ANIMAL SENSE PERCEPTIONS. 337 



are quite equal to those of a Frog.* The Norwegian fishermen 

 whitewash the rocks in the vicinity of their nets, or, where there 

 are no rocks, erect white boards, or suspend sheets, which are 

 termed " Salmon attractors," designed to represent the foam of 

 the cataract, which the Salmon is seeking to ascend. But while 

 the white colour is found attractive, the fishermen believe that 

 the fish avoids red colours, so that red clothing is carefully dis- 

 carded; and, according to Bishop Pontoppidan, even red tiles 

 have been removed for this reason from a fisherman's house.! 

 Dr. S. Dixon, a president of the Pennsylvania Academy of 

 Natural Sciences, in Philadelphia, had a large aquarium con- 

 taining goldfish and other aquatic creatures, which he was in the 

 habit of feeding every morning. During the winter, according to 

 the 'New York Tribune,' he wore dark coloured clothing, and as 

 soon as he approached the glass tank all the fish came to the 

 surface of the water looking for crumbs. Changing his clothes 

 to light-coloured fabrics the first day of May, the fish failed to 

 recognize him, and went without food for two days. In fact, we 

 cannot always conclude that the possession of eyes in some 

 fishes is an indication of sight. According to Mr. Beddard, 

 many deep-sea animals are totally blind ; yet many species found 

 in the deepest hollows of the ocean appear to have perfectly 

 normal eyes. These discrepancies were partly accounted for by 

 the theory of abyssal light. The histological study of the eyes 

 of certain deep-sea Isopoda, particularly of Serolis and Arctm'us, 

 shows, however, that the appearance of well-developed eyes was 

 often deceptive. Anyone, before having recourse to the micro- 

 tome, would assert that the deep-sea Serolis neava was as keen- 

 eyed as any species of the genus. Yet sections through the eyes 

 show that it is in a condition of degeneration ; apart from the 

 faceted cornea, there is but little of recognizable eye-structure 

 left. In S. bromleyana the eyes are well-marked, but entirely 

 devoid of pigment ; no trace of optic tissue could be found by 

 microscopical investigation. Mr. Beddard is therefore of opinion 

 that there is no need of any theory of abyssal light ; it is more 

 likely that the state of preservation of the eyes is an index of the 

 length of time that the species in question htfs been an inhabitant 



* ' Introd. Study Fishes,' p. 111. 

 t Cf. Seeley, ' Freshwater Fishes of Europe,' p. 271. 

 Zooi. 4th ser. vol. V., September^ 1901. 2 d 



