TABLE OF CONTENTS XI 



PROBLEM PAGE 



VI. What Are the Reasons for, and the Best Methods op 



Ventilation? 409 



VII. What Are the Organs of Excretion and How Do They 



Function? 411 



UNIT XIV. HOW HAS MAN BECOME THE CON- 

 QUEROR OF THE WORLD? 

 I. What Are the Chief Responses of Plants and Animals? 422 

 II. How Do Simple Plants and Animals Respond to Stimuli? 424 



III. What Are Sense Organs and What Do They Do? . . 427 



IV. How Is Man's Body Controlled? 429 



V. What Part Do the Sense Organs Play in the Control 



of the Body? . 435 



VI. What Behaviors Are Instinctive? 441 



VII. How Are Habits Formed? 443 



VIII. What Are Some Good Health Habits? .... 447 



IX. What Are Some Effects of the Drink Habit? . . . 449 



PART V 



MAN'S INTER-RELATIONSHIP WITH OTHER 

 LIVING THINGS 



UNIT XV. HOW DOES MAN CONTROL HIS ENVIRON- 

 MENT FOR HEALTH? 



I. How May We Control the Growth of Bacteria? . . 457 



II. How Do Bacteria Cause Disease? 461 



III. How Do We Get Bacterial Diseases? .... 463 



IV. Why Is Quarantine Necessary? . . . . . . 471 



V. What Is Immunity? 474 



VI. What Are the Differences between Active and Passive 



Immunity? 476 



VII. How Is Malaria Caused and Transmitted? . . . 482 

 VIII. How Was the Cause and Control of Yellow Fever 



Discovered? 487 



IX. What Are Other Disease Carriers and What Diseases 



Do They Carry? 489 



X. What Diseases Are Caused by Worms and How May 



We Fight Them? . . . 492 



XL How May We Improve Conditions at Home? . . . 497 

 XII. How May We Improve Conditions at School? . . .501 



XIII. How May We Help Improve Conditions in Our Com- 



munity? 503 



XIV. What Protective Health Agencies Should Exist in a 



Community? 507 



