136 STUDIES IN INDUN COTTONS 



characters are merely two outward expressions of the same struc- 

 tural peculiarity of which the vegetative period, being most readily 

 determinable, has been adopted in the present work. 



Balls (2) has adopted the same method of record. He further 

 has traced out a certain periodicity in the appearance of the subse- 

 quent flowers— a periodicity which has not been investigated by us. 



When a cross is effected between two plants, one of which 

 belongs to a sympodial, and the other to a monopodial type, the 

 plants of the Fi generation possess a vegetative period which is 

 intei'mediate between those of the two parental types. This inter- 

 mediate position, however, does not correspond to the mean of the 

 two parental values, but invariably approximates in a greater or 

 less degree to that of the sympodial parent. 



In the Fo generation the plants form a continuous series in 

 which every degree of length of vegetative period is obtained. It 

 is noticeable, however, that while those individuals of the F,, series 

 which have the shortest vegetative period are in flower as soon as, 

 or even before, the plants of the parental type, in no case does the 

 vegetative period equal in length that of the monopodial parental 

 type. In other words, while the full sympodial type appears com- 

 paratively frequently the full monopodial type only rarely or never 

 does so. The divergence from the mean length of the parental 

 vegetative periods noticed in the Fj generation is here even more 

 marked. 



Table XIX illustrates the point for o separate crosses in 

 which Type 3 is taken as the monopodial parent with a prolonged 

 vegetative period. Owing to the seasonal variation which has been 

 referred to above, it is not possil^lc to Jiiakc a direct comparison 

 between the successive generations of such crosses. I^'or tliis icason 

 the comparison nuist be effected indirectly by reference to the figures 

 obtained in successive years foi- the parent types. In the present 

 case we appear to possess an example of partial dominance com- 

 bined with incomplete resolution of the component factors in subse- 

 quent generatioiLs, though it may l)c (juestioned whethci- such in- 

 complete resohjtion is ;i rcahty. A\'c ai-e dealing here with a case 

 in which the experimental error of the method of record is inde- 



