THE ADAPTATION OF THE PLANT TO THE SOIL. 



7 



ties become apparent. In the first place, all plants show much the 

 same composition as regards the substances they derive from the soil; 

 if we ignore the carbon which a plant obtains from the atmosphere 

 the other elements present are restricted in number and are identical 

 in all plants. 



Table I. will illustrate the fact that variations in the composition 

 of the ash of the same plant grown under different circumstances 



,5% — 



J2S 



10 



7-5 



6 



2-5 



^lot 3 4-18 7 5 17 4-2 9 II 14 



Fig. 6. — Percentage of Trifolium repens, T. pratense, and Lotus 

 corniculatus taken together. 

 For manuring, see fig. 5. 



are of the same order as the differences in the composition of the ash 

 of very distinct plants given in Table II. (see p. 9). 



It has been the custom to draw distinctions between silica plants 

 like cereals, the ash of which contains a good deal of silica, lime plants 

 like clover, and potash plants like some of the root-crops ; but these, 

 distinctions break down on experiment, for it is not found to be neces- 

 sary or even beneficial to give any of these plants a special dose of its 

 characteristic constituent. . . ■ ■ 



