THE NATURAL HISTORY EXCURSION 143 



sists of eggs. There are many thousands of them, and in 

 a fresh herring you will notice how sticky they are. They 

 are shed into the sea, fall to the bottom, and adhere to the 

 stones. If the eggs are squeezed from a ripe female into 

 a vessel of water, they stick to the bottom, and in half an 

 hour are so firmly attached that the vessel may be turned 

 upside down without the eggs falling out. Herring-eggs 

 are saved by their density and their stickiness from one 

 source of danger ; they cannot be swept by currents into 

 unsuitable hatching-places. They escape also vast numbers 

 of voracious animals, mostly fishes, which are always 

 searching the surface of the sea for something eatable. 

 But they escape one danger only to fall into another. The 

 bottom-feeding flat-fishes are on the look-out for herring- 

 eggs, and often cram their stomachs with them. 



The young herring has enormous eyes and a very slender 

 body, from which at first a yolk bag protrudes. Until it 

 has attained the age of three months, and a length of about 

 two inches, it has no scales, and the body has not the thin 

 flat shape which it afterwards acquires. Herrings of from 

 three to six months are called " whitebait." They are 

 fond of one another's company in all stages of growth, and 

 swim about in shoals, approaching the shore at the spawn- 

 ing-times, which are spring and autumn. In order to 

 obtain protected spots for their eggs, they will enter long 

 narrow inlets where the water is almost fresh. The 

 salmon goes farther still, and ascends rivers far beyond 

 the reach of the tide, in order to spawn. 



Sprats, shads and pilchards are all so like herrings that 

 they can only be distinguished from them by close observa- 

 tion. Sardines are young pilchards. 



XXVIII. THE NATURAL HISTORY 

 EXCURSION. 



The natural history excursion, which ought to be a first- 

 rate teaching expedient, often fails to answer its purpose 



