IV 



to those which have been already describe 

 ed ; but preferring the connection of facts* 

 which have been long observed* to the 

 knowledge of insulated facts, although 

 they were new, the discovery of an un- 

 known genus seemed to me far less inter- 

 esting than an observation on the geogra- 

 phical relations of the vegetable world, 

 on the migration of the social plants, and 

 the limit of the height which their differ- 

 ent tribes attain on the flanks of the Cor- 

 dilleras. 



The natural sciences are connected by 

 the same ties that link all the phenomena 

 of nature. The classification of the species 

 which we ought to consider as the funda- 

 mental part of botany , and the study of which 

 is become more attractive and more easy by 

 the introduction of natural methods, is to 

 the geography of plants, what descriptive 

 mineralogy is to the indication of the rocks 

 which constitute the exterior crust of the 

 globe. To comprehend the laws which are 

 observed in the position of these rocks, and 

 determine the age of their successive for- 

 mations, and their identity in the most 

 distant regions, the geologist ought to be 



