biology. American Book Company. 



Davison, The Human Body and Health. American Book Company. 



Holmes, Biology of the Frog. The Macmillan Company. 



Hough and Sedgwick, The Human Mechanism. Ginn and Company. 



Howell, Physiology. W. B. Saunders Company. 



Martin, The Human Body, Advanced Course. Henry Holt and Company, 



Sharp, Foundation of Health. Lea and Febiger. 



Stiles, Human Physiology. W, B. Saunders Company. 



WilUams, Text-Book of Anatomy and Physiology. W. B. Saunders Company. 



H. NEW CIV. BIOL. 



