30 



HEREDITY AND SEX 



and remain there without glowing. A male passes by 

 and flashes his Hght ; the female flashes back. In- 

 stantly he turns in his course to the spot whence the 

 signal came and alights. He signals again. She re- 

 plies. He ascends the blade, and if he cannot find her, 

 he signals again and she responds. The signals con- 



FiG. 17. — Male and female Hercules 

 beetle. (After Kingsley.) 



tinue until the female is found, and the drama of sex 

 is finished. 



Mast has recently shown that the female firefly does 

 more than simply respond to the signal of the male. 

 If a male flies above and to the right of the female, she 

 bends her abdomen so that its ventral surface is turned 

 upward and to the right. If the male is above and to 

 the left, the light is turned in this direction. If the male 



