INHERITANCE OF A MACULA MUTATION. 269 



heterozygous, spotted (Mm) females and 483 heterozygous, 

 spotted (Mm) males. This test further shows the dominance of 

 the spotted trait to the normal. Furthermore this experiment, 

 when compared with the previous one, proves that the character 

 is not sex-linked. Table II. gives the data. 



The third test concerned heterozygous, spotted (Mm) females 

 and heterozygous, spotted (Mm) males. The F 2 progeny from 

 43 FI single pairs totaled 1,079 spotted (MM, Mm, mM, mm) 

 females, 994 spotted (MM, Mm, mM) males, and 323 non- 

 spotted (mm) males. The result approaches a 4:3:1 sex- 

 limited ratio, which shows that the spotted females appear 

 identical, and that macula is dominant to normal. This data is 

 tabulated in Table III. 



The fourth experiment is a back cross with the FI hybrids, 

 (Mm), heterozygous insects, and the normal type (mm) weevils. 

 The parents were heterozygous, spotted (Mm) females and 

 homozygous, non-spotted (mm) males. From 41 single pair 

 matings 1,375 spotted (Mm, mm) females, 697 heterozygous, 

 spotted (Mm) males, and 658 homozygous, non-spotted (mm) 

 males, were obtained. The ratio, therefore, approximates a 

 sex-limited 2:1 : I. This result indicates further that normal 

 spotting is recessive to macula. The data is listed in Table IV. 



The fifth experiment was another back-cross test, the reciprocal 

 of the previous one. Homozygous, normal, spotted (mm) fe- 

 males were mated with heterozygous spotted (Mm) males. 

 From the 43 different pairs a total of 1,415 spotted (Mm, mm) 

 females, 786 heterozygous spotted (Mm) males and 798 homo- 

 zygous non-spotted (mm) males were obtained. This gave a 

 2 : I : i sex-limited ratio, or actually a I : I ratio, since the 

 females appeared alike. Spotting is dominant to the normal 

 type. Complete information is found in Table Y. 



In the sixth test heterozygous spotted (Mm) females and 

 homozygous spotted (MM) males were used. The offspring 

 from 26 separate pairs totaled 701 spotted (MM, Mm) females 

 and 654 spotted (MM, Mm) males. This demonstrates the 

 dominance of the macula character to its recessive normal trait, 

 spotted females and non-spotted males. This data is compiled 

 in Table 6. 



