WHAT THE FISHES SEE 



struck by the expression of their eyes, or rather the 

 absence of all expression. These eyes, which are some- 

 times huge and take up the greater part of the cheeks, 

 have nothing to show but a torpid and empty depth, 

 like those of some blind men who, by the very wide- 

 openness of their expressionless eyes, give evidence of 

 the insensitiveness of the retina. They look as if they 

 did not see at all. In these fish the enormous eyes 

 are there, but they fulfil no function. They are of no 

 use for the purpose which one expects of them, but 

 they have their place in the structure of the head; 

 they are a part of its architecture, and in that respect 

 contribute their share to the organic shape, but, as 

 regards visual sensation, they contribute nothing. In 

 their dark environment, in that vast mass of water 

 which so soon puts out the lights of animals with 

 sight, there can be no part for them to play. These 

 fish must have other sensitivities to guide them, other 

 mechanisms, and these are taste and vibration. 



In spite of apparent resemblances, there is con- 

 siderable diversity in this respect. If, save for a few 

 exceptions, all fishes have their eyes similarly situated 

 and of the same conformation, showing no more than 

 differences of size, there are marked contrasts to be 

 observed in the manner of their employment. For 

 that matter, we find such contrasts on land. A bird 

 of prey, several hundred feet up in the air, can, with 

 its keen vision, see a rabbit in a field, whereas the 

 rabbit finds this distance too great for its visual equip- 

 ment and does not see the bird. Hence the bird is 

 able to prepare its swoop, pounce upon its victim, and 

 grasp it in its claws before that victim has a chance 

 to escape. When the rabbit does espy its danger, it 

 is too late. 



However, both sorts of eyes, those of vertebrates in 

 the air and those of the water vertebrates, have prac- 

 tically the same structure; the same parts work in the 

 same way. This difference in the keenness of vision 

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