SECOND REPLY. 173 



the wise care of Nature united these matters at once in 

 plants, which in exactly the same determinate combination, 

 are afterwards to be applied to the use of animals. 



But natural science must not stop at such teleological 

 considerations ; and it next becomes our object to demon- 

 strate that those inorganic salts have a perfectly definite 

 importance to the plant itself. Nay, even if we are not yet 

 in a position to afford this demonstration, we must still, 

 from the constant occurrence of determinate mineral con- 

 stituents in determinate plants, conclude their necessity to 

 the existence and well-being of the plant, as Theodore de 

 Saussure was the first to do, in his immortal " Recherches 

 sur la Vegetation." Supported by these views, Liebig now 

 states : That since the organic nutriment stands every- 

 where in equal abundance at the service of all plants, the 

 cause of the great difference of vegetation cannot be sought 

 therein, consequently it must lie in the inorganic consti- 

 tuents, and it is essentially indifferent whether we convey 

 manure to the field, or burn it first and strew the ashes on 

 the soil, since its efficacy is dependant solely on the consti- 

 tuents of the ashes. 



It is easy to see that this principle, applied to agricul- 

 ture, suddenly throws a new, bright light over all those 

 phenomena, to explain which man formerly wearied him- 

 self in vain. Now, we can easily conceive why an irrigated 

 meadow can annually yield a large quantity of hay, without 

 manure, since the necessary quantity of salts are brought 

 to it by the spring water. It becomes clear how the 

 Peruvian may obtain a luxuriant harvest of Maize on the 

 arid sand-drift, if but a little rill brings it the needful 

 soluble earth-salts from the snowy peaks of the Andes. 

 Hundreds of similar phenomena are at once explained by 

 this ingenious idea of Liebig ; but hundreds of new ideas 



