CONTENTS 



CHAPTER PAGE 



1. THE PHYSICAL UNIVERSE . i 



2. THE LIVING SUBSTANCE 5 



3. THE CELL AND ITS ACTIVITIES . . 13 



4. THE TISSUES 



5. RESPIRATION ... 3 1 



6. THE INDIVIDUAL . . -37 



7. MENDELISM .... 4 1 

 8.' THE RED SUNFLOWER . 5 1 

 9. THE CHROMOSOMES .... .62 



10. FERTILIZATION ... -73 



11. SEX 77 



12. NATURE AND NURTURE . 89 



13. SOCIAL LIFE . -94 



14. CHARLES DARWIN ii 



15. VARIATION . n 5 



16. ALCOHOL AND HEREDITY . .120 



17. NATURAL SELECTION ... .129 



18. ARGUMENTS FOR EVOLUTION . 137 



19. THE HISTORY OF LIFE 144 



20. THE FLORISSANT SHALES OF COLORADO . . 157 



21. CAROLUS LINNAEUS . . .164 



22. THE PRINCIPLES OF CLASSIFICATION . . 175 



23. THE PHYLA OF ANIMALS ..... .178 



24. PROTOZOA ...... .186 



25. PROTOZOA AND HEREDITY .... 194 



26. PROTOZOA AND DISEASE .... 199 



27. SPONGES ..... 207 



28. CCELENTERATA ..... . 2IO 



29. ECHINODERMATA ...... 2l8 



30. BRYOZOA ....... 226 



31. PLATYHELMINTHES ... 229 



32. NEMERTINEA, NEMATHELMINTHES, AND ROTATORIA . . 233 



33. ANNELID WORMS ..... 237 



34. MOLLUSCA .... 243 



35. ARTHROPODA (GENERAL) ... . 253 



vii 



