BRISTLE INHERITANCE IN DROSOPHILA 



113 



means. This fact, together with the warmth of the constant 

 temperature room, renders the means in this period (generations 

 32 to 49) obviously uncomparable with the means in earher 



MEANS 



, MALES 



PARENTS Sir 



GENERATIONS 



_J \ \ \ L 



EXTRA BRISTLES 



SONS StNGLELfNE 



SONS TOTALGENERATIONS 



J \ I I I 



14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 



MEANS 



FEMALES 



EXTRA BRISTLES 



TOTAL GENERATIONS 



GENERATIONS 



J \ \ L 



14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 



B 



Fig. 2 Means in the line of single families compared with means in the total 

 generations. Since there was only one family each in generations 24, 25 and 26 

 there is only one curve through these generations. In 'A' the sons are compared 

 in 'B' the daughters are compared. The mean grade of the two parents in each 

 generation of the single line is shown with the 'A' curves. When single families 

 are examined it is found that fluctuations in the parental grades are not accom- 

 panied by corresponding changes in ths average grades of the offspring. 



