136 PIONEERS OF EVOLUTION. 



But, of still greater moment, is a letter in which 

 Wallace tells Bates that he begins " to feel dissatis- 

 fied with a mere local collection. I should like to 

 take some one family to study thoroughly, princi- 

 pally with a view to the theory of the origin of 

 species." The two friends had often discussed 

 schemes for going abroad to explore some virgin 

 region, nor could their scanty means prevent the 

 fulfilment of a scheme which has enriched both sci- 

 ence and the literature of travel. The choice of 

 country to explore was settled by Wallace's perusal 

 of a little book entitled A Voyage up the River 

 Amazons, including a Residence in Para, by W. H. 

 Edwards, an American tourist, published in Murray's 

 Family Library, in 1847. I" the autumn of that 

 year Wallace proposed a joint expedition to the 

 river Amazons for the purpose of exploring the , 

 Natural History of its banks; the plan being to 

 make a collection of objects, dispose of the dupli- 

 cates in London to pay expenses, and gather facts, 

 as Mr. Wallace expressed it in one of his letters, 

 " towards - solving the problem of the origin of 

 species." 



The choice was a happy one, for, except by the 

 German zoologist Von Spix, and the botanist Von 

 Martins in 1817-20, and subsequently by Count de 

 Castelnau, no exploration of a region so rich and 

 interesting to the biologist had been attempted. 

 Early in 1848 Bates and Wallace met in London 

 to study South American animals and plants in the 



