THE INVISIBLE FOOD OF FISH 243 



fish, even supposing these could be found in sufficient 

 numbers to form food for the numberless herrings. 

 The rapidity and order of their movements make 

 it equally unlikely that they should stop to chew 

 and browse on vegetables, even when arrived in the 

 shallow seas where seaweeds grow. It was just possible 

 that previous to spawning the fish could for a time 

 abstain from food. But it was equally certain that 

 after spawning their numbers were the same, and 

 that they must require food, and that in large 

 quantities, in an area no greater than that occupied 

 by the herring or pilchard shoal, so long as the 

 fish remained in that formation. The explanation 

 is that the microscopic creatures which are in parts 

 of the Atlantic massed so thickly in the water as 

 to discolour the surface, and give abundant food 

 for the whale, are present, not so thickly, but in 

 numbers comparable to the motes in the air, in all 

 parts of the sea. For the purposes of the herring 

 and the pilchard, and countless other vertebrate fish 

 shell fish, and zoophytes, the upper waters of the 

 sea are in fact a nutritive soup, teeming with food 

 exactly suited to their needs. These microscopic 

 creatures are the basis of all the larger life of the 

 ocean, and in a great degree of the growth and 

 increase of fresh water fishes. Some of these tiny 

 creatures are water-fleas, others like carapaced shrimps, 



