216 THE EVOLUTION OF CONTINUITY 



would be necessary for the production of acquired varia- 

 tion ; but natural selection would not at all be necessary 

 for the preservation of the acquired variation. By its 

 action in insuring the fullest percentage of true-breds it 

 could, however, on occasion, help to preserve a new species 

 in certain conditions of the struggle for existence. 



In the Mutation Theory, to which reference has been 

 made, De Vries holds that new species originate through 

 sudden change and not by gradual transformation. The 

 sudden changes he calls " mutations," and his belief is that 

 all simple characters have originated in them. The commonly 

 termed " sport " is an example of an organism exhibiting 

 mutations. 



In our opinion the mutation can only be acquired 

 variation, and if this be accepted, then our theory is in 

 fundamental agreement with that of De Vries. For our 

 view is that all simple characters of plants and animals 

 have originated as acquired variations. 



Clearly, the natural variation, or " fluctuation," exhibited 

 in the transmission of fixed hereditary characters is quite 

 distinct from acquired variation, and being in no sense a 

 matter of modification, cannot be held to have any influence 

 in the origination of new species. 



