CONTENTS 



CHAPTER PAGE 



I. SOME REASONS FOR THE STUDY OF BIOLOGY . . .13 



II. THE SURROUNDINGS OR ENVIRONMENT OF LIVING THINGS 17 



III. THE FUNCTIONS AND COMPOSITION OF LIVING THINGS 26 



IV. FLOWERS AND THEIR WORK .... 34 

 V. FRUITS AND THEIR USES 51 



VI. SEEDS AND SEEDLINGS 65 



VII. ROOTS AND THEIR WORK 84 



VIII. THE STRUCTURE AND WORK OF THE STEM ... 98 



IX. LEAVES AND THEIR WORK ...... 115 



X. OUR FORESTS ; THEIR USES AND THE NECESSITY FOR 



THEIR PROTECTION 133 



XI. THE VARIOUS FORMS OF PLANTS AND HOW THEY REPRO- 

 DUCE THEMSELVES ....... 144 



XII. How PLANTS ARE MODIFIED BY THEIR SURROUNDINGS . 159 



XIII. How PLANTS BENEFIT AND HARM MANKIND . . . 170 



XIV. THE RELATIONS OF PLANTS TO ANIMALS . . . 184 

 XV. THE PROTOZOA 190 



XVI. THE METAZOA DIVISION OF LABOR .... 199 

 XVII. THE WORMS, A STUDY OF RELATIONS TO ENVIRON- 

 MENT 212 



XVIII. THE CRAYFISH. A STUDY OF ADAPTATIONS . . . 221 



XIX. THE INSECTS 233 



XX. GENERAL CONSIDERATIONS FROM THE STUDY OF INSECTS 249 



XXI. THE MOLLUSKS 267 



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