Mr. R. Warington on Marine Vivaria. 319 XXX.-^U/i Pmemny the Balance between the Animal and Ve-aetable Organisms in Sea Water. By Robert Warington.* In the published notices of my experiments of 1849, to maintain the balance between the animal and vegetable organisms in a confined and limited portion of water, the fact was demonstrated, that, in consequence of the natural decay of the vegetation, its subsequent decomposition and the mucus-growth to which it gave rise, this balance could only be sustained for a very short period, but, if another member were introduced, which would feed upon the decaying vegetation and thus prevent the accumu-lation of these destructive products — a function most admirably performed by the various species of water-snail — such balance was capable of being continuously maintained without the slightest difficulty ; and I may add, that the experimental proof of this has now been carried on, in a small tank in the heart of London, for the last four years and a half, without any change or disturbance of the water ^ the loss which takes place by eva-poration being made up with rain or distilled water, so as to avoid any great increase of the mineral ingredients originally present. It follows then, as a natural deduction, from the suc-cessful demonstration of these premises, that the same balance should be capable of being established, under analogous circum-stances, in sea water. And in a paper published in January l853t, I stated that I was, at that time, "attempting the same kind of arrangement with a confined portion of sea water, em-ploying some of the green sea-weeds for the vegetable member of the circle, and the common periwinkle as the representative of the water-snail." The sea water with which the exjieriments I am about to de-tail were conducted, was obtained through the medium of one of the oyster-boats at the Billingsgate fish-market, and was taken from the middle of the English Channel, My first object was to ascertain the kind of sea-weed best fitted,, under ordinary circumstances, for keeping the water clear and sweet, and in a sufficiently oxygenated state to sustain ani-mal life. And here opinions were at variance, for one naturalist friend whom I consulted, advised me to employ the Ilhodosperms ; another stated that it was impossible to make the red weeds answer the purpose, as he had tried them, and strongly recom-mended the olive or brown-coloured Algae ; while, again, others thought that I should be more successful with those which had * Communicated by the Author, having been read at the Hull Meeting of the British Association. t Gardeners' Botanical Magazine and Garden Companion, Jan. 1852,
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