354 THE BEAUTIES OF NATURE CHAP. 



organs flash out must present a very remark- 

 able appearance. 



We have still much to learn as to the 

 structure and functions of these organs, but 

 there are cases in which their use can be 

 surmised with some probability. The light- 

 is evidently under the will of the fish. 1 It is 

 easy to imagine a Photichthys (Light Fish) 

 swimming in the black depths of the Ocean, 

 suddenly flashing out light from its luminous 

 organs, and thus bringing into view any prey 

 which may be near ; while, if danger is dis- 

 closed, the light is again at once extinguished. 

 It may be observed that the largest of these 

 organs is in this species situated just under 

 the eye, so that the fish is actually provided 

 with a bull's eye lantern. In other cases the 

 light may rather serve as a defence, some 

 having, as, for instance, in the genus Scope- 

 lus, a pair of large ones in the tail, so that 

 " a strong ray of light shot forth from the 

 stern-chaser may dazzle and frighten an 

 enemy." 



In other cases they appear to serve as 



1 Gunther, History of Fishes. 



