viii PREFACE TO THE FIRST EDITION. 



with the general principles of science, has not the skill to apply 

 them to each particular case, it is to be feared that no disquisi- 

 tion, however elaborate, would enable him to do so. So far has 

 it been from my intention to enter into subordinate details, 

 that I have carefully avoided them, from a fear of complicating 

 the subject, and making that obscure which in itself is suffici- 

 ently clear. All that a physiologist has reaUy to do with 

 Horticulture is, to explain the general nature of the Yital 

 actions of a plant, and the manner in which these are commonly 

 applied to the arts of cultivation ; if he quits this ground, he 

 extends his limits so much that there is no longer a horizon in 

 view. No one, indeed, could advantageously investigate the 

 minor points of cultivation in aU their branches, unless he 

 were both a good physiologist and a practical gardener of the 

 greatest experience, a combination of qualifications which no 

 man has ever yet possessed, and to which I, most assuredly, 

 have not the shadow of pretension. 



In conclusion, let me, in impressing upon the minds of gar- 

 deners the importance of attending to first principles, also 

 caution them against attempting to apply them, except in a 

 limited manner, and by way of safe experiment, until they fully 

 understand them. The difference between failure and success, 

 in practice, usually depends upon slight circumstances, very 

 easily overlooked, and not to be anticipated beforehand, even 

 by the most skilful ; their importance is often unsuspected till 

 an experiment has failed, and may not be discovered tUl after 

 many unsuccessful attempts, during which more mischief may 

 be done by extensive failures than the result is worth when 

 attained. No man understood this better than the late 

 Mr. Knight, the best horticultural physiologist that the world 

 has seen, whose experiments were conducted with a skiU and 

 knowledge which few can' hope to equal. So fuUy was he aware 

 of the uncertain issue of experimental investigations in Horti- 



