78 THE STORY OF FISH LIFE. 



some of which would tend to produce more dark 

 pigment above than below, and this would lay the 

 foundation for natural selection to work upon. 

 Natural selection would operate by render- 

 ing those fishes with darker backs and lighter 

 underparts less conspicuous than their fellows, 

 who would sooner fall a prey to other fish from 

 below, and fish-eating birds and mammals from 

 above. 



We have done no more than touch upon the 

 fringe of this question in this chapter. It is one 

 that would well repay further study, for there 

 are many puzzles to be solved. 



CHAPTEE VIII. 



HOW FISHES FEED. 



ALL living things must eat, and whether it be 

 dirt the dust of the earth mingled with rain- 

 drops, such as forms the diet of an earthworm, 

 or whether it be of the dainty dishes set before 

 the king, that which we eat must contain some 

 nourishing properties. But what is good to eat 

 and what is hurtful is knowledge which comes of 

 experience. Knowledge bought sometimes at a 

 great price even the death of the purchaser. 

 The pages of the history of mankind furnish 

 us with many lessons in the dangers as well as 

 the delights of Beating. 



Sight, smell, taste and memory are the council 

 board which determine the menu for the higher 



