226 DARWIN. 



is it in his system of Evolution as explained above. 

 A very careful reading of this passage shows that 

 in the comparison of methods pursued by man and 

 by Nature, his emphasis is plainly not upon the 

 natural selection but upon the natural succession 

 of types. Man causes types to succeed each other 

 artificially ; Nature also causes types to succeed 

 each other; he does not say that Nature selects 

 the fittest types. A single passage like this is 

 often very misleading ; we must always study the 

 author's w^hole context. A century earlier Buffon 

 had much more clearly expressed the idea of the 

 survival of the fittest species of plants. 



In 1855 appeared an article' by Alfred Russel 

 Wallace, " On the Law which has regulated the 

 Introduction of New Species." This contains a 

 very strong argument for the theory of descent, 

 as explaining the facts of classification, of distribu- 

 tion, and of succession of species in geological time 

 during the great changes upon the earth. Wallace 

 at this time showed himself a strong and fearless 

 evolutionist, although he had not apparently arrived 

 at his subsequent theory of the causes of change. 



State of Opinion in the Mid-Century. 



In all that has passed in these lectures the anti- 

 evolutionists have been kept in the background. Yet 



1 Annals and Magazine of Natural History, September, 1855. Repub- 

 lished in 1870 in Contributions to the Theory of Natural Selection. .4 Series 

 of Essays. Macmillan & Co., London. 



