58 



THE AMEBIC AX NATURALIST [Vol. LII 



necessitate a separate summary for the crossover and non-cross- 

 over classes of the coupling and repulsion families. The devi- 

 ations from the average are more than twice the probable error 

 in ears 1, 3, 4, and 9, between one and two times in ears 5 and 7, 

 and less than the probable error in ears 2, 6, and 8. 



: Colored X Waxy 



4 — mm 



101(9) X 100(9) 102 60 

 100(5) X 101(4) 170 49 

 101 (3) X 100(8) 124 53 



2.3 1.51 

 2.3 2.57 

 1.8 1.55 



69 220 195 60 

 18 114 128 1 



Owing, perhaps, to the difficulty in separating waxy from 

 corneous grains the percentage of waxy grains for the total of 

 the 9 ears is only 47.7 ± .6. The deviation from the expected 50 

 per cent, is nearly four times the probable error, indicating a 

 poor fit. The percentage of colorless grains is 48.4 and the de- 

 viation is two and two thirds times the probable error. Here the 

 separation is accomplished with a somewhat greater degree of 

 accuracy. On the whole, the data seem to show conclusively 

 that we are dealing with a linkage between waxy endosperm 

 and one of the aleurone factors. 



Ear No. 10, which is derived from a non-linkage family and 

 included in the table for comparison with the first nine ears, is 

 also the result of a back cross. The per cent, of crossing over is 

 49.3, which is practically equivalent to independent inheritance. 

 The deviation from 26.7 per cent, of crossing over is 16.74 times 

 the probable error and the odds against this being due to ran- 

 dom sampling are enormous. 



Evidence that the C Factor for Aleurone Color is 



Although the linkage data are interesting and valuable, it is 

 perhaps of greater interest and value in the study of maize in- 



