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CHAPTER XII. 



THE GROWTH OF WALLACE'S CONVICTIONS ON EVOLU- 

 TION AND DISCOVERY OF NATURAL SELECTION — 

 BORNEO 1855 — TERNATE 1858. 



We have already seen in the earlier part of this 

 volume, the gradual development of the theory of 

 N"atural Selection in the mind of Darwin, and the long 

 succession of experiments and observations which he 

 undertook before he could bring himself to publish any- 

 thing upon the subject, as well as the conditions which 

 forced him to a hurried publication in the end. It 

 is of the deepest interest to compare with this the 

 account which Wallace has given us of the mental 

 process by which he arrived at the same conclusions. 



This deeply interesting personal history has only 

 been known during the last few years ; in 1891 Wallace 

 republished his "Essays on Natural Selection" in 

 one volume, combined with "Tropical Nature," and 

 he has added (on pp. 20, 21) the following introductory 

 note to Chapter II., viz. the reprint of his Linnean 

 Society Memoir " On the Tendencies of Varieties to 

 depart indefinitely from the Original Type." The 

 note is here reprinted in full : — 



" As this chapter sets forth the main features of a theory 

 identical with that discovered by Mr. Darwin many years 



