GENETIC STUDIES ON FLOUR-MOTH 423 



emerged 105 males and 120 females of typical color, and 1 male, 

 typical in color but with deformed genitalia. There also ap- 

 peared for the first time 43 black moths, 18 males and, 25 females. 

 The factor for black was probably carried as a recessive by the 

 Washington stock. 



In later generations bred from this strain there appeared moths 

 with dark mid-area. 



B. Tests for the hereditary nature of variations noted 



1. Heredity of color variations, a. Black. Summaries of all 

 the results involving black will be given here whether or not 

 other variations entered into the crosses. The recessive nature 

 of black is demonstrated without question. 



Fifteen pairs of homozygous gray by black produced 1099 

 gray. Dominance was complete. 



Nineteen pairs of heterozygous gray by black produced 494 

 gray and 429 black. The deficiency of black below the expected 

 one to one ratio is to be noted. 



Three pairs of black produced 114 black indicating that black 

 breeds true. 



Fifteen pairs and two mass cultures of heterozygous gray 

 produced 3353 gray to 969 black where 3241.5 to 1080.5 is to be 

 expected. Again the deficiency of black is to be noted. 



In cultures segregating gray and black there was considerable 

 variation in ratios. This variation was so extreme in some cases 

 that it is probable that disturbing causes such as lethal factors 

 may have been acting. 



h. Dark mid-area. It has not as yet been possible in all cases 

 to separate moths of the dark mid-area variety from type. The 

 gradation appears to be continuous. In some specimens the 

 character is very pronounced. It is carried by black where it 

 may sometimes be seen as a 'ghost pattern.' 



A mating of a black male by a dark female and three matings 

 of dark males by black females produced 126 gray and 118 black, 

 which is very close to the one to one ratio expected from heterozy- 

 gote by recessive. The grays graded from dark to type. 



