THE Ml TAT ED GE VE 



II 



-cries of multiple allelomorphs was reproduced I hrougfa treal menl 

 of a member of the series. There is first the work of Zeleny and 

 Krafka oe the Bar-eye Beries in Drosophila, Seyster (1019; 

 and Krafka (1920) had shown thai the size of the eye and the 



number Of ommatidia in Bar-eye Drosophila vary with the 

 1500 



15 20 25 30 



Temperature in degrees C . 



Fig. 2. — Data for homozygous females of various stocks of the Bar-series in 

 Drosophila plotted semilogarithmically. 1, Wild type full; l'. reverted full; 

 3, unselected Bar; 4 6, different low selected Bar; 7-9, different Ultrabar. 

 {^rom ITrsh, L930, ./. Exp. ZooL. 57, Fig. 1.) 



temperature at which the larvae are developed. < >n the average 

 an increase of 1°C. produces ;i decrease of about 10 per cent in 

 ommatidia] number. In Ultrabar, the change is aboul 8 per cent ; 

 tui- Wild eye t he efYect is about 2 1 ■> per cent. In flies heterozygous 

 for Ultrabar ;iii<1 Wild, tin- percentage is equal to that ni Ultrabar. 

 (We shall return to this point in the chapter on dominance.) 



More exact measurements were taken by Luce (1926) and 

 Driver (1920, 1931) for different temperature- and alleles. A- an 



