We'ntworth of Kansas Agricultural Experiment 

 Station reports, the herd Ayrshire bull being a dark maho- 

 gany and white in color, popularly known as black, that 

 (1) crosses with red females produced all black males and 

 all red females; (2) the Fo generation shows a black male 

 and a black female; (3) crosses with black females pro- 

 duced one black male and three black females; (4) cross- 

 ing a similar black female with a black male (heterozygous) 

 gave 2 black males, 2 black females, and one red female. 



There is here evidence of color being linked up with sex , 



(2) Female Heterozygous for Sex Factor 



The WZ type of inheritance 

 Hybrids of Abraxas Moths. 



Mention has already been made of the probability 

 that the females of Abraxas are heterozygous and the males 

 homoyzgous with regard to the sex factor, 



Theresultsof crossing A. grossulariata and A. laciicolor, 

 a pale variety, by Doncaster and Raynor are explained on 

 two assumptions: 



(1) The female is heterozygous for sex, femaleness 

 being dominant, and the male homozygous re- 

 cessive;- 



(2) The factor for color for grossulariata is dominant . 

 The gametic formulae for the crossings are given below : 



C = dominant foctor for color (grossulariata) 



c = recessive factor for color (lacticolor) 

 WZ = sex factors in female (two kinds of ova) 

 WW = Sex factors in male (one kind of sperm) 



Case I. Grossulariata (male) x laciicolor (female). 



The male gametes are all of one kind-CW, while^the 

 female gametes are of two kinds-cW and cZ. 



The matings may be represented as follows: — 



CW CW = male gametes 



Female 

 Gametes 



cW 



i.e. All grossulariata, half being male. 



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