OF THE VALJSNERIA. 255 



and sinking under water at night, and rising again in 

 the morning, are conformable to what every body has 

 observed in the Ngmpfattt" 



I have been the more particular in the above quota- 

 tions, because the veracity of Theophrastus has lately 

 been somewhat rudely impeached, on very question- 

 able authority. For my own part, I think what we 

 see of the Nymph&a in England is sufficient to render 

 the above account highly probable in a country where 

 the sun has so much more power, even if it did not 

 come from the most faithful and philosophical bota- 

 nist of antiquity, and I have always with confidence 

 cited it on his authority. The reader, however, will 

 perceive that the only important circumstance for our 

 purpose is the closing of the flowers at night, which is 

 sufficiently well established. 



"^ But the most memorable of aquatic plants is the 

 Valismria spiralis, well figured and described by 

 Micheli, JVor;. Gen. t. 10, which grows at the bottoms 

 of ditches in Italy. In this the fertile flowers stand on 

 long spiral stalks, and these by uncoiling elevate them 

 to the surface of the water, where the calyx expands 

 in the open air. In the mean while plenty of barren 

 flowers are produced on a distinct root, on short straight 

 stalks, from which they rise like little separate white 

 bubbles, suddenly expanding when they reach the 

 surface, and floating about in such abundance as to 

 cover it entirely. Thus their pollen is scattered over 

 the stigmas of the lirst-meiitioned blossoms, whose 



