THE ORIGIN OF THE HAMMOCKS 207 



I have called the live oak our stateliest tree, the 

 Achilles of the hammocks, and like that hero it 

 has a vulnerable spot. When it has finished its 

 pioneer work, and the floor of the forest has be- 

 come a deep bed of leaf mold; when there is no 

 longer danger that the center of the forest will 

 be devastated by fire, a final immigration of 

 strictly tropical trees arrives. These last arrivals 

 cannot live in the fire zone and can only grow in 

 rich soil and in the dampness and protection from 

 cold afforded by the completed forest. Like most 

 of the tropical emigrants they have lived for count- 

 less generations in the Torrid Zone; they and 

 their ancestors have struggled for light, for food, 

 and for a place to live in denser forests than these 

 and where the battle for life never ceases a second 

 in the year. They have become fighters from 

 necessity; their forbears were warriors of cun- 

 ning and strength, and they have inherited the 

 instinct of aggressiveness. 



The young trees of these later migrants can 

 flourish in more crowded situations and where 

 there is less light than can the natives of the warm 

 temperate regions. The ground in a tropical 

 forest is an almost solid mass of roots which are 



