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E. CARLETON MACDOWELL 



1. DO HIGHER GRADE PARENTS PRODUCE HIGHER GRADE 



CHILDREN ? 



To show what basis there may be for selection to progress, 

 comparisons have been made of children from high and low 

 parents from the same grandparents. All the matings in F, 

 can be used for this purpose, as all the parents were sibs. Curves 

 showing the 35 Fo fraternities were plotted, but they were too 

 numerous for publication. The children from parents of like 

 grades have been grouped together. Table 7 shows the aver- 

 ages of the males and females, the numbers of flies and of families 

 involved in the various types of matings. No increase in the 

 means is found that directly corresponds to the increase in 

 parental values. However, in grouping together children from 

 parents with one or two extra, and comparing them with children 

 from parents with three or four extra, the higher group has, in 

 general, higher means. The low means of the one 4 : 4 mating 

 involves too few individuals to make a serious exception. In 

 the second generation there seems to be a basis for some effective 

 selection. 



Similar comparisons can be made in the later generations. 

 Seven families in F4 came from the same grandparents. Thirteen 

 of the parents were + 5 and one, + 6. Here is a case where 

 the parents are closely alike and one would expect the children 

 in the different families to be closely alike. The curves and the 



TABLE 7 



To shoiv the relationship between the grades of the parents and the means of their 

 children in the second selected generation 



