LIN y KAGE OF THE FACTOR FOR BIFID WING. 



153 



with normal red eyed long winged flies (LR) we obtain LR male 

 and female offspring. When these are interbred we obtain the 

 F'- results shown in Table III. 



TABLE III. 



RESULTS OF EXPERIMENT I., CROSSOVER. 



These results even with comparatively small numbers show 

 that the new combination BfV produced by a crossing over of 

 factors possesses approximately the same strength of coupling 

 as did the original. 



EXPERIMENT II. 



In the reciprocal cross, BfR females with LV males, the off- 

 spring consist of LR females and BfR males. In the second 

 generation the four classes of males occur in the same propor- 

 tionate numbers as those in Experiment I. 



The results to be expected are shown in Table IV. 



TABLE IV. 



To ILLUSTRATE EXPERIMENT II. 



LVX - o = LVo" 



P 1 



F 1 



BfRX - BfRX = BfR 9 

 P 1 Eggs BfRX 



BfRX - LVX = LR 9 



J (i) BfRX, (2) LVX, 

 S 1(3) BfVX, (4) LRX, 



BfRX - BfRX) 

 BfVX - BfRX j 

 LVX - BfRX 

 LRX - BfRX 



Sperm LVX, o 

 BfRX - o = BfRd" 

 ' BfRX, o 



BfRX - o = BfRo* 



LVX - o = LVd* 



BfVX - o = BfVd" 



LRX - o = LRc? 



= BfRcf 

 = LR9 



The actual results of the experiment are shown in Table V. 



TABLE V. 



RESULTS OF EXPERIMENT II. 



