viii BIOLOGY AND HUMAN LIFE 



THE CONTROL OF THE BODY 



CHAPTER PAGE 



XXII. The Nervous System 216 



XXIII. The Special Sense Organs 226 



XXIV. Hygiene of the Sense Organs 235 



XXV. Instincts and Habits 241 



XXVI. The Emotions 251 



XXVII. The Meaning of Health 261 



XXVIII. The Human Organism and Keeping it Fit . . . 272 



INTERMEZZO. MAN'S DEPENDENCE 



CONTROL OF THE ENVIRONMENT FOR HEALTH 



XXIX. How Diseases are Caused 299 



XXX. Microbes and their Control 307 



XXXI. Insects in Relation to Disease 317 



XXXII. Worms and Other Controllable Disease Agents . 332 



XXXIII. Artificial Immunity in the Control of Disease . 338 



XXXIV. Community Activities related TO Health . . 351 

 XXXV. The Home in Relation to Health 365 



XXXVI. Industrial Problems of Health 379 



XXXVII. Organization of Activities for Protecting Health 398 



XXXVIII. The Day's Work in Relation to Health . . . 406 



PART III. THE BIOLOGY OF WEALTH 



INTERMEZZO. WEALTH 



PRODUCTION 



XXXIX. Plants and Animals as Sources of Useful Ma- 

 terials 415 



XL. Classes of Plants and their Economic Importance 429 

 XLI. Classes of Animals and their Economic Im- 

 portance 448 



