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THE AMERICAN NATURALIST [Vol. XLVI 



pronounced form in the F 1 hybrids rendering them less 

 favorable for my studies than the crosses with the strains 

 grandiflora B or D. The culture was interesting since 

 it presented two classes of F 1 hybrids as in cultures 11.35 

 and 11.32, separated by identical groups of characters. 

 Out of 144 plants brought to maturity 4 plants were of 

 Class I and 140 plants were of Class II. 



A culture of the reciprocal cross of these types, biennis 

 D X grandiflora I (11.39), was started late in the season 

 after the appearance of the paper of De Vries ( '11) on 

 double reciprocal crosses, but the culture was unable to 

 reach maturity. By September 15, out of a total of 171 

 rosettes, 31 had sent up side shoots of sufficient length 

 (2-4 dm.) to determine the coloration of the papillate 

 glands; 21 of these plants had red glands on a green 

 stem, and in 10 plants the glands were uncolored. 



4. grandiflora DxTracyi (11.33).— The F x hybrids 

 of this cross were remarkable plants 2.5-3 m. high, 

 developing from transitory rosettes and with a luxuriant 

 foliage of narrow leaves. As noted before, the plants 

 were very far from Lamarckiana. It is a cross that is 

 likely to occur in nature where the two species grow 

 together as at Dixie Landing, Alabama, and this possi- 

 bility must be reckoned with in analyses of the two 

 species. (Enothera Tracyi has the red coloration of 

 the papillate glands characteristic of biennis B. The 

 40 plants of the culture fell sharply into two classes dis- 

 tinguished by characters similar to those of the crosses 

 between biennis D and grandiflora. There were 3 plants 

 of Class I, with red glands, etc., and 37 of Class II. 



The cultures of the F x hybrids as recorded above have 

 given data that can not be satisfactorily discussed until 

 similar crosses have been made with parents that are 

 beyond question homozygous. My strains grandiflora B 

 and D have now been carried in pure line for three gen- 

 erations and have proved uniform, but the parent plants 

 biennis D and Tracyi were from wild seed. It does not 

 seem probable that the latter types are heterozygous, for 



