THE METHOD OF EXPERIMENTAL BREEDING 473 



I 



Fig. 251. — Results of crossing a white-eyed female Drosophila with a red-eyed 

 male (c/. Fig. 258, p. 482). The X-chromosomes and the symbols for the genes 

 are explained in the legend of Fig. 250, which shows the reciprocal of this cross. 



(From Morgan, et al., "The Mechanism of Mendelian Heredity," copyright, 1922, by 

 Henry Holt and Co., reprinted by permission.) 



