154 



DIVERSIONS OF A NATURALIST 



oxidized) by the sea-water, the chemical action setting 

 up light-vibrations, but not the usual excess of heat- 

 vibrations to which we are accustomed when light 

 accompanies ordinary " burning " or " combustion." 



Other crustaceans of several kinds, of an inch and 

 more in length — transparent, delicate creatures, re- 

 sembling small prawns in appearance — also produce 

 light. Some of them are known by names referring to 

 this fact, such as Lucifer (light-bearer) and Nyctiphanes 



Fig. 21. — A Phosphorescent Shrimp (Euphausia pellucida). 

 The lamp-like phosphorescent organs are numbered 

 I to 6. There is another on the outer edge of the 

 stalked eye, making seven in all on each side of the 

 animal. ^, points to the hindermost gill, enlarged. 



(night-shiner). They possess special lantern-like knobs 

 scattered about on the body, which have transparent 

 lenses, and resemble small bull's-eye lanterns. Some 

 have a row of seven lanterns on each side of the body 

 (Fig. 2 i), but one kind has as many as i 50 dotted about. 

 These lanterns were only a few years ago thought to 

 be eyes, and their elaborate microscopic structure was 

 described as that of an eye. Of course, this was due to 

 the fact that dead preserved specimens were studied, and 

 not the living animal. Some twenty years ago I 

 witnessed a most impressive exhibition of these phos- 

 phorescent shrimps at the house of my friend Sir John 



