F. Keeble 173 



As indicated in Table II, the giant race has been continued by self- 

 fertilization for four generations, and several hundreds of descendants 

 have been cultivated. All of these have been observed with care, and 

 in the case of 58 plants (Table II) written records of their characters 

 have been kept. All have without exception been true to the giant 

 habit. 



On the other hand all attempts (see Table III) to cross Giant 

 White Queen Star with other varieties have — with one doubtful ex- 

 ception to be mentioned immediately — proved abortive. Whether the 

 giant race be used as the seed parent or as the pollen parent ; whether 

 it be crossed with normal or giant forms, with stellata or sinensis forms, 

 the result is the same. Even when it is crossed with the parental race 

 of White Queen Star, and this cross has been repeated many times, no 

 seed has been obtained except on one occasion, when two fertile seeds 

 were produced (see Table III). The last-named cross has been repeated 

 often and advisedly, because it was recognized that in the success 

 thereof lay by far the best chance of obtaining material suitable in 

 all respects for an experimental study of the genetics of gigantism. 

 Despite the negative results obtained by crossing Giant White Queen 

 Star with other varieties, and inasmuch as it would appear probable, 

 from analoofous cases, that this refractoriness to cross-fertilization will 

 disappear, it seems worth while to record the varieties (see Table III) 

 with which the attempts to cross fertilize Giant White Queen Star 

 have been made. 



The Mendelian phenomena presented by the offspring produced by 

 crossing giant and normal plants are not altogether easy of interpre- 

 tation. This, however, is due rather to the difficulties of experimentation 

 and particularly of observation, than to the complexity of the problem. 

 Since it is evident from the facts recounted already that gigantism is 

 a cell phenomenon, it follows that the genetics of gigantism should be 

 investigated with reference to the cell, and that, if Mendelian results 

 of certain value are to be obtained, the attention of the observer must 

 be directed not only to the dimensions of the individual plants or 

 flowers, but also to those of the cells of the plants with which breeding 

 experiments are made. 



The experiments, the results of which are now to be discussed, 

 were undertaken before this need was realised, and the experiments 

 which were suggested by the advent and cell characteiistics of the 

 mutant Giant White Queen Star have never been made, owing to 

 the obstinate sterility of that form. Hence it must be admitted at 



