264 
POPULAR SCIENCE REVIEW. 
1 . 
2 . 
3. 
4. 
5. 
6 . 
7. 
9. 
10 . 
11 . 
12 . 
Sandhoppers ( Talitrus ), in pounds weight 
Shrimps ( Crangon ), in quarts * 
Crabs ( [Carcinus ) f in gallons * 
„ {Cancer), large I „ numbers . 
Scallops {Pecten) large, in numbers 
Oysters ( Ostrea ) „ „ 
Cockles ( Cardium ), in gallons 
Mussels {Mytilus) „ . 
Whelks (Buccmum) {'" numbers 
Fish, chiefly Whiting {Gadus), in pounds weight 
Smelts’ roe {Osmerus) „ „ 
Green seaweed {JJlva), purchased 
12 
4735 
137 
1450 
32 
2195 
18 
3544 
7 
100 
3159 
14 
400 
{Conferva), grown in tanks, quantity unknown, 
And, in addition, we obtain occasional and unrecorded sup- 
plies from neighbouring fishmongers when the regular supply 
runs short. Of this animal food, all but the denominations 
9 and 10 are kept alive in a series of reserve tanks till the 
moment of being eaten. Scarcely any uneaten food, and never 
any excrement, is manually removed ; but all which is not 
consumed by the animals is chemically dissipated, without 
filtering, by the enormous volumes of air constantly being in- 
jected into every tank by Leete Edwards and Norman’s 
machinery, • the speed of which is accelerated (i.e. the oxy- 
genation is quickened) when the water is slightly turbid from 
an excess of organic matter. All this I have explained more at 
length in the w Official Handbook to the Crystal Palace 
Aquarium,” and in u Observations on Public Aquaria,” both 
published at the Crystal Palace. It is this power of oxy- 
genating, or consuming, or burning, at a low temperature, 
termed by Baron Liebig “ eremacausis,” * which expresses the 
real work done in an aquarium, and the force necessary to do that 
work. Even our thick beds of sand and shingle at the bottoms 
of each tank are so fully charged with air, that one thrust of a .8 
stick will release a pint of it in bubbles. This is a source of 
purification and health quite unknown till recently. Conse- 
quently the floors of our tanks (excepting the sea anemone 
tanks) are as speckless and as free from the blackness caused by 
sulphuretted and carburetted hydrogen gas, as on the day they 
were laid down in 1870. If we have an -excessive growth of sea- 
weeds anywhere, we turn in a shoal of grey mullet ( Mugil 
cajpito\ who nibble it down close, like sheep in a field of grass. 
This leads me to say that at present we do not know how to 
grow the higher marine algse, the red, the brown, or even the 
* From the Greek “to remove by burning, or by fire.” The words 
u caustic ” and u cautery ” have the same derivation. 
