EARLY TESTING AND RECURRENT SELECTION 413 



represent the oil percentages of the original selfed ears. Two lines were lost 

 during the course of inbreeding because of failure to produce any pheno- 

 typically desirable plants. The eight lines remaining however represent eight 

 of the ten lines comprising the recurrent selection series. The values pre- 

 sented for the So generation represent the mean of all ears of a particular 

 family which were analyzed. In S3 to S5 the value plotted represents the 



60 



30 



60 







> 30 



O 

 6 



60 



30 



/«'• Cyc/e 



^'^ Cycle 



j.o 40 SO ttO 70 eo 9.0 zoo no 

 Oil Parcznfogc In Groin 



12 O 13.0 



Fig. 26.3 — .\ comparison of the frequency distributions of oil percentage in the corn kernel, 

 in the original population, Illinois High Oil X wxOs420, and after one and two cycles of 



recurrent selection. 



mean for the sibling population in the direct line of descent. If the highest 

 values in each generation had been plotted instead of the means, the picture 

 would have been essentially the same except that the fluctuation from gen- 

 eration to generation would have been increased. The eight lines exhibited 

 somewhat different patterns during the course of inbreeding. Si.x of the eight 

 lines exhibited an increase, and two a decrease in oil j)ercentage. There does 

 not appear to be any consistent trend within the families from generation to 

 generation. It would appear that chance has played a very important role in 

 spite of the intensive selection practiced . 



