286 THE WONDERS OF INSTINCT 



on the back and not under the belly; otherwise the light 

 is hidden under a bushel. 



The anomaly is corrected in a very ingenious fashion, 

 for every female has her little wiles of coquetry. At 

 nightfall, every evening, my caged captives make for the . 

 tuft of thyme with which I have thoughtfully furnished 

 the prison and climb to the top of the upper branches, 

 those most in sight. Here, instead of keeping quiet, as 

 they did at the foot of the bush just now, they indulge in 

 violent exercises, twist the tip of their very flexible 

 abdomen, turn it to one side, turn it to the other, jerk it 

 in every direction. In this way, the searchlight cannot 

 fail to gleam, at one moment or another, before the eyes 

 of every male who goes a-wooing in the neighborhood, 

 whether on the ground or in the air. 



It is very like the working of a revolving mirror used 

 in catching Larks. If stationary, the little contrivance 

 would leave the bird indifferent; turning and breaking 

 up its light in rapid flashes, it excites it. 



While the female Glow-worm has her tricks for sum- 

 moning her swains, the male, on his side is provided 

 with an optical apparatus suited to catch from afar the 

 least reflection of the calling signal. His corselet ex- 

 pands into a shield and overlaps his head considerably 

 in the form of a peaked cap or a shade, the object of 

 which appears to be to limit the field of vision and con- 

 centrate the view upon the luminous speck to be discerned. 

 Under this arch are the two eyes, which are relatively 

 enormous, exceedingly convex, shaped like a skull-cap 

 and contiguous to the extent of leaving only a narrow 



