The Discovery of Natural Selection 



adaptation of the species to the changing conditions would 

 be brought about ; and as great changes in the environment 

 are always slow, there would be ample time for the change 

 to" be effected by the survival of the best fitted in every 

 generation. In this way every part of an animaPs organ- 

 ism could be modified as required, and in the very process 

 of this modification the unmodified would die out, and 

 thus the definite characters and the clear isolation of each 

 new species would be explained. The more I thought over 

 it the more I became convinced that I had at length found 

 the long-sought-for law of nature that solved the problem 

 of the origin of species. For the next hour I thought 

 over the deficiencies in the theories of Lamarck and of the 

 author of the ' Vestiges,' and I saw that my new theory 

 supplemented these views and obviated every important 

 difficulty. I waited anxiously for the termination of my 

 fit (of fever) so that I might at once make notes for a 

 paper on the subject. The same evening I did this pretty 

 fully, and on the two succeeding evenings wrote it out 

 carefully in order to send it to Darwin by the next post, 

 which would leave in a day or two.''^ 



The story of the arrival of this letter at Down, and of 

 the swift passage of events between the date on which Dar- 

 win received it and the reading of the *^ joint communica- 

 tions '' before the Linnean Society, has been often told. 

 But few, perhaps, have enjoyed the privilege of reading 

 the account of this memorable proceeding as related by 

 Sir Joseph Hooker at the celebration of the event held by 

 the Linnean Society in 1908. 



As, therefore, the correspondence (pp. 127-320) between 

 Wallace and Darwin during a long series of years conveys 

 many expressions of their mutual appreciation of each 

 other's work in connection with the origin of species, it 



^ " My Life," 1. 361-3. 

 109 



