igiS] BARTLETT— MUTATION IN OENOTHERA 85 



It is shown In this paper (i) that the phenomena of mutation 

 are as characteristic and as easily observed in one of the wild 

 small-flowered self-pollinating Onagras as in OenotheraLamarckiana; 

 (2) that the mutations show characters unlike those of any other 

 form with which the parent could have crossed; and (3) that the 

 mutations cannot be ascribed to MendeHan segregation as at 

 present understood. It therefore seems in the highest , degree 

 probable that mutation is a phenomenon which is independent of 

 hybridization, and that the evidence of mutation which De Vries 

 has found in Oenothera Lamarchiana is just as vahd as though 

 that species were known as a wild plant and not suspected of 

 having had a horticultural origin. 



Differential germination 



Several of the most interesting mutations which were observed 

 during the season of 1913 were found quite by chance. One lot 

 of potting soil, in which the seeds of several strains were sown, 

 proved to be a very stiff clay on which a hard crust formed. 

 Germination was so poor that in several cases less than a dozen 

 seedlings resulted from sowing perhaps a thousand or more seeds. 

 It was afterward found that the seeds showed the usual per- 

 centage of germination when sown in good soil. In three different 

 species the small progenies obtained when the seeds were planted 

 under unfavorable conditions disclosed striking mutations, which 

 had survived as a result of differential or selective germination. 

 These mutations might easily have been overlooked in a seed pan 

 containing several hundred seedlings, of which only a few were to 

 be retained and grown to maturity. 



The three mutant species were from widely separated localities. 

 The seeds of one, from Plymouth, Massachusetts, were sent by 

 Professor B. M. Davis; the others were collected by the writer at 

 White Sulphur Springs, W.Va., and Lexington, Ky., respectively. 

 The mutations of the two former species were lost before they 

 matured. It will be useless, therefore, to give an account of their 

 characters or of the cultures in which they appeared until they 

 shall have been found again. In the case of the third species, 



