CONTENTS 



204 



210 



227 

 239 



CHAP. PAGE 



XV. LAND FORMS OF WATER PLANTS, AND THE EFFECT 



OF WATER UPON LAND PLANTS . 

 XVI. THE ROOTS OF WATER PLANTS 

 XVII. THE VEGETATIVE REPRODUCTION AND WINTERING 

 OF WATER PLANTS ..... 

 XVIII. THE FLOWERS OF WATER PLANTS AND THEIR RELA- 

 TION TO THE ENVIRONMENT 



XIX. THE FRUITS, SEEDS AND SEEDLINGS OF WATER 

 PLANTS ........ 



PART III 



THE PHYSIOLOGICAL CONDITIONS OF PLANT LIFE 



IN WATER 

 XX. GASEOUS EXCHANGE IN WATER PLANTS . . 253 



XXI. ABSORPTION OF WATER AND TRANSPIRATION 



CURRENT IN HYDROPHYTES .... 260 



XXII. THE INFLUENCE OF CERTAIN PHYSICAL FACTORS IN 



THE LIFE OF WATER PLANTS . . .273 



XXIII. THE ECOLOGY OF WATER PLANTS . . . 285 



PART IV 



THE STUDY OF WATER PLANTS FROM THE PHYLOGENETIC 

 AND EVOLUTIONARY STANDPOINTS 



XXIV. THE DISPERSAL AND GEOGRAPHICAL DISTRIBUTION 



OF WATER PLANTS ..... 295 



XXV. THE AFFINITIES OF WATER PLANTS AND THEIR 

 SYSTEMATIC DISTRIBUTION AMONG THE ANGIO- 

 SPERMS ....... 308 



(i) The Affinities of Certain Aquatic Angio- 



sperms . . . . . 308 



(ii) Theoretical Considerations . . . 317 

 XXVI. THE THEORY OF THE AQUATIC ORIGIN OF MONO- 

 COTYLEDONS ...... 322 



XXVII. WATER PLANTS AND THE THEORY OF NATURAL 

 SELECTION, WITH SPECIAL REFERENCE TO THE 



PODOSTEMACEAE ..... 



XXVIII. WATER PLANTS AND THE 'LAW OF Loss' IN 

 EVOLUTION 



327 

 336 



BIBLIOGRAPHY 



INDEX TO BIBLIOGRAPHY 



INDEX 



349 

 415 

 422 



