CHAPTER XVIII 

 The Survival of the Fittest 



THE very fact that tropical life exists at 

 all in Lower Florida is in itself a proof of 

 the survival of the fittest. It all had to 

 cross the ocean and on its arrival estab- 

 lish itself despite the competition of forms which 

 already occupied the region. In addition to this 

 the environment in Florida is not so congenial as 

 in the regions from which this life migrated. The 

 lower part of our State has a colder climate than 

 any part of the American tropics which lies near 

 the level of the sea; food is not so abundant and 

 our soil is generally poorer. Land birds of weak 

 flight, reptiles and batrachians of degenerate type, 

 or mammals and insects of uneconomic habit would 

 be almost entirely shut out. The seeds of a great 

 number of plants sink in salt water, and some 

 that float lose their vitality in the sea. Only the 

 strong and fit, those with great vitality, could ever 



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