8o MUTATIONS, VARIATIONS. AND RELATIONSHIPS OF THE OENOTHERAS. 



varying frequency. In one culture the coefficient of mutability of oblonga 

 was pushed slightly beyond the limit hitherto assigned to it bv De \'ries and 

 it was found to constitute 54 per cent of the atypic derivatives. A survey of 

 all of the results obtained in the New York Botanical Garden since 1902 does 

 not justify the assertion, however, that any change in the frequency of mutation 

 has been induced by cultural conditions, and the only really new feature 

 noticed consisted in the appearance of a new nuitant, which, however, was so 

 unsuited to the climatic conditions that it perished before reaching maturity, 

 an example of the eliminative action of selection in the determination of what 

 mutants shall survive and what shall perish. 



Cultures made from seeds obtained from merchants did not show a fre- 

 quency of the mutants above 1.5 per cent in any instance, which is much less 

 than that observed in the strain growing at Hilversum. The sources from 

 which the seeds were obtained indicate that the species is in a state of muta- 

 bility in various parts of the world, and that it has probably been so for some 

 time. The low frequency of mutation may have been due in part to unsuit- 

 able methods of cultivation, in consequence of which the parental individuals 

 were badly nourished. 



0. hrevistylis was brought to maturity and found to agree in all characters 

 with specimens grown in Amsterdam. This form differs from the parental 

 type chiefly by the retrogressive character of a shortened style, and by gen- 

 eral observation this organ shows a wider range of fluctuation about its average 

 than the same organ in the parent, although no exact examination was made. 

 Despite the fact that this type produces comparatively few seeds it was found 

 by De Vries among the individuals of the parental type in the original locality 

 in which mutation in lamarckiana was observed in 1886, and it has since held 

 its own in competition with the parental type, in a manner demonstrative of 

 the fact that it is possible for a mutant to survive in competition with existing 

 forms. 



O. lata grown from seeds obtained from Professor De Vries and from indi- 

 viduals arising in the pedigreed strains in New York was seen to remain con- 

 stant to its characters. A few tests had been made both in New York and 

 Amsterdam, but no fertilization was secured with its own pollen, although some 

 of it appeared structurally perfect in a microscopic examination. O. lata 

 appearing in a culture from seeds of O. lamarckiana from England, however, 

 included some individuals which likewise produced pollen, and also showed 

 the hitherto unknown capacity of being fertilized by it. The seeds obtained 

 in this way gave rise to a progeny which showed only the constituents usually 

 found in a progeny of this plant when fertilized by lamarckiana. 



O. scintillans grown directly from its own seeds, and also as it appeared as a 

 new mutant in the cultures, was constant in its ever-sporting character. Seeds 

 of this species purely fertilized gave rise, in addition to the type, to a few 



