CONTENTS 



CHAPTER 



FOREWORD TO TEACHERS ....... 7 



I. SOME REASONS FOR THE STUDY OF BIOLOGY. ... 15 



II. THE ENVIRONMENT OF PLANTS AND ANIMALS ... 19 



III. THE INTERRELATIONS OF PLANTS AND ANIMALS . . 28 



IV. THE FUNCTIONS AND COMPOSITION OF LIVING THINGS . 47 

 V. PLANT GROWTH AND NUTRITION THE CAUSES OF GROWTH 58 



VI. THE ORGANS OF NUTRITION IN PLANTS THE SOIL AND 



ITS RELATION TO ROOTS , ..... 71 



VII. PLANT GROWTH AND NUTRITION PLANTS MAKE FOOD . 84 

 VIII. PLANT GROWTH AND NUTRITION THE CIRCULATION AND 



FINAL USES OF FOOD BY PLANTS .... 97 



IX. OUR FORESTS, THEIR USES AND THE NECESSITY OF THEIR 



PROTECTION ......... 105 



X. THE ECONOMIC RELATION OF GREEN PLANTS TO MAN . 117 

 XL PLANTS WITHOUT CHLOROPHYLL IN THEIR RELATION TO 



MAN ........... 130 



XII. THE RELATIONS OF PLANTS TO ANIMALS .... 159 



XIII. SINGLE-CELLED ANIMALS CONSIDERED AS ORGANISMS . 166 



XIV. DIVISION OF LABOR, THE VARIOUS FORMS OF PLANTS AND 



ANIMALS .......... 173 



XV. THE ECONOMIC IMPORTANCE OF ANIMALS .... 197 



XVI. AN INTRODUCTORY STUDY OF VERTEBRATES . . . 232 



XVII. HEREDITY, VARIATION, PLANT AND ANIMAL BREEDING . 249 



XVIII. THE HUMAN MACHINE AND ITS NEEDS .... 266 



XIX. FOODS AND DIETARIES ........ 272 



XX. DIGESTION AND ABSORPTION. ...... 296 



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