10 EVOLUTION OF TO-DAY. 



is more than this ; it is at the same time an attempt 

 at an explanation of the causes of evolution. It 

 not only claims that species have been slowly 

 evolved from each other, but it also gives an ac- 

 count of the manner in which they have arisen, and 

 the laws which govern their gradual modification. 

 It is, therefore, possible to accept evolution and to 

 reject Darwinism completely ; to believe that species 

 have been evolved from each other, but to deny that 

 Darwin has discovered the causes of this evolution. 

 And so with various other theories of evolution, 

 of which science has proposed several. All agree 

 as to the evolution of species from each other, but 

 no two explain the fact in the same manner. For 

 we must recognize two quite different questions in 

 considering the subject. The first is as to the fact 

 of evolution. We must discover, if possible what 

 has been the history of organisms ; whether each 

 species is to be considered as an abrupt innovation, 

 utterly independent of all others i. t., a special 

 creation, or whether species have been derived from 

 each other by the ordinary methods of reproduction 

 aud slow change. If it is discovered that the evi- 

 dence is sufficient to prove evolution to be a fact, 

 or to render it probable, a second and more difficult 

 question remains. We must discover what are the 

 laws which regulate this evolution, and must deter- 

 mine how species have been derived from each other, 

 whether slowly or abruptly, whether by internal or 

 external forces, and other problems of like nature. 

 In reality these two questions have been considered 

 simultaneously, all theories of evolution attempting 



