NATURAL HISTORY STUDIES 



than the whole body, probing a long distance ahead, 

 so that the animal gropes its way as a blind man 

 does with his stick. Many of the long legs of 

 crustaceans bear tactile bristles, and many of the 

 fishes have long slender and sensitive barbules 

 stretching backwards from the chin or from the 

 fins. 



Problems. There are many unsolved problems in 

 the Deep Sea, and one of these is the frequent 

 "phosphorescence." It is seen in animals of high 

 and low degree ; it is exhibited by fixed animals and 

 by free swimmers ; it is produced by a great variety 

 of organs ; and these are sometimes situated on 

 most extraordinary places near the end of the 

 tail, on the tip of a long flexible rod, inside the gill- 

 chamber of a crustacean. It is so common that it 

 surely has some meaning. 



May it be sometimes a lure, attracting victims, 

 who come like moths to the candle ? Is it some- 

 times an advertisement on the part of unpalatable 

 creatures, warning off intruders and molesters, as 

 the rattlesnake does with its rattle ? Does it 

 sometimes serve as a lantern, guiding the active 

 animal to its prey ? Of course that would not apply 

 to cases where the light is at the hind end ! Does it 

 serve in some cases as a " recognition mark," 

 enabling those of the same kin to know one another ? 

 The light-production of Deep-Sea animals is still 

 in great part an unsolved problem. 



Another difficulty is raised by the fact that there 

 is so much colour in Deep-Sea animals. What can 

 be the use of that in an abode of darkness ? There 



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