PREFACE 



Our secondary schools today are common schools in the sense that ele- 

 mentary schools were common fift)' years ago. That is, they enroll somewhat 

 over two thirds of the boys and girls of the age they are designed to serve. In 

 the past our high schools were responsible for special services to boys and 

 girls who were in line for careers in the professions or for leadership in their 

 communities. Today our high schools must furnish guidance, instruction 

 and training of value to everybody. We have tried in this book to introduce 

 a unified science of living things, which we regard as a valuable part of our 

 common heritage. 



Like the traditional three R's of our common schools, this introduction 

 opens the way for all, expecting that each will continue as far as he wishes or 

 needs to along particular lines. Some will wish to go further with botany 

 or entomology, for example, or with gardening or breeding, whether as a 

 hobby or as a profession. Some will wish to become nurses or technicians, 

 physicians or administrators, and so will follow their "biology" in different 

 directions. And some will find that this book will serve as a solid and ample 

 foundation for college work. 



These young men and women honestly want to understand the essential 

 facts of personal and social life and the practical implications of these facts 

 for themselves. These students are already on the verge of being the adult 

 workers and voters and policy-makers of their time. They will have to 

 decide scores of issues involving human beings as organisms — organisms that 

 want food and shelter, that want to be well and to prolong their lives, that 

 have to live together without destroying one another. These young men and 

 women want to know more about the human species than they can possibly 

 get out of the specialized subjects that ignore the organic nature of man, 

 and more than they can possibly get out of a "biology" that ignores the 

 distinctively human characteristics of this particular species — its intellect, its 

 imagination, its inventiveness, its emotions and sentiments, and the very 

 sociality that makes it possible for us to have any science at all. 



We have accordingly tried to depict life in terms sufficiently broad to 

 include man himself and sufficiently concrete to be within the grasp of the 

 common mind. This has meant developing the material from points of view 

 that are generally meaningful, the familiar functions, activities and relation- 

 ships of living things: eating and breathing, growing and maturing, origins 

 and developments and death, health and sickness, the helps and hindrances 

 to life that come from the inanimate world and from other living things— 

 and from the doings and intrusions of man. 



Ill 



