GENE MUTATIONS 



lar. The trait grades into type. It was im- 

 possible to obtain offspring from female spread. 

 Males are of normal fertility. (Discarded) 



NOTCH, No (wings). Notch is a mutation affect- 

 ing the outline of the wing. It appeared in 

 April, 1930, in the progeny of a type female by 

 a tapering male (see antennal mutations). Notch 

 exerts its effect on the margin of either pri- 

 mary or secondary wings; the notches may be 

 terminal or lateral. The first branch of the 

 radius vein is shortened, causing the usual 

 rounded lobe of the wing to be notched; how- 

 ever, there is much irregularity and asymmetry 

 in the expression of this factor. Notch does 

 not breed true, and it is very likely that there 

 are more factors than one involved. In many 

 cases the trait acts like a dominant lethal. 

 (Discarded) 



SHOT-VEINS, sv (veins). Shot-veins is a semi- 

 dominant factor that arose simultaneously in 

 three different lines after extreme heat treat- 

 ment of larvae. It causes veins of the wings) 

 to be broken and distorted (Fig. 7). This mu- 

 tant was found in August, 1930. Shot-vein stock 

 has proved to be fully fertile and stable. In 

 connection with studies of linkage made in 

 1931, shot-veins v/as crossed to white eyes, and 

 the Fl females bred as virgins. The double re- 

 cessive, shot-veins and v/hite eyes, showed a 

 mottling of red spots in the posterior ventral 

 region of the compound eye. It has since been 

 observed from very large numbers that these 

 spots are present in both eyes of all white- 

 eyed individuals with shot-veins. Their dis- 



«y 



