548 



THE AMEBIC AX NATURALIST 



[Vol. XLVII 



two classes of gametes with and without the factor re- 

 sponsible for this character. 



Although it is true that the form biennis D in later 

 generations has been uniform as to the stem coloration 

 described above it by no means follows that the original 

 plant of 1910, which furnished the gametes of the cross, 

 was homozygous for this character. I have already noted 

 the fact (Davis, '12a, p. 386) that types occur wild similar 

 to biennis D except for their clear green stems. Con- 

 sequently the original plant may have been heterozygous 

 with respect to factors for red papilla? and in my later 

 generations I may have isolated a homozygous line. 



Last summer I grew the reciprocal of the cross de- 

 scribed above, i. e., a cross biennis D X grandiflora B 

 which involved the same parent plants as in the first. 

 The F x generation of 103 plants, culture 12.11, was 

 brought to maturity and consisted of the same two clearly 

 defined classes. Class [, consisting of 87 plants, presented 

 the stem coloration of the biennis parent (red papillae on 

 green portions of the stem). Class II, consisting of 16 

 plants, presented the stem coloration of the grandiflora 

 parent (stem above clear green). There was a dispro- 

 portion of the numbers as in the previous case, but in the 

 reciprocal cross the plants with red papillae were in a 

 large majority, 87:16, instead of being in a small mi- 

 nority, 12 :168, present in the first cross. Other peculiari- 

 ties of these classes were the same as in the first cross. 

 Again the mixed conditions in the Fj reciprocal cross sug- 

 gested the probability that the biennis parent, in this case 

 female, was heterozygous with respect to the red colora- 

 tion of the papillate glands and that it also formed two 

 classes of gametes with and without the factor respon- 

 sible for this character. 



The two classes of hybrids in the F, generation de- 

 scribed above appear to present a phenomenon similar to 



'07) which result when 

 mated by Lamarckiana 



