138 



EDWIN CARLETON MACDOWELL 



STANDARD DEVIATIONS 



EXTRA BRISTLES 



4 6 8 10 12 14 16 18 20 22 24 26 28 30 



STANDARD DEVIATIONS 



FEMALES 



EXTRA BRISTLES 



!0 12 14 16 18 20 22 24 26 28 30 



B 



Fig. 10 Standard deviations of tlie extracted race compared with the stand- 

 ard deviations of the high race. 'A' based on sons, 'B,' on daughters. As the 

 similarity of the standard deviations of the return and high races indicates sim- 

 ilarity of the races, so the differences in the variability of the extracted and the 

 high races indicate dissimilarity in these two races. 



duced lower children. But after this, the means of the off- 

 spring were completely independent of the means of their parents. 

 Although this extracted race responded to the same environment 

 in the same general way as the high race, there was some sort 

 of a restriction that inhibited the production of the higher 

 bristle grades. 



