XI. 



FOOD FROM THE SOIL 



It is but a very small part of their food after all which 

 plants, generally speaking, draw from the mineral 

 matter of the soil in which they grow ; and yet this 

 small quantity is not merely important, but absolutely 

 necessary. It is dissolved by water and gases, and by 

 the action of the plant itself, and is then taken up by 

 the roots, especially the younger, finer roots, and root- 

 hairs, by which it is passed on to the stem, and so is 

 conveyed to every part, not only to branches, leaves, 

 and buds, but also to flowers and fruit. Every part 

 of a plant needs some amount of mineral matter, and 

 the plant cannot obtain it without water, for whether 

 dissolved by the plant's roots or otherwise, it is in each 

 case taken up in a very diluted condition ; so diluted, 

 indeed, that the water containing it is hardly to be dis- 

 tinguished from ordinary drinking-water. 



The plant could not be sufficiently nourished by 

 these very weak dilutions, especially while it is growing, 

 but for the fact that it is constantly receiving them. 



Perhaps one of the most striking examples of the way 

 in which plants are fed by this very weak food is to be 

 found among the sea-weeds. Many sea-weeds contain 



