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 



Siiigle median 

 series of four. 



Three paired. 



FIG. 21. A Phosphorescent Shrimp (Euphausia pellucida). 

 The median lamp-like phosphorescent organs are 

 numbered 3 to 6. The right side lanterns of two thoracic 

 pairs are numbered I and 2, whilst there is another pair 

 on the outer edge of the stalked eye, making ten lanterns 

 in all. g, points to the hindermost gill. Magnified 

 five diameters. 



(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 

 median row of four lanterns at the hinder part of the 

 body and three paired lanterns farther forward (Fig. 2 1 ), 

 but one kind has as many as 150 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 



