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annuals. Wlieie perennials have obtained a foothold, the long, thick tap- 

 root is usually suillcient to give a new lease of life. Against the mechanical 

 effects of the sand, the prostrate habit, the dissected leaves and at times 



Any victory of the plants is but apparent. After years 

 of possession of the soil they may be dislodged by the shift- 

 ing: of the soil under the action of the wind. 



an extremely tough and resistant structure. 1 he first two are by far the 

 more common and apparently the more effective. 



From the standpoint of the plant no situation can be more pitilessly 

 cruel than the stretches of white, restlessly shifting sand making up the 

 beaches and dunes. In a certain sense, no other situation furnishes ecologi- 



