CONTENTS 



PAGE 



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 

 XI. 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 

 XTV. 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 . . . t . 296 



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