INTRODUCTION. 
.1 
tor/ of the 'World, Theory of the Earth, or Physical Geography. 
The last of these two objects seemed to me the most important. 
I was passionately devoted to botany and certain parts of zoology, 
and I flattered myself that our investigations might add some new 
species to those already known, both in the animal and vegetable 
kingdoms ; but preferring the connection of facts which have been 
long observed, to the knowledge of insulated facts, although new, 
the discovery of an unknown genus seemed to me far less interest- 
ing than an observation on the geographical relations of the vege- 
table world, on the migrations of the social plants, and the limit 
of the height which their different tribes attain on the flanks of 
the Cordilleras. 
The natural sciences are connected by the same ties which link 
together all the phenomena of nature. The classification of the 
species, which must he considered as the fundamental part of 
botany, and the study of which is rendered attractive and easy 
by the introduction of natural methods, is to the geography 
of plants what descriptive mineralogy is to the indication of the 
rocks constituting the exterior crust of the globe. To compre- 
hend the laws observed in the position of these rocks, to deter- 
mine the age of their successive formations, and their identity 
in the most distant regions, the geologist should he previously 
acquainted with the simple fossils which compose the mass of 
mountains, and of which the names and character are the object 
of oryctognostical knowledge. It is the same with that part of 
the natural history of the globe which treats of the relations 
plants have to each other, to the soil whence they spring, or 
to the air which they inhale and modify. The progress of the 
geography of plants depends in a great measure on that of de- 
scriptive botany ; and it would he injurious to the advancement 
of science, to attempt rising to general ideas, whilst neglecting 
the knowledge of particular facts. 
I have leen guided by these considerations in the course of my 
inquiries ; they were always present to my mind during the period 
of my preparatory studies. When I began to read the numerous 
narratives of travels, which compose so interesting a part of 
modern literature, I regretted that travellers, the most enlight- 
ened in the insulated branches of natural history, were seldom 
possessed of sufficient variety of knowledge to avail themselves 
of every advantage arising from their position. It appeared to 
me, that the importance of the results hitherto obtained did 
not keep pace with the immense progress which, at the end of 
the eighteenth century, had been made in several departments of 
science, particularly geology, the history of the modifications of 
the atmosphere, and the physiology of animals and plants. I 
saw with regret, (and all scientific men have shared this feeling) 
that whilst the number of accurate instruments was daily in- 
