86 THE INFLUENCE OF INANIMATE SURROUNDINGS. 



animals, at least among the insects, to whom this light serves 

 as a guide by which to find each other, as in the male and 

 female Lampyris ; and such a light would undoubtedly be 

 equally serviceable at the bottom of the sea to all the animals, 

 those preying as well as those preyed upon ; for without light, 

 escape and pursuit must alike depend wholly on accident, and 

 the remarkable fact that the eyes of deep-sea creatures are not 

 always and completely abortive would thus be accounted for, as 

 far as is possible perhaps on the whole. 



One pressing difficulty, however, remains. We know that 

 blind animals, as well as those that can see, exist at the bottom 

 of the ocean, while their nearest allies at the surface have well- 

 developed eyes. Why have the deep-sea species lost their eyes 1 

 The same question confronted us with regard to the cavern 

 animals, and could not be answered even hypothetically. With 

 regard to the deep-sea animals more accurately deep-sea 

 fishes Dr. Giinther, in London, has lately made a remarkable 

 attempt to explain the case, and although his views are as yet 

 unpublished he has been so amiable as to communicate to me 

 their most essential features. lie has found, particitlarly 

 among the deep-sea fishes brought back by the ' Challenger ' 

 expedition, certain very peculiar forms, blind and not-blind ; 

 the latter have exceptionally large eyes, which seem espe- 

 cially fitted to absorb pale phosphoric light in large quantities, 

 while the blind fish, on the other hand, are distinguished by 

 peculiar and sometimes colossal organs on the head, which have 

 quite displaced the eyes, and which exhibit a very singular 

 structure, that justifies us, according to Dr. Giinther, in assuming 

 that they are peculiarly and strongly developed phosphorescent 

 organs. 23 Now these, in Dr. Giinther's opinion, may very 

 possibly be used by their owner, as torches and other lights are 

 used by fishermen, to entice and catch other fish. But, just as 

 pirates are attracted by the lights of fishermen and guided to 

 their victims, so the light which these blind fish carry in the 

 two lanterns on their head to attract their prey may be a 

 beacon to their enemies, and at the same time be of assistance 

 to such fish as can see, in their movements generally. Thus 

 we can well understand that in the struggle for existence, which 



