The Making of Species 



which it has been built up. Boulenger and 

 Bailey have both studied this plant, and they 

 have not been able to witness all the mutations 

 of which De Vries speaks, so that the former 

 says, " The fact that Oenothera lamarckiana was 

 originally described from a garden flower, grown 

 in the Paris Jar din des Plantes, and that, in spite 

 of diligent search, it has not been discovered 

 wild anywhere in America, favours the prob- 

 ability that it was produced by crossing various 

 forms of the polymorphic Oenothera biennis, which 

 had been previously introduced in Europe." 



It has further been objected that, even if 

 these various forms which Lamarck's evening 

 primrose throws off are true mutations, they 

 ought not to be called new species, for they do 

 not differ sufficiently from the parent species 

 to deserve the name of new species. The reply 

 to this criticism is that De Vries asserts that 

 mutations produce new elementary species, which 

 are not the same things as new species in the 

 ordinary sense of the term. Most Linnaean 

 species differ from one another to a far greater 

 extent than do elementary species. It seems 

 to us quite plain that new species arise, not by 

 a single mutation, but by two or three successive 

 mutations which occur in various parts of an 

 organism. 



First arises a well-marked variety, by a single 

 mutation. Subsequent mutations follow, so that 



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