Two books stand out from the pedagogical standpoint as by far the most helpful of their kind on the market. No teacher of botany or zoology can afford to be without them. They are: Lloyd and Bigelow, _The Teaching of Biology_, Longmans, Green, and Company, and C. F. Hodge, _Nature Study and Life_, Ginn and Company. Other books of value from the teacher's standpoint are: Ganong, _The Teaching Botanist_, The Macmillan Company; L. H. Bailey, _The Nature Study Idea_, Doubleday, Page, and Company; and McMurry's _How to Study_, Houghton Mifflin Company. CONTENTS CHAPTER 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 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 XXI. THE BLOOD AND ITS CIRCULATION 313 XXII. RESPIRATION AND EXCRETION 329 XXIII. BODY CONTROL AND HABIT FORMATION 348 XXIV. MAN'S IMPROVEMENT OF HIS ENVIRONMENT 373 XXV. SOME GREAT NAMES IN BIOLOGY 398 APPENDIX 407 SUGGESTED COURSE WITH TIME ALLOTMENT AND SEQUENCE OF TOPICS FOR COURSE BEGINNING IN FALL 407