58 THE WONDER OF LIFE 



course to the vicissitudes of day and night (unknown in 

 the Deep Sea) and of the seasons (there is eternal winter 

 in the Deep Sea). The vicissitudes of temperature are 

 much more marked than in the Open Sea. With its tides 

 and storms and floods, the shore-area is on the whole very 

 difficult and ' trying '. Its tenants must be familiar with 

 what has been called ' the discipline of dislodgment'. 

 We may refer to the wreckage of life seen in the jetsam 

 after a heavy storm, to the effects of a very hard winter 

 on the shore population the following summer, and to the 

 long-lasting effects of the last eruption of Vesuvius on the 

 fine littoral fauna of the Bay of Naples. 



There are, it is true, circumstances in which the life of 

 the shore is sheltered from much of the mercilessness of 

 the physical forces we are thinking of the deep holes whose 

 sides are unsecured except by the severest storms, the 

 sunny shallows on the inner side of the breakwater formed 

 by a barrier coral-reef, the stretches of lagoon protected 

 by a mangrove belt a mile broad, and the great mud-line 

 itself where wave-action has ceased. These are instances 

 of conditions where delicate organisms may live a sheltered 

 life even within the littoral area, but in most cases the 

 reverse is much nearer the truth. The shore is a hard 

 school where lessons are driven home with blows and where 

 risks are continuous. It furnishes many illustrations con- 

 firming Tennyson's conclusion in regard to one aspect of 

 organic Nature : 



That life is not as idle ore 

 But iron dug from central gloom 

 And heated hot with burning fears 

 And dipped in baths of hissing tears 

 And battered by the shocks of doom 

 To shape and use. 



