LECT. V.j THE ROOT. SOILS. 223 



stances; but these also yield salts which prove 

 highly stimulating to growing plants ; and although 

 plants seem to attain great bulk and vigour when 

 much manure is applied, yet they are over-sti- 

 mulated, and their growth is connected with dis- 

 ease, in the same manner as in an overfed and 

 pampered animal. The natural state of both is 

 altered; premature age succeeds, and death ar- 

 rives long before the period when he should be 

 naturally expected. Those plants also which are 

 intended for the food of man and animals, when 

 reared upon soil of the kind we are now noticing, 

 yield less nutriment in the same bulk than that 

 which more healthy plants yield, and it is also of 

 an unwholesome kind. Upon the whole, we may 

 truly assert that more harm is done by loading 

 soils artificially with much animal and vegetable 

 matter, than the natural deficiency of it in soils 

 can occasion. 



Such are the most general components of al- 

 most all soils ; and as it is of much importance to 

 know what is the composition of any soil, either 

 in order to ascertain the probable causes of its 

 fertility, with the view that less fertile soils may be 

 rendered similar to it ; or to estimate the value of 

 ground with which we are unacquainted, and on 

 which we have no opportunity of making experi- 

 ments by rearing plants ; we will endeavour to 

 point out how this can be done. 



