CONTENTS. 



CHAPTER I. 



PAr^E 

 THE ORIGIN OF PETALS j 



CHAPTER II. 



GENERAL LAW OF FROGRF.SSIVE COLOURATION 17 



CHAPTER III. 



VARIEGATION 



CHAPTER IV. 



RELAPSE AND RETROGRESSION . . . 



61 



71 



CHAPTER V. 



DEGENERATION 



91 



CHAPTER VI. 



MISCELLANEOUS .... 



IIO 



