376 THE FRESH-WATER AQUARIUM. 
Besides these plants the floating Duckweed (Lemna tri- 
sulca) is a very valuable addition to the collection. Water- 
lily plants are not only difficult to make grow, but their 
leaves are apt to be ill-proportioned to the size of the tank. 
In duckweed both these troubles are done away with, for we 
have a plant which is easily grown, and one which gives to 
the aquarium the appearance of a miniature pond. It is 
found in brooks at the roadside and in shallow ponds, espec- 
ially in the autumn season. The Limnocharis Humboldtii, a 
lily sometimes grown in tanks in greenhouses, is also a good 
plant for the aquarium, where, if care be taken, it will blos- 
som freely. There is a moss-like plant of bluish green 
color, found growing on stones in brooks, and under bridges 
in shady places in the water. It is called Fontinalis antipy- 
retica, and it is one of the few brook plants that will do well 
in the aquarium. The water buttercup, Ranunculus aquati- 
lis, has only its beauty to recommend it, for it hardly sur- 
vives the winter in the tank. A plant of the Frog’s-bit 
family, Anacharis Canadensis, is another excellent one for 
the aquarium. It gives to the fresh-water aquarium an ap- 
pearance similar to that which the Ulva latissima gives to 
the marine tank. 
Having made a collection of plants, ied thoroughly 
washed them, the next thing is to arrange them in the 
tank. This arrangement must be according to the taste of 
the collector. One way, perhaps as good as any, is to make 
four bunches of plants of suitable size, and place one in each 
corner of the tank if it is rectangular; they do not then ob- 
Vine 

dere TE d. anag ue nr 

wering; 01 r rooting in 
the seam sometimes with few or no leaves òr bladders (name tebe Dii, a little 
= _* Polamogeton. ,Pond-weed. Flowers perfect. Sepals 4, rounded, valvate in the bud. 
pais; y sessile, 2-celled. Ovaries 4 (rarely only 

j one), with. an asce ascending campylotropous ovule. Stigma sessile, or on a short style. 


