SHORTER ARTICLES AND DISCUSSION 



ADDITIONAL EVIDENCE OF MUTATION IN OENOTHERA 



In a group of recent papers Bartlett reports on the remarkable 

 behavior of certain wild species of (Enothera grown in large cul- 

 tures, which behavior he regards as strong evidence for the muta- 

 tion theory of De Vries. The facts are presented very clearly, 

 but there is, however, a point of view which has not been consid- 

 ered in the interpretation of the conditions in his material, certain 

 possibilities that must be reckoned with in the critical examina- 

 tion of such evidence. The suggestions that I shall offer will 

 concern chiefly the genetic purity of the forms studied, a condi- 

 tion which is of course basic to studies on mutation as well as to 

 Mendelian experimentation. 



(Enothera pratincola Bartlett 1 is a small-flowered, close-polli- 

 nated species apparently common in the North Central States. 

 Seven strains derived from wild mother plants at Lexington, 

 Kentucky, gave rise to a variant, nummularia, which differs from 

 the parent type in the form of the seedling leaves, foliage, pubes- 

 cence of the ovary and calyx, and in the manner in which the 

 calyx is ruptured in the opening of the flower. Nummularia 

 appeared with a frequency of about 1 plant to every 400 seeds 

 sown and 1 plant to every 250 seedlings since the germination of 

 the seeds in the earth was 66 per cent. Two of the strains pro- 

 duced nummularia in both the F 1 and F 2 generations. Further 

 studies will be undertaken to determine whether pratincola will 

 continue to give nummularia or whether it may perhaps in later 

 generations produce stable individuals. Nummularia develops a 

 low percentage of good pollen (less than 50 per cent.) while 

 pratincola has a high proportion (90 per cent.) ; nummularia also 

 forms very few good seeds to a capsule, and of these only 34 per 

 cent, are viable. Small cultures grown from nummularia seeds 

 gave no plants of pratincola, but certain new forms appeared. 

 The high degree of sterility both gametic and zygotic shown by 

 nummularia is striking and demands study, for it will make a 

 difference in the interpretation of the behavior of this plant 

 whether the sterility is physiological or genetic in character. 



i Bartlett, H. H., "Additional Evidence of Mutation in (Enothera," 

 Bot. Gas., Vol. LIX, p. 81, 1915. 



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