CHAPTER XXIII 



FISHES. THE MOST UNIFORMLY AND NEARLY INVARIABLY COUNTER SHADED 

 OF ANIMALS. THEIR COLORS AND PATTERNS. OTHER MARINE ANIMALS 



'HOUGH my father and I know next to nothing about fishes from the 



A standpoint of systematic science, we have yet gathered, from lifelong 

 observation of them in their element, in market stalls, in museums, and (pic- 

 tured) in books, a trustworthy general estimate of the main characteristics 

 and prevalences of their disguising coloration. As a class, they are in some 

 respects the crowning vindication, or rather natural demonstration, of the 

 great law of obliterative counter shading. For while in each of the classes of 

 vertebrate land animals the exceptions to the employment of this principle 

 are, in the aggregate, many, despite the vast preponderance of the species on 

 which it is used, among fishes the exceptions are so extremely rare as scarcely 

 to count at all. This is true, at least, of the fishes that live within the reach 

 of daylight, as do almost all the kinds familiarly known to man. Cave fishes, 

 living in absolute darkness, are blind and colorless — dull white, i. e., simple 

 fish-flesh color, all over. Deep-sea fishes, though they live in perpetual night, 

 are as a rule neither blind nor wholly without superficial color. They are 

 sometimes whitish all over, like the cave fishes, but oftener monochrome 

 gray or brown, without special shading, though sometimes marked with red. 

 Thus there can be little doubt that despite the total want of daylight in the 

 waters they inhabit, they habitually see and are seenl The solution of this 

 enigma is the fact that the fishes and other deep-sea animals make and emit 

 phosphorescent light. How generally and how largely this is accomplished 

 we can judge only by the physical evidence furnished by the fishes' eyes and 

 surface-colors. But it goes almost without saying that this 'home-made' (!) 



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