34 THE AQUAVIVARIUM. 



I have grown the Aponogeton distacliyum, an 

 aquatic plant from the Cape, which has pretty 

 sweet-scented flowers, and which it keeps pro- 

 ducing all the year round. This plant grows in 

 great perfection in the open air, in the pond at 

 the Botanic Gardens, Edinburgh, and is also 

 growing in the fresh- water tanks in the Zoolo- 

 gical Gardens, Regent's Park, London. The 

 Pistias, Trapas, and Pontederias, are all foreign 

 plants, species of which are to be seen in our 

 hothouses, arid some might be tempted to grow 

 in a domestic Aquavivarium. 



III. ACEOGENS, OE FLOWEELESS 

 PLANTS. 



There are two families of this class of plants, 

 which are entirely aquatic, and from which the 

 Aquavivarium may with advantage be supplied. 

 These families are the Charas, or Stoneworts (Cha- 

 racece), and Sea- weeds (Algce). 



THE CHARACE^E are represented in Great Britain 

 by two genera, Nitella and Chara. All the 

 species are easily known in the water by con- 

 sisting of a central branch, which is composed 

 of elongated cellular tubes, and at the junction 

 of each tube with the other it gives off a series of 

 branches, which surround the primary tube in 

 the form of a whorl. In. the axils formed by the 

 branches with the primary stem, the parts which 

 represent the stamens and pistils of the flowering 

 plants are seated. These parts are of two kinds, 

 and are called " nucules " and " globules." The 

 nucules are green, and represent the pistil, whilst 

 the globules are of an orange-colour, and repre- 

 sent the stamens. The globules contain cells, in 

 which are contained small moving, worm-like 



