228 BASIS OF ENLIGHTENED PRACTICAL AGRICULTURE. 



2°. That we must seek for these necessary substances in the inorganic 

 constituents which are present in the richest crops of every kind — in the 

 produce of the most fertile soils.* 



3°. That where these necessary substances are not jjresent in any 

 soil, we may infer that it will prove unfit to yield a luxuriant crop of a 

 given kind ; or, on the other hand, where these substances are not to be 

 detected in the ash of the plant, that thefault of the crop, if any, maybe 

 ascribed to their partial or total absence from the soil on which it grew. 



These conclusions form the basis of an enlightened and scientific prac- 

 tical agriculture. This basis, however, requires to be strengthened and 

 enlarged by further experimental investigations. 



• "I have examined," says Sprengel, "the finest seed-corns from many localities, and I 

 have invariably found the quantities not only of the organic substances— starch, sugar, &c.— 

 but also of the inorganic compounds in all the celebrated seed-corns, so perfectly alike, that 

 one would have thought they had all grown on one and the same soil."— i^Are vom Diingtr^ 

 p. 43. 



