152 



COLEOPTERA. 



of secreting a substance which becomes luminous 

 when acted upon by oxygen. The supply of this gas 

 is probably provided by the trachccne, if this theory is 



correct. Dimmock has observed that when one sex of 

 any species of Lampyridse is more luminous than the 

 other, the less luminous sex has, as a rule, the best 

 developed eyes. This fact may throw some light on 

 the origin of the phenomenon of phosphorescence. 

 The male and female of the species mentioned above 

 have wings and elytra, but the females of some genera 

 in this family do not possess these organs, and they 

 are commonly called "glow-worms." Fig. 92, c, rep- 

 resents a glow-worm of the genus Lampyris." The 

 females of such species do not develop beyond a 

 modified larval stage. While the reproductive system 

 fills out its cycle of growth and development, the 



