Fig. 10. 



The inheritance of four linked, recessive characters, vis., black 

 body color, purple eyes, vestigial wings, and speck, versus their 

 normal allelomorphs of the wild type fly. The F x male is "back- 

 crossed" to a female of the multiple recessive stock, giving in 

 the second generation (shown below) only the two grand parental 

 combinations. 



