物种起源的基础

We know from the contents of Charles Darwin's Note Book of 1837 that he was at that time a convinced Evolutionist{1}. Nor can there be any doubt that, when he started on board the _Beagle_, such opinions as he had were on the side of immutability. When therefore did the current of his thoughts begin to set in the direction of Evolution? {1} See the extracts in _Life and Letters of Charles Darwin_, ii. p. 5. We have first to consider the factors that made for such a change. On his departure in 1831, Henslow gave him vol. I. of Lyell's _Principles_, then just published, with the warning that he was not to believe what he read{2}. But believe he did, and it is certain (as Huxley has forcibly pointed out{3}) that the doctrine of uniformitarianism when applied to Biology leads of necessity to Evolution. If the extermination of a species is no more catastrophic than the natural death of an individual, why should the birth of a species be any more miraculous than the birth of an individual? It is quite clear that this thought was vividly present to Darwin when he was writing out his early thoughts in the 1837 Note Book{4}:--"Propagation explains why modern animals same type as extinct, which is law almost proved. They die, without they change, like golden pippins; it is a _generation of species_ like generation _of individuals_." "If _species_ generate other _species_ their race is not utterly cut off." {2} The second volume,--especially important in regard to Evolution,--reached him in the autumn of 1832, as Prof. Judd has pointed out in his most interesting paper in _Darwin and Modern Science_. Cambridge, 1909. {3} Obituary Notice of C. Darwin, _Proc. R. Soc._ vol. 44. Reprinted in Huxley's _Collected Essays_. See also _Life and Letters of C. Darwin_, ii. p. 179. {4} See the extracts in the _Life and Letters_, ii. p. 5.…