CHAPTER XII

SUMMARY AND CONCLUSIONS 285

Disharmonies in the human constitution as the chief source of our sorrows—Scientific data as to the origin and destiny of man—The goal of human existence—Difficulties in the way of scientific investigation of the problem, What is progress?—Difficulty of including the whole human rate in a scheme of progress and morality—The instincts of life and of natural death—Application to real life of the doctrines set forth in this book

ILLUSTRATIONS

Photograph of Élie Metchnikoff _Frontispiece_ _Figs._ _Page_ 1. _Catasetum saccatum_ 24 2. _Herminium monorchis_ 26 3. _Cerceris_ 28 4. _Listera ovata_ 32 5. _Pelopæus_ 34 6. Cæcum and vermiform appendage of man 44 7. Cæcum and vermiform appendage of chimpanzee 45 8. Fœtus of gibbon 46 9. Human fœtus 47 10. Fœtus of gorilla 50 11. Human fœtus 51 12. _Paramecium_ about to divide 230 13. Conjugation of _Paramecia_ 231 14. Section of a renal tubule invaded by Macrophags 241 15. Brain cells devoured by Macrophags 241 16. Hair becoming grey 243 17. _Chætogaster_ about to divide 265 18. Ephemerids 271 19. Swarms of _Palingenia virgo_ 273 20. Larva of an Ephemerid 276

THE NATURE OF MAN

PART I DISHARMONIES IN THE NATURE OF MAN