MODES OF INHERITANCE IN HYBRIDS 481 



Pigment characters of hybrids between F. heteroclitus and F. majalis 



It should not be necessary to repeat the facts concerning these 

 crosses since they form the subject-matter of Bancroft's paper. 

 An examination of his table 1 will reveal the facts as they ap- 

 peared to him. A reexamination of the same data, however, has 

 convinced me that there is much more blending or intermediate 

 inheritance and less pure dominance than Bancroft leads us to 

 expect. He lists the following characters which he believes to 

 be dominant: 



1 . " The character — presence of many large red yolk chromato- 

 phores (F. heteroclitus condition) is dominant over the character — - 

 presence of few small yolk chromatophores (F. majalis charac- 

 ter)." Yet in the table and elsewhere he states that in the 

 hybrids these elements are fewer, smaller and less branched than 

 in the dominant parent. 



2. "The size and shape of the black yolk chromatophores of 

 F. heteroclitus is dominant over the size and shape of these same 

 cells in F. majalis." Yet in his table we learn that these cells 

 are smaller and have many minute processes, showing that the 

 F. majalis influence is evident in the matter of size and shape. 



3. "The presence of a first crop of head chromatophores ap- 

 pearing before the majority of the head chromatophores (F. heter- 

 oclitus condition) is dominant over absence of this crop of head 

 chromatophores (F. majalis condition)." I have been unable to 

 convince myself of the validity of this character since in many 

 cases I have observed that the first crop consists of one chroma- 

 tophore, that two or more followed after a considerable interval, 

 and that the others came on gradually so that I have been 

 unable to decide what constituted the first crop. All that I have 

 been able to say for certain is that the first few chromatophores 

 seem to be somewhat larger and to take longer to develop than 

 the subsequent ones. A similar situation exists in F. diaphanus 

 and here there is no distinction between the earlier and later 

 chromatophores. I still believe that the time of appearance of 

 the first chromatophores in the hybrids is strictly an intermediate 

 character, and as such not an example of dominance. 



