EIGHTH ANNUAL MEETING. 47 
is furnished anew is clear at times, and at otherscloudy. I may 
as well here explain that sea-water, no matter how clear it may 
be when procured, will become so clouded within a week that a 
person cannot see in it to the extent of a foot. This is caused 
by the organic matter which, if the water is circulated, will, in 
time become burned up and deposited upon the bottom of the 
reservoirs in the form of*harmless sediment, say in from one to 
three months, or even longer, before the water becomes beauti- 
fully limpid and of the highest transparency. It is after this 
purification that plants begin to grow and beautify the hard 
lines of the rock-work ; and in my opinion, the water in a ma- 
rine aquarium should be circulated for six months in a dim twi- 
light before a fish is placed in it. One of the worst things to 
contend*with in a public aquarium is the light, which, however 
necessary for the people who visit it, is very detrimental to the 
fishes. 
In speaking of aquarium-keeping, I will say that I would 
not include in this term any system in which the entire stock 
required renewing every three months, as there are many fishes 
which are quite well adapted to aquarium life, and who will 
thrive there if the tanks are properly kept. 
Although aeration by circulation is the proper and only 
correct method for public acquaria, the aid of vegetation is 
not to be despised, and marine vegetation is somewhat difficult 
to grow ; yet if the rock-work is so arranged as to give light 
and shade, and even gloom, in places, the plants which would 
thrive will appear of themselves, their spores being everywhere 
in sea-water. The green alge (Chlorosperma) will come in the 
lighter parts, while in the obscure places those most delicate 
 “red-weeds” (Rhodosperma) may grow. If, however, it is thought 
best to introduce these plants it will be found that most of them 
will die, as before they get fairly settled in their new home the 
stimulus of the light will have covered them with green or 
purple filamentous weeds, as conferva, oscillatoria, etc., which 
conceal them with their abundant growth, and finally smother 
them. The mullets (family mugzde) are the only good vegetable- 
eaters among our marine fishes which thrive in aquaria, and 
with the vegetable-eating mollusks, which may be carefully in- 
