66 MENDELISM chap. 



following the results flowing from crosses between blacks 

 and whites. Experiments recently made by Staples- 

 Browne have shown that this case of reversion also can be 

 readily interpreted in Mendelian terms. In these ex- 

 Black Barb x White Fantail Black Barb x Spot i 

 Dark x Dark 



Among the offspring one very similar 

 to the wild blue rock. 



periments the cross was made between black barbs and 

 white fantails. The Fi birds were all black with some 

 white splashes, evidently due to a separate factor intro- 

 duced by the fantail. On breeding these blacks to- 

 gether they gave an F2 generation, consisting of blacks 



Black y White 

 Barb | Fantail 



Black y Black 



(White Splashed) 



■y 



(White Splashed) 



1 1 



Black Black Blue Blue White 



White Splashed) (White Splashed) 



<■ -■ 



(9) <3) (4) 



(with or without white splashes), blues (with or without 

 white splashes), and whites in the ratio 9:3:4. The 

 factors concerned are colour (C), in the absence of 



^ This is an almost white bird, the colour being confined to the tail 

 and the characteristic spot on the head. 



