SEA- WATER AQUARIA. 119 



Put the same water within the confined limits of an aquarium, 

 and the case is quite altered. There is no growing vegetation 

 present, neither is there the unceasing movement of Nature, 

 — nothing of any importance, in fact, to counteract and destroy the 

 impurity of the water. Allow the water to remain in the aquarium 

 without changing it, or, in other words, without introducing more 

 impurities by the addition of fresh water, and affairs will right 

 themselves naturally. Air is absorbed by the water surface in 

 contact with the atmosphere, and vegetation of a low form grows 

 from invisible germs existing in the water, with the result that the 

 impurities at first present are gradually destroyed, and the water 

 slowly becomes clear, pure, and fit to sustain animal life. 



The late W. A. Lloyd, as far back as 1874, wrote very empha- 

 tically on these matters. He said, in an article in the Popular 

 Recreator : — "I have incidentally mentioned failures from the use 

 of new sea-7vate?% and I have known many persons to have lost 

 (from this cause, without knowing it) animals at the seaside which 

 they would not have lost inland. It is so always when there is an 

 occasional renewal of water from the sea wherever the water is 

 turbid, and the ill result is increased in proportion to the fre- 

 quency of renewal. It is to this source that may be traced the 

 too-small commensurate biological value of all public seaside 

 aquaria built up till now, when their very large money-cost for 

 erection and maintenance is remembered. That is to say, too 

 much reliance has been by the constructors placed on the facilities 

 which the position of such aquaria give for obtaining new sea- 

 water, and that sea-water is almost always impure, and of much 

 varying density at the shore. Animals may or may not live in 

 such shore-water in the sea ; but it is a very different thing to 

 living in the same water in the confined limits and measurelessly 

 smaller aeration of an aquarium, whence, unlike as in the sea, 

 they cannot escape if they find the water and other circumstances 

 unfit for them. 



The advantages of having a marine aquarium at the seaside 

 consist in the ease with which some animals can be obtained 

 without their being carried during a long and exhaustive journey, 

 and in the saving of some of the cost of the first supply of sea- 

 water. But, once obtained, thaifrst supply should be the iast^ and 



