6 Contents 



CHAPTER PAGE 



III. THE ABSORPTION OF NITROGEN AND THE CON- 



STRUCTION OF NITROGENOUS SUBSTANCE . 323 



IV. THE PROGRESS OF OUR KNOWLEDGE OF THE 



R6LE OF THE CONSTITUENTS OF THE ASH OF 

 PLANTS 357 



V. THE DISCOVERY OF CHEMOSYNTHESIS . . 368 



VI. THE DEVELOPMENT OF KNOWLEDGE OF THE 



METABOLIC PROCESSES 372 



VII. THE DEVELOPMENT OF KNOWLEDGE OF THE 

 METABOLIC PROCESSES (continued) : DIGES- 

 TION. THE NATURE OF NUTRITION . . 400 



VIII. THE DEVELOPMENT OF THE MODERN IDEA OF 

 THE CATABOLIC PROCESSES AND THE INTERNAL 

 ENERGY RELATIONS OF PLANTS . . . 419 



IX. THE INFLUENCE OF THE STUDY OF THE NUTRI- 

 TION OF HETEROTROPHIC PLANTS ON THE 

 PROGRESS OF KNOWLEDGE OF THE TRUE 

 NATURE OF THE FOOD OF PLANTS . . .431 



X. THE PROBLEMS OF GROWTH AND ITS ASSOCIATED 



CONDITIONS 442 



XI. THE DEVELOPMENT OF THE THEORY OF SPECIAL 

 SENSITIVENESS UNDER THE INFLUENCE OF 

 THE 'ORIGIN OF SPECIES' .... 458 



GENERAL CONCLUSION . . . . . . 501 



BIBLIOGRAPHY .... . 508 



INDEX 539 



