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 Jardin 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 bcennis, 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 Linnzan 
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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