150 THE GREENWOOD TREE. 



stronger bushes or trees, which they often choke and 

 starve by monopolizing at last all the available carbon 

 and sunlight. And so throughout ; the struggle for life 

 goes on just as ceaselessly and truly among these 

 unconscious combatants as among the lions and tigers of 

 the tropical jungle, or among the human serfs of the 

 overstocked market. 



An ounce of example, they say, is worth a pound of 

 precept. So a single concrete case of a fierce vegetable 

 campaign now actually in progress over all Northern 

 Europe may help to make my meaning a trifle clearer. 

 Till very lately the forests of the north were largely 

 composed in places of the light and airy silver birches. 

 But with the gradual amelioration of the climate of our 

 continent, which has been going on for several centuries, 

 the beech, a more southern type of tree, has begun to 

 spread slowly though surely northward. Now, beeches 

 are greedy trees, of very dense and compact foliage ; 

 nothing else can grow beneath their thick shade, where 

 once they have gained a foothold ; and the seedlings of 

 the silver birch stand no chance at all in the 

 struggle for life against the serried leaves of their 

 formidable rivals. The beech literally eats them out of 

 house and home ; and the consequence is that the thick 

 and ruthless southern tree is at this very moment 

 gradually superseding over vast tracts of country its 

 more graceful and beautiful, but far less voracious 

 competitor. 



