FRESH-WATER AQUARIUM. 53 



it were, on its surface. I have received plants of it from 

 the mouth of the Fishkill Creek, where Dr. Torrcy informs 

 me it grows in such profusion, that he has frequently 

 found a difficulty in pushing a boat through its tangled 

 leaves. This plant is named in honor of an Italian natu- 

 ralist, by name Valisneri. It in appearance resembles a 

 grass, having long fronds, or leaves, starting from a deep- 

 set root in the soil at the bottom, and growing upwards 

 in the water towards the surface, often falling over in 

 graceful curves, forming "groves sequestered," through 

 which the fishes may roam. From the knowledge of its 

 natural mode of growth, we learn that it will flourish only 

 when well rooted in the sand and gravel at the bottom 

 of the tank ; indeed, I doubt not that it would grow 

 still better if we used a layer of soil placed beneath the 

 gravelly bottom of our Aquarium. This plant can be 

 easily distinguished on account of its resemblance to a 

 wide grass, as there is no other fresh-water plant like it 

 in form, the common sea-grass (.Zostera marina) being 

 somewhat like it in appearance ; but that grows only in 

 the sand of the sca-shorc. The VaHsneria is propagated 

 by off-shoots, which is a peculiar feature of the order lly- 

 drocharida, to which this plant belongs ; and Mr. Lloyd 

 mentions, that from six small roots he procured, during 

 one summer, no less than thirty-two healthy plants, all of 

 which blossomed freely. One of the female flower-stalks of 

 these plants he measured, and found it to be as much as 

 live feet in length. This is one of the plants in which 

 tlie circulation of the sap may be observed under the mi- 

 croscope. 



