9^ 



Types of Agnatic Environment 



of the water in floating rafts, which steadily extend into 

 deeper water. The pond in the center of Montezuma 

 Marsh shown in the preceding figure is completely 

 surrounded by a rapidly advancing, half-floating even- 

 fronted phalanx of cat-tail. 





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Fi<;. 27. ''The Cove" at the Cornell University Biological Field Station, in 

 time of high water. Early summer. Two of the University buildings 

 appear on the hill in the distance. 



Later conditions in such a marsh are those illustrated 

 by our frontispiece : regularly alternating spring floods, 

 summer luxuriance, autumn burning and winter freez- 

 ing. This goes on long after the work of the cat-tail, 

 the pioneer landbuilding, has been accomplished. 

 The excellent aquatic collecting ground shown in the 

 accompanying figure is kept open only by the annual 

 removal of the encroaching flag. 



