INTRODUOTION. 19 



rions of particular theories relative to growth, structure, 

 food of plants, or any of the various points in vegetable 

 physiology which are considered debatable questions. 

 But as I shall have occasion in the following pages to ad- 

 vise deep and thoroughly pulverized soil, I have stated 

 the foregoing simple facts, so that the reader may under- 

 stand why they are recommended. 



