THE MAEINE AQUARIUM 61 



In the first place, let us advise the amateur to confine his atten- 

 tion to the smaller species of weeds that are commonly found in 

 small and shallow rock pools, for the successful growth of the larger 

 purple and olive weeds will probably be beyond his power, even 

 though his tank be one of considerable capacity. The best plan is 

 that we have already suggested namely, to chip off small pieces of 

 rock with tufts of weed attached, and to fix them amongst the 

 rockery of the aquarium, being careful to place those that grew in 

 shallow water with full exposure to the light, and those which 

 occupied sheltered and shady places in the rock pool, respectively, 

 in similar situations in the artificial pool. 



For the purposes of aeration we have to rely principally on the 

 bright green weeds, and preference should be given to any of these 

 that exhibit, in their natural habitat, a multitude of minute air- 

 bubbles on the surface of their fronds, for the bubbles consist princi- 

 pally of oxygen that is being liberated by the plant, and denote 

 that the species in question are those that are most valuable for 

 maintaining the desired condition of the water in an aquarium. 



Any small sea-weed may be tried at first, but experience will 

 soon show that some are much more easily kept alive than others. 

 In this experimental stage, however, a constant watch should be 

 maintained for the purpose of detecting signs of decay in the 

 marine garden. A plant should always be removed as soon as it 

 presents any change from the natural colour, or exhibits the smallest 

 amount of slimy growths on the surface, for decomposing plants, as 

 well as decaying animals, will soon convert an aquarium into a 

 vessel of putrid and poisonous water. 



It seems almost unnecessary to name a selection of sea-weeds 

 for small aquaria, seeing that our rock pools produce so many 

 extremely beautiful species, most of which may be successfully kept 

 alive in a well-managed tank; but the common Sea Grass (Entero- 

 morpha compressd), and the Sea Lettuce (Ulva latissima), also 

 known locally as the Green Laver or Sloke, are particularly useful 

 for the aeration of the water ; while the Common Coralline (Coral- 

 Una officinalis), the Dulse (Schizymenia edulis), the Peacock's tail 

 (Padinapavonia), the Irish or Carrageen M.oss(Chortdruscrispus), 

 Callithamnion, Griffi thsia setacea, Plocamium plumosium, Rhody- 

 menia palmata, Rliodophyllis bifida, and Ceramium rubrum are 

 all beautiful plants that ought to give no trouble to the aquarium- 

 keeper. 



It is not advisable to introduce animal life into the aquarium 



