PLANTS GROWN IN SOIL AND IN WATKR. 10;j 



adapted to tlic requirements of plants, and how mucli 

 liinnan ingenuity, knowledge, and minute care, it takes to 

 supply, under cii'cumstances differing so Avidely from the 

 natural condition, certain properties of arable soil, which 

 insure the healthy growth of plants. 



K the supply of nutritive substances in a state of solu- 

 tion were really suited to the nature of the plant and 

 the functions of the roots, it would follow that in such a 

 solution, most abundantly provided with all the elements 

 of food in the most movable form, plants must thrive 

 the more luxuriantly the fewer the obstacles are which 

 oppose their absorption of food. 



A young rye-plant, placed in a fertile soil, will often 

 send forth a bunch of thirty or forty stalks, each of them 

 bearing an ear, and will j^eld a thousandfold crop of 

 grauis, or even more ; yet this plant draws its mineral food 

 from a volume of earth, from which the most persevering 

 lixiviation with pure water, or water containing carbonic 

 acid, will not extract even the one-hundredth part of the 

 phosphoric acid and nitrogen, nor the fiftieth part of 

 the potash and the sihcic acid, which the plant has drau^i 

 from the soil. How is it then possible, under such cir- 

 cumstances, to assume that water alone would have suf- 

 ficed, by virtue of its solvent power, to render available 

 to the plant all the substances found in it ? 



None of the plants grown in watery solutions of the 

 mineral elements of their food, even though thriving 

 luxuriantly, will bear the remotest comi)arison, in the bulk 

 of vegetable matter produced, with plants grown in a 

 fertile soil ; and the entire process of developement in them 

 proves that the conditions of thriving growth in the soil 

 are quite of another kind. 



The greatest weight of crop obtained by Stohmaiin 

 from an Lidian corn plant grown in water amounted to 



