32 Darwinism and Other Essays. 



plies all that was required to complete the proof 

 of the Darwinian theory. The theory not only 

 alleges a vera causa^ and is not only confirmed by 

 the unanimous import of the facts of classification, 

 embryology, morphology, distribution, and succes- 

 sion ; but it has further succeeded in tracing the 

 actual origination of one generic type from an- 

 other, through gradual " descent with modifica- 

 tions." And thus, within a score of years from 

 its first announcement, the daring hypothesis of 

 Mr. Darwin may fairly claim to be regarded as 

 one of the established truths of science. 



December, 1876. 



