8 A JOURNEY IN BRAZIL. 



in our mode of work, as compared with that of former 

 investigators. When less was known of animals and plants 

 the discovery of new species was the great object. This 

 has been carried too far, and is now almost the lowest kind 

 of scientific work. The discovery of a new species as such 

 does not change a feature in the science of natural history, 

 any more than the discovery of a new asteroid changes 

 the character of the problems to be investigated by astrono- 

 mers. It is merely adding to the enumeration of objects. 

 We should look rather for the fundamental relations among 

 animals ; the number of species we may find is of impor- 

 tance only so far as they explain the distribution and lim- 

 itation of different genera and families, their relations to 

 each other and to the physical conditions under which they 

 live. Out of such investigations there looms up a deeper 

 question for scientific men, the solution of which is to be 

 the most important result of their work in coming genera- 

 tions. The origin of life is the great question of the day. 

 How did the organic world come to be as it is ? It must 

 be our aim to throw some light on this subject by our pres- 

 ent journey. How did Brazil come to be inhabited by the 

 animals and plants now living there ? Who were its inhab- 

 itants in past times ? What reason is there to believe that 

 the present condition of things in this country is in any 

 sense derived from the past ? The first step in this investi- 

 gation must be to ascertain the geographical distribution 

 of the present animals and plants. Suppose we first ex- 

 amine the Rio San Francisco. The basin of this river is 

 entirely isolated. Are its inhabitants, like its waters, com- 

 pletely distinct from those of other basins ? Are its species 

 peculiar to itself, and not repeated in any other river of 

 the continent? Extraordinary as this result would seem, 



