CHAPTER I 



THE DEVELOPMENT OF KNOWLEDGE OF THE 

 PROCESSES OF ABSORPTION OF WATER AND 

 ITS SUBSEQUENT TRANSPORT IN THE BODY 

 OF THE GREEN PLANT 



THE mechanisms of the water supply derived from the 

 soil and the functions which are associated with it were 

 the subject of prolonged and exhaustive inquiry during 

 the last half of the nineteenth century, as a result of 

 which an important change came over the minds of veget- 

 able physiologists. The older mechanical ideas, which were 

 advanced by Dutrochet and his successors, and which then 

 marked a distinct advance in thought, were gradually 

 undermined by experiment and discussion, and the proba- 

 bility that the plant itself as a living organism has the 

 largest share in the regulation of the processes of absorp- 

 tion and distribution began to make itself felt. It was not 

 until recently that such views were in any great favour ; 

 what was called the selective power of the roots was ad- 

 vanced only tentatively, and was strongly opposed by most 

 physiologists, who preferred to base their opinions on 

 mechanical conceptions of the methods of osmosis and 

 other purely physical processes. To them the plant was 

 a machine, and, like the machines of the commercial 

 world, it had no power apart from the physical forces 

 active in its environment. 



The problem which presents itself now for discussion lies 

 at the root of the nutritive processes of plants. It includes 

 the methods of the absorption of water from the soil, 

 the acquirement of the mineral constituents of the latter, 



