302 



ECO LOG Y. 



partially or completely destroyed, a new set of conditions is 

 presented over these areas. One of the most important is that 

 light is admitted where before towering trees permitted but a 

 limited and characteristic undergrowth to remain. Hundreds 

 of forms, which for years have been dormant, are now awakened 

 .from their long sleep, and new and recent importations of seeds, 

 which are constantly rushing in, spring into existence to fill the 

 gap, multiply their numbers, and make more sure the perpetua- 

 tion of their kind. 



469. The weaker ones are overcome. The earliest to appear 

 are not always the ones to endure the longest, and a battle 



Fig. 253- 



Abandoned field in Alabama, growing up to broom-sedge and trees. (Photograph by 

 Prof. P. H. Mell.) 



royal takes place during years for supremacy. The weaker 

 ones are gradually overcome by the more vigorous, and a new 

 crop of trees, which often springs up in such places, finally 

 usurps again the domain, in the name of the same or of a 

 different species. 



470. Feral plants in neglected fields. Domestic plants pro- 



