THE AQUARIUM. 245 



kept, it is necessary that some beings should be introduced for the pur- 

 pose of feeding on the decaying vegetable matter. This desideratum 

 is supplied by the various forms of phytophagous mollusca. So that, 

 to maintain perfect health, it is necessary to place in the glass sea- 

 weeds, mollusca, fish, &c. ; but those should not be put together which 

 will devour each other. The sea-water should be kept near the same 

 temperature always, about 60 Far. ; and the loss by evaporation 

 supplied by adding rain or distilled-water from time to time. All 

 dead animal or vegetable matter should be removed, and the glass vase 

 kept near the window, exposed to the influence of light. 



It is quite possible to make an artificial sea-water, for the purpose 

 of supplying these tanks. In water manufactured as follows, the ani- 

 mals and plants will thrive and do well. Take 15 pints of water from 

 the house- cistern, and add to it 7 ozs. of table-salt, \ oz. of Epsom 

 salts, 80 grains of chloride of potass, and 400 grains of chloride of mag- 

 nesia. Any chemist can supply or prepare this. 



Mr. N. B. Ward, whose fern-cases have now become universal 

 favourites, made the earliest attempt to establish, on a small scale, an 

 " aquarium for fish and plants." He writes :* "I placed ten or twelve 

 gold and silver fish, in company with several aquatic plants, viz. 

 Villisneria spiralis, Anacharis alsinastrwn, Pontederia crassipes, Pa- 

 pyrus elegans, and Pistia Stratiotes, which plants, by means of their 

 vital actions, as had long been well-known, maintained the purity of 

 the water, and, as in the atmosphere, kept up the balance between 

 the animal and vegetable respirations. Placed in the centre of my 

 fern-house, and nearly surrounded by rock-work (rising five or six 

 feet above the margin of the vessel), clothed with Adiantum and 

 other lovely ferns, and partially overshadowed with the palmate leaves 

 of Corypha australis, the plants and fish continued to flourish for 

 years, The only enemy I had to contend with was a species of Vau- 

 cJieria, which from its rapid growth, required to be kept constantly 

 in check. My friend, Mr. Bowerbank, always alive to scientific in- 

 quiries, followed up these experiments with equal success ; but sub- 

 stituted sticklebacks and minnows for the gold fish, and a few snails 

 (Limeus stagnalis) to get rid of the decaying leaves of Vallisneria 

 spiralis, &c." 



* "On the Growth of Plants in closely-glazed cases," by N. B. Ward, Esq., 

 F.R.S. 



