PREFACE. 



the supplying, in a natural manner, as far as possible, 

 all the conditions which are necessary to the nutrition 

 and perpetuation of plants ; and, that it is within the 

 open pathway of Science, and not the bye-ways of em- 

 piricism, that the finger-post of direction should be 

 sought, 



Royal Botanic Garden, Regent's Park, 

 March 2nd, 1844. 



TO THE SECOND EDITION. 



IN the present edition, it has been thought best to 

 preserve the original text exactly as it appeared in the 

 first edition. The new matter will be found in the 

 Appendix. 



The author may take this opportunity of returning 

 his thanks to those who have noticed and commended 

 the former edition, and of expressing a hope that the 

 present will receive an equal share of favour. 



Camden Town, Aug. 1, 1847. 



