198 THE CANADIAN NATURALIST. [June, 



therefore are, in a double sense, " genial" ; firstly, as liberating 

 within the soil a fresh supply of surface-held plant-food, available 

 for the rootlets to touch and take ; secondly, as promoting the 

 growth of the rootlets, and so moving forward thousands of spon- 

 gioles simultaneously into contact with fresh food-holding sur- 

 faces. 



These beautiful relations of the soil, the food, and the roots, 

 now that they are discovered, are perceived to be so indispensable, 

 that . one almost wonders they were not arrived at by a j^riori 

 reasoning. For, had soils been undefended by this absoi-ptive 

 property, the rainfall of centuries passing through them must 

 have, ages ago, washed away every trace of their soluble salts. 

 Subsoil drainage, so far from tending, as it does, to fertilize land, 

 would but have exposed its sandy remnants to a lixiviating process 

 more rapid and exhausting than even that of the natural filtration. 



Distributive Mechanisai of Soils. — It does not of course 

 fall within the scope of the present rapid sketch, to trace this 

 newly-discovered property of soils, to all its important conse- 

 quences. As one example, perhaps the most striking, of these, 

 the reporter would single out the admirable distributive influence 

 of the absorptive power ; which (counteracting in this respect the 

 force of gravitation) tends to maintain the nutritive ingredients 

 where they are most needed, i. e., in the upper layers of the soil, 

 leaving the surplus only to be deposited, as in a reservoir, in the 

 layers beneath. Each layer, in fact, when saturated itself, lets 

 pass unchanged the surplus solution, to saturate the layer next 

 below ; and so on, in progression, through the whole depth of the 

 ■cultivable soil. 



Keverting, with this property of soils before us, to Liebig's 

 patented manure, we see clearly the cause of its failure. In aiming 

 at its improvement by the reduction of its solubility, the illustrious 

 inventor inadvertently placed himself in opposition to a law of 

 nature. How nobly he retrieved this error will presently appear. 



Distributive Mechanism of Farm-yard Dung. — 3Iean- 

 while, it is a point worth notice, that an error, similar to Liebig's, 

 is apt to vitiate experimental comparisons between the immediate 

 fertilizing efiect of farm yard dung, and that of the ash obtained 

 by its incineration. The inferiority of the ash to the dung itself, 

 -as an immediate fertilizer, is commonly ascribed solely to the dis- 

 .sipation by fire of the volatile constituents of dung, and particularly 



