Theories of Evolution 9 



row limits as far as the present methods of 

 selection go. But the question remains to be 

 solved, whether our methods are truly the right 

 ones, and whether by the use of new princi- 

 ples, new results might cause the balance of 

 opinion to favor the opposite side. 



Of late, a thorough and detailed discussion of 

 the opposing views has been given by Morgan, 

 in his valuable book on Evolution and Adapta- 

 tion. He has subjected all the proposed theo- 

 ries to a severe criticism, both on the ground of 

 facts, and on that of their innate possibility and 

 logical value. He decides in favor of the mu- 

 tation-theory. His arguments are incisive and 

 complete, and wholly adapted to the compre- 

 hension of all intelligent readers, so that his 

 book relieves me entirely of the necessity of 

 discussing these general questions, as it could 

 not be done in a better or in a clearer way. 



I intend to give a review of the facts obtained 

 from plants which go to prove the assertion, 

 that species and varieties have originated by 

 mutation, and are, at present, not known to orig- 

 inate in any other way. This review consists 

 of two parts. One is a critical survey of the 

 facts of agricultural and horticultural breed- 

 ing, as they have accumulated since the time of 

 Darwin. This body of evidence is to be com- 

 bined with some corresponding experiments 



