GENE MUTATIONS 



CHEESE, ch (body). This mutant appeared in the 

 summer of 1934 in the offspring of an X-rayed 

 female (dosage about 4500 R units) (P. W. Whit- 

 ing, 1935b). Cheese is a pale, opaque, green- 

 ish-yellow, and the color is especially notice- 

 able in the head. It was discarded soon after 

 its occurrence. 



SILVER, si (body). This mutant appeared in the 

 summer of 1934 in the offspring of an X-rayed 

 female (dosage about 4500 R units). In thisi 

 mutant type pigmentation is apparently arrested 

 since the body fails to darken. This mutant, 

 has been discarded. 



Variation in general body pigmentation is) 

 controlled largely by temperature, but influ- 

 ence of hereditary factors is also obvious. 

 V/hen reared at 30° C, the wasps show differ- 

 ences in color of the mesosternum, 



SOOTY, s (mesosternum). A factor for sooty 

 mesosternum was shown (P. W. Whiting, 1926a) toj 

 be linked with defective (see wing mutations). 

 This mutant has been discarded. 



A few mutations affecting body size and 

 shape have occurred. 



MINIATURE, m (body). One mutation for bouy 

 size occurred in March, 1928. Six sons from a 

 female mated to an X-rayed male (dosage about 

 2950 R units) appeared with body size much re- 

 duced. The primary wing is less rounded on the 

 costal margin. The antennae are shortened, 

 both by shortening of the segments and by re- 

 duction of their number. There is also some 

 irregularity in the way the segments are set 



37 



