THE BOG. 161 



a river, the current of which is at all rapid, would 

 very soon be stripped of its foliage ; and, deprived 

 of this, the stem would not elongate, so that the 

 plant would never reach the surface of the water 

 to blossom. To obviate this difficulty apparently, 

 a wise Providence has ordered that, so long as the 

 stem remains under water, it shall bear no ex- 

 panded leaves, but a vast number of capillary fibres, 

 resembling the leaves of Fennel. These wave to 

 and fro in the water, and, offering little resistance, 

 are uninjured by the most violent floods. But 

 when the water has retired, and the extremity of 

 the stem reaches the surface, the plant seems 

 endowed with a new power ; the leaves, which it 

 now sends out, are no longer capillary, but dilated 

 and nearly round, eminently adapted for floating, 

 themselves, and for buoying up the still submersed 

 stem. Sometimes it grows at the bottom of rivers, 

 in places where a strong current runs all the year 

 round. In such situations it retains the same 

 characters throughout the whole of its existence ; 

 but that the tendency still exists to produce diffe- 

 rently shaped leaves under altered circumstances, 

 may be discovered by examining the banks of a 

 river which has had the soil taken from its bed 

 thrown on them. Here, if the bank be but mode- 

 rately damp, we shall in all probability find plants 

 sending out three-lobed leaves, and white flowers, 

 as if such a situation were the best adapted for 

 their perfect developement. Growing in a pond, 

 the water of which is still at all seasons, the sub- 

 mersed part of the stem produces capillary leaves, 

 although there is not in such cases so obvious a 

 reason for this peculiar formation. Water, whether 

 moving or stagnant, appears to excite in the plant 



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