INTRODUCTION. XXXIX 



a central principle which pervaded and 

 unified his Classes, Orders, Genera, 

 Species; and animated the subordinated 

 whole with a single and almost conscious 

 vitality. 



And now an assured Nomenclature was 

 for the first time possible. An organised 

 System regulated the place of every plant, 

 and the Binomial Nomenclature was de- 

 scriptive of that place. Each plant had 

 two names, a Generic and a Specific. The 

 first was relative to the System, the second 

 determined the Individual. The thirty- 

 one Canons of Linnaeus, by which he 

 guided himself in the construction of this 

 Nomenclature, are famous in the annals of 

 the classificatory Sciences, and a sample 

 of them may be welcome to the reader : 



' i. The names of plants are of two 

 kinds ; those of the class and order which 

 are understood ; and those of the genus 

 and species which are expressed. The 

 name of the class and order never enter 

 into the denomination of a plant. 



2. All plants agreeing in genus are. to 

 have the same generic name. 



