PREFACE 



The report of the National Education Association committee 

 on the "Reorganization of Science in Secondary Schools" lays 

 down the principle of a synthetic treatment of biology. In some 

 quarters the change appears to have gone no farther than the 

 substitution of ''plant biology" for botany, ''animal biology" 

 for zoology, and so on. The present book assumes that the 

 tendency toward a unified treatment of more comprehensive 

 principles, which rs paralleled in other departments of instruc- 

 tion, represents the most fruitful adjustment of schooling to 

 the rapidly growing body of scientific knowledge. 



It takes account further of another tendency in our current 

 life, namely, the rapid extension of secondary-school opportuni- 

 ties to new population groups. The high schools now receive 

 increasing numbers of boys and girls whose interests and aspira- 

 tions are radically different from those of earlier generations 

 of pupils. The high school is no longer primarily or chiefly a 

 college-preparatory institution. More and more of our students 

 are concerned with the concrete and the practical rather than 

 with the abstract and theoretical. Boys and girls who look for- 

 ward to an early entrance upon occupational activities and the 

 responsibilities of earning and spending money have as much 

 need for the study of biology as have those who plan to go to 

 college or the professional schools. Even among these last there 

 are very many for whom the subject can be most interestingly 

 and most profitably developed in terms of our everyday affairs 

 rather than in terms of academic analysis. 



The division of this book into three main parts ("Getting 

 Acquainted with Life," "Biology of Health," and "Biology of 

 Wealth") is intended to emphasize applications of science to 

 human affairs, and at the same time to suggest that we have to 

 get knowledge before we can apply it. Each chapter is preceded 



