GLOW-WORMS, TERMITES, SHELLS 223 



this mechanism is dependent in part on external 

 stimuli of which one of the chief is moisture and one 

 of the least important is the absence of light. 



Phosphorescent animals in general live in close 

 association with moisture. The luminous inhabitants 

 of the sea exemplify this. Not only many of the 

 species that live at great depths, but the little globular 

 Noctiluca that stain the surface of the ocean with 

 patches of rusty red, are brilliantly phosphorescent. 

 The glow of the Noctiluca resembles that of the 

 Lampyris, the light being a similar shade of green. 

 It is specially attractive on a summer night in the 

 Persian Gulf. The surface of the ocean gleams with 

 light. Each little ripple is an evanescent glowing 

 gem, one amongst millions in the quivering sea. 

 From the bows of a ship two curling waves diverge, 

 displaying first their gleaming crests, and then, spread- 

 ing into a sheet of foam, they shine like burnished 

 silver. Porpoises roll in rivers of light, and flying-fish, 

 in glistening streaks, flash through the dark sky. The 

 phosphorescence of animals is as beautiful as its origin 

 and object is unknown. 



Glow-worms have long been known to feed on 

 snails. I witnessed the attack of a large glow-worm 

 on its prey. The snail was crawling over the ground, 

 and the Lampyris, coming up behind it, climbed on 

 to the shell and remained seated on the summit while 

 the snail moved onwards. The glow-worm then 

 gradually altered its seat on the snail's back ; it 

 methodically worked itself into a position suitable 

 for attack until its head projected forward over the 

 anterior edge of the shell. The beetle was now 

 firmly fixed. By means of its hind suckers it had a 



