XIV CONTENTS. 



CHAPTER PAGE 



XIX. CoLorKS OF Flowers ... ... ... ... 174 



XX. The Emergence of the Floral Whorls ... 184 



XXI. The Development of the Floral Whorls ... 191 



XXII. Heterogamy and Autogamy ... ... ... 198 



XXIII. Heterostylism ... ... ... ... ... 208 



XXIV. Partial Diclinism ... ... ... ... 220 



XXV. Sexuality AND THE Environment ... ... ... 230 



XXVI. Degeneracy of Flowers ... ... ... 2.51 



XXVII. Degeneracy of F LO^fEHS— Continued ... ... 273 



XXVIII. Progressive Metamorphoses ... ... ... 285 



XXIX. Eetrogressive Metamorphoses ... ... ... 295 



XXX. Phyllody of the Floral Whorls ... ... 301 



XXXI. The Varieties of Fertilisation ... ... ... 311 



XXXII. Fertilisation and the Origin of Species ... 329 



