12 THE GEAPE. 



any comparison between them and the constituents 

 of the soil, because these are seldom specified in the 

 forms in which they are directly conveyed to the 

 plant, that is, in a soluble state. "When in a soil 

 substances exist in such a state of combination that 

 they only become fit for use by exposure to the air for 

 some time, then such a soil will nourish the plant in 

 the long run, but is not generally in a condition to do 

 so without the assistance of inorganic manure. Tor 

 the rest I feel myself more at liberty to pass over the 

 chemical composition of the soil, because I have never 

 yet found any mention of the chemical composition of 

 the incombustible manure of the vine. 



