THE 'NATURALIST'S VOYAGE.' 3 



parison of the fauna of South Africa and South America, and 

 the vegetation of the two continents. The interest of the 

 discussion is that it shows clearly our a priori ignorance of 

 the conditions of life suitable to any organism. 



There is a passage which has been more than once quoted 

 as bearing on the origin of his views. It is where he dis- 

 cusses the striking difference between the species of mice on 

 the east and west of the Andes (ist edit. p. 399) : " Unless we 

 suppose the same species to have been created in two 

 different countries, we ought not to expect any closer simi- 

 larity between the organic beings on the opposite sides of 

 the Andes than on shores separated by a broad strait of the 

 sea." In the 2nd edit. p. 327, the passage is almost verbally 

 identical, and is practically the same. 



There are other passages again which are more strongly 

 evolutionary in the 2nd edit., but otherwise are similar to the 

 corresponding passages in the ist edition. Thus, in describing 

 the blind Tuco-tuco (ist edit. p. 60 ; 2nd edit. p. 52), in the 

 first edition he makes no allusion to what Lamarck might 

 have thought, nor is the instance used as an example of 

 modification, as in the edition of 1845. 



A striking passage occurs in the 2nd edit. (p. 173) on the 

 relationship between the " extinct edentata and the living 

 sloths, ant-eaters, and armadillos." 



" This wonderful relationship in the same continent between 

 the dead and the living, will, I do not doubt, hereafter throw 

 more light on the appearance of organic beings on our earth, 

 and their disappearance from it, than any other class of facts." 



This sentence does not occur in the 1st edit, but he was 

 evidently profoundly struck by the disappearance of the 

 gigantic forerunners of the present animals. The difference 

 between the discussions in the two editions is most instructive. 

 In both, our ignorance of the conditions of life is insisted on, 

 but in the second edition, the discussion is made to lead up to 

 a strong statement of the intensity of the struggle for life. 



B 2 



