46 THE PLANT. 



form cellulose in the leaves, roots, and stems ; and the 

 proportion of the unazotised to the nitrogenous matter 

 was altered. In the plant growing in water, there was a 

 constant decrease of unazotised matter ; while in the 

 other a certain quantity of that substance was generated 

 anew. Nothinsj can be more certain than that in Bous- 

 singault's experiments, the first-formed leaves acquired by 

 the supply of mineral substances the faculty of absorbing 

 and decomposing carbonic acid, a power not possessed by 

 the plant developed in pure water; and that as much 

 soluble unazotised substance was reproduced as had been 

 consumed in the formation of the leaves and roots, by the 

 conversion into cellulose of the store originally present. 



In the movable constituents of the plant, the relative 

 proportion between the unazotised and the azotised seed 

 constituents was manifestly restored pretty nearly as it 

 existed in the seed ; both matters passed through the 

 stem into every new formed leaf-bud, and took part in the 

 developement of new leaves, by whose operation the con- 

 sumption of unazotised matter was always made good 

 again within a certain limit, so that the same process 

 could be repeated again and again for months. In every 

 one of the dead leaves (and root fibres) a certain quantity 

 of the azotised substance remained behind, and in the last 

 period of vegetation the floating remainder of this sub- 

 stance was collected in the pod and the seeds. 



The supply of mineral substances had served to effect 

 the continuance of the chemical process, and caused the 

 production of unazotised substances. By the presence of 

 these mineral bodies, and by the cooperation of the azo- 

 tised matters, new material was engendered fi^om carbonic 

 acid to form the cell-walls, and the term of life was pro- 

 longed to its proper hmit. The most remarkable point 

 is, that a quantity, comparatively so smaU, of azotised 



