78 LIFE OF DARWIN. 



leading results of his labours, as well as those of his able 

 correspondent, should together be laid before the public." 



In these papers, read on July i, 1858, Darwin's 

 share amounts to little more than six pages, yet within 

 this space he describes the geometrical rate of increase of 

 animals, the checks that occur, the effects of changed con- 

 ditions, the natural selection of the better equipped forms 

 resulting from the struggle for existence, and the influence 

 of sexual selection. Wallace insists on essentially the same 

 view, which he calls that of progression and continued 

 divergence. " This progression, by minute steps, in 

 various directions, but always checked and balanced by 

 the necessary conditions, subject to which alone existence 

 can be preserved, may, it is believed, be followed out so 

 as to agree with all the phenomena presented by organ- 

 ised beings, their extinction and succession in past ageSj 

 and all the extraordinary modifications of form, instinct, 

 and habits which they exhibit." Those who read 

 Wallace's original essay can best appreciate the extra- 

 ordinary simplicity and nobility of character which 

 inclined the elder naturalist, who had so long held the 

 same views, to step aside in favour of the younger man, 

 who from different researches was led to such similar 

 conclusions. It may here be added that Hooker, in the 

 Introductory Essay to the " Flora Tasmania?," dated 

 November 4, 1859, before the publication of the "Origin 

 of Species," but after seeing much of it in manuscript, 

 accepted and advocated the view that species are 

 derivative and mutable, and developed it as regards the 

 geographical distribution of plants. 



