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capable of being raised without manure. This cele- 

 brated horticulturist lived, however, sufficiently long 

 to alter his opinion. The results of his later and 

 most refined observations led him to the conclusion, 

 that no single material afforded the food of plants. 

 The general experience of farmers had long before 

 convinced the unprejudiced of the truth of the same 

 opinion, and that manures were absolutely consumed 

 in the process of vegetation. The exhaustion of soils 

 by carrying off corn crops from them, and the effects 

 of feeding cattle on lands, and of preserving their 

 manure, offer familiar illustrations of the principle ; 

 and several philosophical enquirers, particularly Has- 

 senfratz and Saussure, have shewn by satisfactory ex- 

 periments, that animal and vegetable matters deposit- 

 ed in soils are absorbed by plants, and become a part 

 of their organized matter. But though neither water, 

 nor air, nor earth, supplies the whole of the food of 

 plants, yet they all operate in the process of vegeta- 

 tion. The soil is the laboratory in which the food is 

 prepared. No manure can be taken up by the roots 

 of plants unless water is present ; and water or its 

 elements exist in all the products of vegetation. The 

 germination of seeds does not take place without the 

 presence of air or oxygene gas ; and in the sunshine 

 vegetables decompose the carbonic acid gas of the at- 

 mosphere, the carbon of which is absorbed, and be- 

 comes a part of their organized matter, and the oxy- 

 gene gas, the other constituent, is given off; and in 

 consequence of a variety of agencies, the ceconomy of 

 vegetation is made subservient to the general order of 

 the system of nature. 



