THE MARINE AQUARIUM. 5g 
understood that where real sea water can be easily obtained, 
as at spots near the coast, it is undoubtedly the best, 
though, in some respects, the artificial preparation is pre- 
ferable, because less liable to certain eccentric changes of 
constitution, which will fall under our attention further on. 
Sea-water contains the spores of plants, and the germs 
of many forms of animal life which may have develop- 
ment in the tank, and when these births occur, it is a 
special gratification to the possessor. But such germs 
may also decay, and cause putrescence; and if a tank is 
neglected, the water is liable to get cloudy, the stones 
black, the sides of the vessel semi-opaque, and the 
animals diseased. Death soon sets his black seal on the 
undertaking when such a state of things occurs, and the 
collection, however costly or well formed at first, may be 
lost. Now such misfortunes as these are preventible, as 
it will be my duty to show presently, but I here call atten- 
tion to the fact, that artificial sea-water is much less liable 
to get out of condition from the very absence of organic 
matter, which on first reflections, we should regard as 
a disadvantage. Thus, the prepared material has certain 
advantages over the natural; we lose the chance of rear- 
ing new additions to the stock through the introduction 
of minute organic germs; but incur no danger of those 
same germs perishing and polluting the bright lymph. 
But artificial water is quite unsuited for animal life of 
any kind, until it has been brought into condition by 
} means of growing weeds for eight or ten days, and for 
crustacea, star fishes, and fishes proper, it is not suitable 
till it has been in use for many months, and even then 
