CONTENTS xi 



CHAPTER XVII 



PAGE 



THE MYSTERY OF THE CELL . . . . .335 



CHAPTER XVIII 



THE ELEMENTS AND WATER, IN RELATION TO THE LIFE- 

 WORLD . . . . . . .355 



CHAPTER XIX 



Is NATURE CRUEL? THE PURPOSE AND LIMITATIONS OF 



PAIN . . . . . . 369 



CHAPTER XX 



INFINITE VARIETY THE LAW OF THE UNIVERSE CONCLU- 

 SION .. . . . . . .385 



INDEX . . . . . .401 



