ioo THE WORLD'S LUMBER ROOM. 



out of place by the tender blades of grass growing between 

 them ; and Canon Kingsley mentions having seen a large 

 flat stone raised up in a single night by the growth of a crop 

 of tiny mushrooms. 



Then, again, we read of a nut tree springing up in the 

 centre hole of a disused mill-stone, whose stem grew and 

 increased in size until it entirely filled the hole ; whereupon 

 it gradually raised the stone from the ground, until the huge 

 mass, some five or six feet in diameter, was lifted up eight 

 inches all round, and was supported in the air by the stem 

 only. The tree attained the height of twenty-five feet, bore 

 excellent fruit, and was killed at last, not by the weight ot 

 the stone, but by the tightness of its embrace, which stopped 

 the flow of sap. This is certainly "a striking example 

 of the tremendous powers of Nature ; " and since trees and 

 plants grow as vigorously downwards as upwards, their roots 

 must certainly help to break up the rock, not only by 

 causing decomposition, but by forcing their way into joints 

 and cracks and then gradually widening them. The island 

 of Aldabra, north-west of Madagascar, for instance, is 

 being reduced and destroyed by the silent inroads of the 

 mangroves, which grow along the base of the cliffs and have 

 eaten their way into the rock in so many directions that 

 the island is completely riddled by creeks of their making. 



But we must now pass on to more intelligent burrowers, 

 foremost among whom comes the great army of worms. 



It has been calculated that there are as many as 53,767 

 worms in each acre of garden ground, and about half that 

 number in cornfields. Nine burrows, and sometimes many 

 more, are usually found in two square feet of garden soil j 



