22 ANIMAL LIFE UNDER WATER 



would give a quick turn to seize it, and there was 

 a momentary " flash." If the pike was on the 

 feed he would show his agitation at once by a 

 glint of the eye and by erecting his dorsal fin, 

 but by no other movement would the predatory 

 fish show that he had detected the presence of 

 his prey. A second "flash," and the pike raised 

 himself on his paired fins, straightened his 

 back, and, rigid with excitement, slowly glided 

 towards the patch. If the dace remained until 

 the pike was within striking distance, there was 

 a sudden rush, a swirl, and the small fish was 

 seized by the middle, turned and swallowed. 



The pike was on the look-out for food, yet 

 the same reflection of colour and counter- 

 shading which made it difficult for the human 

 eye to detect the dace concealed it from the 

 pike, and the same momentary " flash " which 

 was apparent to the human eye was an indication 

 to the pike of the presence of its prey. 



Whether fish appreciate colour in the same 

 way as we do has always been a rife subject for 

 discussion. 



I argue that a great many forms of fish food 

 are concealed from the human eye by colour 

 schemes; the same food is undoubtedly con- 



