HORN-WORT. 



93 



the water of the aquarium, many others might be 

 mentioned which could so be planted as to lend an 

 additional charm to the exhibition of living animal 



Fig. 43- 



Horn-wort (Ceratophyllum demersum). 



and vegetable forms. Among these we recommend 

 the sweet flag (Acorus calamus) and the bur reed 

 (Sparganium ramosuvi) as being not only the most 

 easily procurable, but as forming the most graceful 

 adjuncts. They may easily be planted within the 



