196 THE CANADIAN NATURALIST. [June, 



Many, indeed, in the excess of their disappointment, were led to 

 repudiate the "mineral theory " itself, and to impugn all scientific 

 husbandry as a dangerous delusion. 



It is now easy, and also in the highest degree instructive, to 

 trace this error of the illustrious philosopher to its source in the 

 then state of science. The special discovery, which has rendered 

 impossible the recurrence of such an error, may also now be 

 pointed out ; and this is, in itself, of so much interest and impor- 

 tance that it deserves our most careful attention. 



Early View of the Ingestion of Cinereal Aliment. 

 — At the date of Liebig's patent it was universally believed that 

 the ash-constituents of plants were supplied to the roots in moving 

 aqueous solution ; i. e., in solutions permeating the soil unchanged, 

 and meeting in its passage rootlet after rootlet, so that the tender 

 gpongioles, being immersed therein, could drink. According to 

 this view, it was not the roots which travelled to the ash-constitu- 

 ents, but the ash-constituents which were carried, in solution, to 

 the roots. This belief led Liebig to fear that the more soluble 

 alkaline ingredients of his manure would, by the rain falling on 

 the land, be washed away from the other ingredients, and thus 

 separated therefrom. He therefore directed his mixture to be 

 treated " iu such a manner that the character of the alkaline 

 matters may be changed, and the same rendered less soluble" ; and 

 he indicated, as the best mode of effecting this object, the fusion 

 of the materials In a reverheratory furnace. The danger feared 

 by Liebig was, we now know, illusory ; and the treatment he 

 adopted to avert the supposed evil was such as to render his 

 mixture corupara lively inert. It was reserved for an English 

 chemist, John Thomas Way, to make, some five years later, the 

 important investigation which led to the abandonment of the 

 above-stated opinion as to the conveyance of liquid plant-food to 

 the roots, and introduced in its stead an entirely new view of the 

 distributive mechanism of the soil. 



Absorptive Power op Soils. — ^Way's observation, briefly 

 stated, was thai ooils possess an absorptive power, in virtue of 

 which they withdraw from aqueous solutions of saline plant-food 

 filtered through them, sometimes the whole, sometimes the base 

 only, of the dissolved salt. He found that, in the latter case, the 

 acid of the salt from which the soil had thus withdrawn the base, 

 passed through the soil in combination with lime. By a well- 



