392 IN LOWER FLORIDA WILDS 



one. If such depredations were to continue un- 

 abated through a long series of years they might 

 entirely prevent the plants from propagating and 

 they would eventually be exterminated throughout 

 the area in which they were attacked. In this 

 way we might account for the absence of certain 

 trees and plants in regions where we would 

 natvirally expect to find them. 



A cold winter or a series of them undoubtedly 

 destroys great niunbers of injurious insects and 

 fungi and may check diseases which prey on our 

 plants. Such a winter or winters are followed by 

 an unusually vigorous growth of vegetation, since 

 it has fewer enemies to cope with. This luxuriance 

 of growth and scarcity of enemies gives the sur- 

 vivors an excellent opportunity with a greater 

 share of food and room, and as a consequence the 

 destroyers again wax lusty, multiply with great 

 rapidity, and in a short time the equilibrium of 

 nature is reestablished and the old order of life is 

 restored. 



There are those who believe there is imminent 

 danger that many of our cultivated plants will 

 become exterminated by imported diseases and 

 injurious insects and that unless the strictest in- 



