210 CONSERVATIVE ORGANS. [LECT. V. 



from the soil the materials fitted for the nourish- 

 ment and support of the vegetable body. 



It is a wise provision of nature, that as plants 

 are not endued with volition and extensive loco- 

 motion, nor guided by instinct nor reason, they 

 are subject to more regular and unalterable 

 laws than the animal creation, at least than that 

 portion of it which possesses those functions which 

 have just been enumerated : their food is always 

 placed within their reach, and they enjoy good 

 health and arrive at perfection in their growth, in- 

 dependent of external accidents to which animals 

 are equally liable, when they are situated where 

 the soil contains those principles which are best 

 adapted for the various purposes of their economy. 

 The consideration of this fact suggests the ques- 

 tions, What is the composition of soils ? What 

 part of soils is taken up as food by the roots of 

 plants ? To answer them has long employed the 

 attention of the philosophical observer, and many 

 and very various opinions have been given to the 

 public ; but it is only since modern chymistry 

 made those discoveries which may justly be re- 

 garded as the most splendid triumphs of experi- 

 mental Science, that any thing rational and satis- 

 factory has been advanced. I will endeavour to 

 lay before you as clear a view as I am able of the 

 most probable conclusions which may be drawn 

 from these opinions ; and, in raising one corner of 



