ORIGIN OF MUTANT CHARACTERS 61 



They behave as a pair of contrasted elements, that are 

 separated in the hybrid at the maturation of the eggs and 

 sperm. 



LACTICOLOR 9 01 



GR0SSULAR1ATA d LL 



O © GERM CELLS © 



CROSSULAR^TA 9 OL 



GR0SSULAR1ATA d 1 L 



© © CERM CELLS . © © 



O ©' 



LACTICOLOR 9 01 



O © 



GR0SSULARIATA90L 



© © 



CROSSULARlATAdLl 



© © 



CR05SULARIATA d LL 



Fig. 39. 

 Diagram showing a cross between the light-colored type (lacti- 

 color) of Abraxas and the common or dark type (grossulariata). 

 The sex-chromosome carrying the gene for dark color is here indi- 

 cated by the circle enclosing L, that for light color by the circle 

 with 1. The open circle (without an included letter) stands for 

 the W-chromosome that is confined to the females. 



It is important to observe that the theory does not 

 state that the white-eyed gene alone produces white eyes. 

 It states, only, that a change took place in some part of 

 the original material, and in consequence of this single 

 change, the material, taken as a whole, now gives rise to 



