THE AQUARIUM 79 



where the weed will be permanently submerged, and build up 

 other pieces into a loose rockery. The shore crab, and even 

 some of the shore fishes, prefer to spend part of their time out 

 of water, and are more tolerant of moist air than of foul water. 

 The aquarium, further, should not be filled up to the brim, so 

 that limpets and similar forms can crawl up out of the reach of 

 the water, in order to imitate for themselves the ebb and flow of the 

 tide. It need hardly be repeated that all stones placed in the 

 tank should be thoroughly washed in seawater before being 

 introduced. When the stones and gravel have been arranged, 

 pour in the water gently as before, and leave it to settle. If it 

 does not become perfectly clear, it must be thrown out and the 

 washing process recommenced, for the majority of shore animals 

 are very intolerant of muddy water. 



If the aquarium is to be established at some distance from 

 the sea, the difficulties are considerably greater, for the tempta- 

 tion is great to crowd the animals during the journey, and they 

 will probably die during transit, or never completely recover. 

 Success is only possible if the animals are placed, in very small 

 numbers, in large jars of clean water the big bottles used by 

 confectioners for storing sweetmeats do well, and can be bought 

 for a few pence each. In addition a considerable store of clean 

 water should be taken, and as soon after arrival as possible the 

 animals should be removed from their travelling jars, and placed 

 in flat pans with clean water, till their permanent home is ready. 

 In these vessels, as indeed in the aquarium tank, a mark should 

 be made on the side to indicate the height of the water when 

 first poured in. It evaporates with some rapidity in a warm 

 room, and as this means increasing concentration of salt, river 

 water should be periodically added to preserve the original density. 

 Seaweeds, sea-anemones, some of the crustaceans, the molluscs 

 and the Echinoderms are sometimes better sent in closed cases 

 without sea water. The weeds, together with the stones to which 

 they are attached, should simply be packed with refuse weed so 

 that they will not jostle, while the animals should be wrapped 

 in fresh wet weed, and placed loosely in a jar, taking care so to 

 pack them as to prevent damage against the walls of the jar 

 or case in transit. 



