HEREDITY, AND THE ORIGIN OF SPECIES. 15 
Others were perfect and vigorous both vegetatively and 
reproductively, and have been found capable of sustaining 
competition with the parental type. Of these rubrinervis 
grows more rapidly, germinates its seeds more quickly, 
and makes more numerous branches, and bids fair to be 
able to win out in a struggle with the parent in all of the 
phases of the struggle. Gigas is a more vigorous form 
than the parent, and both it and rubrinervis show a ten- 
dency to predominate when crossed with the parent. Bre- 
vistylis was found in the original location from which the 
mutating strain was taken, and as it has not appeared in 
any of the pedigreed cultures of the parent type in twenty 
years and still maintains itself in the original locality, it 
may be designated as a mutant which not only has arrived, 
but has survived under perfectly natural conditions. Re- 
cent cultures in the New York Botanical Garden from 
seeds of Lamarck’s evening-primrose, sent from various 
parts of the world where the species is under cultivation, 
demonstrate that it is not alone the plants observed by 
De Vries at Hilversum are mutating, but the same deriva- 
tives are being given off in widely separated localities. 
Purely-pedigreed strains of other species of evening- 
primroses have also been tested with the result that I am 
able to announce that three species are mutating, in lines 
of descent which came from wild plants one and two years 
ago. The common evening-primrose, Oenothera biennis, 
gives rise to one atypical individual in every two hundred 
seedlings, which during its entire development is contin- 
uously different from the parent in many features. It re- 
produces itself, after the manner of scintillans, appearing 
to be eversporting and giving many of the parental indi- 
viduals in the purely fertilized seeds. Within the last two 
months a single rosette representing a new and unknown 
type has appeared in the seed-pans appearing to be a mu- 
tant which is found not more than once in twelve or fifteen 
