SELECTIVE FERTILIZATION IN POLLEN MIXTURES. 265 



The pollen mixtures I, 19 and 20 were also applied to a third 

 strain distinct from either of the two used in supplying the 

 pollen. The resulting two lots of seed in each case were both 

 cross-fertilized and probably showed hybrid vigor in the seed in 

 about equal amount. Heterosis is clearly apparent in the plants 

 of similar crosses involving the same or closely related material 

 and is approximately equal. 



The data from each pollen mixture are presented in the form 

 of an appendix. Since the arrangement is the same in all the 

 tables these are given in the simplest form possible and a descrip- 

 tion of one applies to all. In the tables the headings for the 

 four different classes of seed are A X A, A X B, B X A, B X B 

 and in the three mixtures I, 19 and 20 there are in addition the 

 out-crossed seeds C X A, and C X B. In every case the pistil- 

 late parent is given first. These headings when expanded in 

 detail are as follows : 



A X A = Self-fertilized seeds from color-carrying pollen. 



A X B == Cross " non-color " 



B X A == Cross " color 



B X B = Self " non-color " 



C X A == Out-crossed " color 



C X A == Out " non-color" 



On every plant there are two kinds of seeds indicating the 

 relative fertilizing efficiency of the two kinds of pollen in the 

 mixture used. The number of seeds from individual plants are 

 given in the tables under their respective headings, A X A and 

 A X B seed from the same inflorescence and B X A and B X B 

 seeds from another and C X A and C X B from a third. The 

 total number of seeds is summed up below the line. Next to that 

 is given the per cent, of error found upon testing the accuracy of 

 the classification. This figure is used to calculate the amount of 

 error based upon all the seeds obtained. Not more than about 

 125 seeds were grown in each lot except in two cases as shown in 

 Table III. The calculated amount of wrongly classified seeds is 

 given on the line below the per cent, of error, then follows the 

 corrected numbers after the proper additions and subtractions 

 have been made. After that is placed the observed proportion 



