WHAT THE FISHES SEE 



words about those who do not believe: " Eyes have 

 they and see not "? In spite of the apparent paradox 

 of the answer, we must admit that it is true of the 

 species which live in the dark regions of the world 

 of waters, those zones of complete darkness which, as 

 a matter of fact, make up its greatest part. As for the 

 fishes which are nearest to ourselves, we cannot, 

 indeed, flatly deny that they have sight, but we must 

 allow that they see only a little. On the other hand, 

 this " little ", so far as they are concerned, is relative. 

 Our own vision is more perfect, and we can use the 

 expression only in relation to our own better capacity 

 for seeing. The " little " is as much as the fish needs. 

 Its feeble visual capacity is sufficient for the life it 

 ordinarily leads in the waters. 



We use the word " vision " for a complex phenom- 

 enon in which we associate comprehensively several 

 partial sensations which, although they are all visual, 

 are practically independent. When we perceive an 

 object, we perceive its contours, its colours, its move- 

 ments; the image of all this is projected upon our 

 retina, and the retina is sufficiently perfect to accept it 

 as a whole and make it sensible to us, making everything 

 perceptible at the same time. But the three sensations 

 are actually distinct, none the less. We connect them 

 up, we make a unity of this visual triad, but each has 

 its own particular manner of working. We may 

 presume that there are retinas in which these sensations 

 are not present as they are in our own and in those of 

 a good number of land vertebrates, retinas where they 

 are perhaps more separate, in which one grows weaker 

 while the others remain unaffected, or do not weaken 

 to the same extent. So it is with fishes. 



Their eye produces a blurred image, certainly, but 

 this is true only as regards forms and contours, because 

 the image is imperfectly produced. On the other 

 hand, the relatively large proportion of pigment in 

 the retina causes it to be easily influenced by brightness 

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