40 TYPES OF MENDELIAN HEREDITY 
not occur, but if the flies are reared on dry food they 
are normal from the beginning. The character is a 
sex linked dominant, as shown by the following 
crosses. When an abnormal male is bred to a normal 
(wild) female, the daughters are abnormal (if the 
Fic. 19.—Mutant type called Abnormal Abdomen of Drosophila 
ampelophila (the wings have been cut off); ais female; b, male; c, female 
that approaches the normal type. 
food is moist), but all the sons are normal. If the 
medium is dry, however, both the daughters and the 
sons alikearenormal. But these normal F, daughters 
will produce the expected abnormal offspring if the 
conditions are suitable, and these offspring are just as 
