No. 532] GENETIC AL STUDIES ON (EN OTHER A 221 



{■!) Xo character of either parent was observed to he 

 dominant. (3) It is doubtful whether there would be any 

 material difference between a cross and its reciprocal if 

 each were equally vigorous. (4) Although the extreme 

 types in the culture, approaching somewhat the respec- 

 tive parents, could be readily distinguished, they were 

 connected by transitional forms and a sharp line could 

 not be drawn between two sets of hybrids, such as have 

 been described by De Vries ('07, '08) as " twin hybrids" 

 and reported for crosses between the Oi/a?/r<( group and 

 LdniarcLidiKi. From observations on small cultures dur- 

 ing the season of 1909 (Davis '10, p. 113) the writer was 

 led to believe that "twin hybrids" might be presenl in 

 this cross, but he no longer regards this as probable. 



Hybrids in the F 2 Generation 

 In a recent paper (Davis '10) 1 described two small 

 cultures of hybrids between biennis B and grandiflora D 

 that were grown at the Botanic Garden of Harvard Uni- 

 versity in the season of 1909. Four of the plants of 

 these cultures were of special interest as presenting 

 flowers and inflorescences very similar to Lamarclauna, 

 although differing markedly in foliage. I unfortunately 

 was unable to observe the early development of these 

 plants and for this reason they were not very good forms 

 on which to base studies of their progeny in the F 2 gen- 

 eration. Their seed was, however, sown this season and 

 the cultures, described below, were of interest as indicat- 

 ing the probable behavior of hybrid plants of biennis and 

 firtnidi flora. These four lines will not be cultivated 

 further, since I have in the hybrids 1 <>.:?( > La and 10.30 Lb 



study for the reason that the records of their life hi-tory 

 have been kept in detail. The seeds of these hybrids 

 proved fertile to a very high degree, but it was practicable 

 to grow only a small proportion of the seedlings to 

 maturity. 



