vi PREFACE TO THE FIRST EDITION. 



other things ; and so arranged that the intimate connexion of 

 one branch of practice with another, and of the whole with a 

 few well ascertained facts upon which everything else depends, 

 may be distinctly perceived from a single point of view. The 

 admirable papers of Mr. Knight are scattered through the 

 Horticultwal Transactions ; and the writings of other physi- 

 ologists are dispersed through so many different works, that 

 the labour of finding them, when wanted, is greater than is 

 willingly undertaken even by those who have access to ample 

 libraries. With regard to general works on Horticulture, it is 

 very far from my wish to say one word in disparagement of the 

 many excellent publications upon this subject which have 

 already appeared in this country 5 on the contrary, the 

 improved state of gardening among us may be reasonably 

 ascribed to the influence of some of these valuable works : but 

 it must be admitted that the true principles of physiology are 

 not, in such books, so separated from the details of routine on 

 the one hand, or so applied to them on the other, as to be 

 readily understood by those who want either the skill or the 

 inclination to distiuguish empirical directions from rules which 

 are plainly founded upon the very nature of things. I must 

 also be permitted to observe that, although results are correctly 

 stated in such books, they are not unfrequently referred to 

 wrong causes. 



In preparing the following pages for the press, my anxious 

 desire has been to strike out all unnecessary matter, even 

 although it may be required to complete the physiological 

 explanation of common facts ; and to introduce little beyond 

 that which every gardener can verify for himself. Vegetable 

 anatomy is no doubt the foundation of all correct views of 

 physiological action ; chemistry is of the first importance, when 

 the general functions of plants are considered in a large and 

 general way ; and electricity probably exercises an important 



