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great increase of the mineral ingredients originally present. It follows 
then, as a natural deduction, from the successful demonstration of 
these premises, that the same balance should be capable of being 
established, under analogous circumstances, in sea water. Andina 
paper published in January, 1852,* I stated that I was, at that time, 
“attempting the same kind of arrangement with a confined portion of 
sea water, employing some of the green sea-weeds for the vegetable 
member of the circle, and the common periwinkle as the representa- 
tive of the water-snail.” 
The sea water with which the experiments I am about to detail 
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 animal life. And 
here opinions were at variance, for one naturalist friend whom I con- 
sulted, advised me to employ the Rhodosperms ; another stated that 
it was impossible to make the red weeds answer the purpose, as he 
had tried them, and strongly recommended the olive or brown- 
coloured Algz ; while, again, others thought that [ should be more 
successful with those which had in theory first suggested themselves 
to my own mind, namely the Chlorosperms. After. making numerous 
unsuccessful experiments with both the brown and the red varieties 
of Alge, | was fully convinced that, under ordinary circumstances, 
the green weeds were the best adapted for the purpose. 
This point having been practically ascertained, and some good 
pieces of the Enteromorpha and Ulva latissima in a healthy state, 
attached to nodules of flint or chalk, having been procured from the 
shore near Broadstairs, several living animal subjects were introduced 
together with the periwinkle. Everything progressed satisfactorily, 
and these all continued in a healthy and lively condition. 
My first trials were conducted in one of the small tanks which had 
been used for fresh water; but as it was necessary, during the unsuc- 
cessful experiments with the brown and red sea-weeds, to agitate and 
aérate the water, which had been rendered foul from the quantity of 
mucus or gelatinous matter generated during the decay of their fronds, 
until the whole had become oxidized, and the water rendered clear 
and fitted for another experiment, it was, therefore, for greater conve- 
nience, removed into a shallow earthen pan and covered with a large 
* ‘Gardeners’ Botanical Magazine and Garden Companion, Jan. 1852. 
