GENERAL IDEA. 



231 



ficial space^ that is^ on space of two diinensions_, as it is 

 technically called. Any one who studies the interesting 

 indications of "position/^ appended by Dr. Lindley to 

 each of his natural orders_, will readily perceive the diffi- 

 culties which exist in this quarter. Some have thought 

 that a perfect co-ordination of affinities can be made 

 only on space of three dimensions, as^ for example^ in 

 the manner the stars are distributed in the firmament. 

 We cannot pursue this subject, which would lead us into 

 the most profound depths of the science of botany ; and 

 indeed we need not enter into it^ as in the actual forma- 

 tion of an arboretum we are compelled to work on sur- 

 faces. Let it be remembered^ then, that both on account 

 of the fragmentary nature of the materials employed, 

 and their numerous and intertwining relations, as well 

 as the superficial form of the space operated on, the 

 arrangement can only be an approximation when con- 

 sidered as a whole. 



Sect. I. — Scientific Treatment of the Arboretum. 



In this section it is proposed to give a sketch of the 

 Natural System of botany as it may be embodied in a 

 living collection of hardy trees and shrubs. This, we 

 are aware, may appear something different from, and dis- 

 cordant with, the other subjects treated in this volume; 

 nevertheless, on mature consideration, we feel constrained 

 either to present it to our readers as absolutely neces- 

 sary to render the remainder of our remarks inteUigible, 

 or to omit the interesting and important subject of the 

 arboretum altogether. We might as well discuss the 

 topography of a country without a map, as describe an 

 arboretum, or give directions for its formation, mthout 



