No. 547] GENETIC Ah STUDIES 



the reason that both have the habit of dose pollination, 

 but, nevertheless, the forms are not above suspicion. As 

 the data stand the most interesting features shown by 

 the F x hybrids are: (1) The absence of dominance oil 

 the part of any character of the parents, including the 

 coloration of the papillate glands, (2) the sharp differ- 

 entiation of two classes of hybrids (twin hybrids?) 

 clearly distinguished by groups of characters, and (3) 

 the absence of marked patroclinous or matroclinous con- 

 ditions in either of these two classes. The differentia 

 tion of two classes of hybrids has been a new phenomenon 

 in my experience with F x hybrids of (Enothera which 

 have previously proved remarkably uniform except for 

 the extremes represented by a few plants somewhat ap- 

 proaching the respective parents. 



6. Hybrids in the F 2 Generation from the F t Hybrid 

 Plants 10.30La and 10.30L&. 

 In my paper of a year ago (Davis, '11, pp. 211-217) 

 two plants were described and figured which among the 

 hybrids up to that time most closely resembled (Enothera 

 Lamarckiana. They were the F, hybrid plants designated 

 10.30La and 10.30L6, the result of the cross grandiflora 

 B X biennis A. Cultures from self-pollinated seed of 

 these two plants were grown in the season of 1911, giving 

 considerable data on the behavior of such a cross in the 



These Fo hybrids were not grown with the expectation 

 that any of the plants would be taxonomically the same 

 as Lamarckiana, since it had been apparent for some 

 months that the strain biennis A is not so favorable a 

 biotype as manv others to cross with grandiflora in the 

 hope of obtaining Lamarckiana-hke hybrids. The 

 hybrids were grown to satisfy my keen desire to observe 

 the behavior of such a cross and in the hope that its study 

 would prove helpful in the planning of future work. 



The mass of the F, hybrids held in their characters 



