618 Aquaria: Their Past, Present, and Future. [ October, 
their side. In reply, the society answered that a circulatory 
system did exist in a part of the sea-water series, but that it was 
almost useless; and I then pointed out that that was because 
the reservoir into which the sea-water entered after it had run 
through the show-tanks was too small in relation to the dimen- 
sions of the latter, and that the reservoir should be several times 
greater than the show-tanks. My reasoning was all in vain, 
however, for the society went on throwing away the sea-water 
when it was only temporarily unfitted for use, and getting at a — 
cost of several hundreds of pounds yearly a weekly supply from 
the sea, especially when soon afterwards another evil made its 
appearance, consisting of a greenish-brown dense opacity, per- 
meating the water and quite hiding from view all it contained. 
This was caused by excess of light, for I found that darkness 
removed it and made the water clear again; and this led to Mr. 
E. Edward’s invention of the dark-chambered tank, a modifica- 
tion of which is now, or should be, employed in all public 
aquaria where adequate results are aimed at and attained. So, 
at this early period, 1853-62, though in theory the Zodlogical 
Society of London, and every one else who maintained aquaria, 
used the same unchanged water, especially sea-water, yet most 
persons sent to the sea, or to dealers, of which I was then one, 
for occasional new supplies. However, from 1853 to 1859, when 
I could not possibly get new sea-water for my little jars, I 
merely increased the quantity of water to about eight or ten 
times as much as those jars cdllectively held. Thus the aggre 
gate contents of my jars were about six or eight pints ; and in à 
now historical earthenware foot-pan, kept dark in a cool corner 
at hand, I had five or six gallons more water, containing neither 
animals nor plants, and when aught occurred to disturb the equ 
librium of life in these jars, either from excess of light or heat 
by standing on a light window-sill, or from excess of food, oF 
from there being too many animals in a small space, instead of 
throwing away the water thus temporarily rendered unfit to sus 
tain life, I merely restored it to a right condition by poutms the 
contents of these jars into the foot-pan, which was 80 large be 
relation to the dimension of the jars that I could immediately 
dip them up full from it (the foot-pan) without the water being 
perceptibly the worse for it, especially when I so contrived mat- 
ters that these transfers were made, not in one day, but on wish 
cessive days. Thus, in London, far from the sea, which I h 
never seen, I was so far, aquarially speaking, as well off as 
