n in the agreement. At present there are agreements for
thirty-three tables, and since the foundation of the station nearly 1200
biologists have worked there. The current expenses are paid out of the
table-rents, the entrance fees to the public aquarium, and an annual
subvention paid by the German empire."

In England a station on similar lines, but on a smaller scale, is
maintained at Plymouth by the Marine Biological Association of the
United Kingdom, with the help of subsidies from the government and the
Fishmongers' Company.

Little difficulty is experienced in maintaining, breeding and rearing
fresh-water animals in captivity, but for many various reasons it is
only by unremitting attention and foresight that most marine animals can
be kept even alive in aquaria, and very few indeed can be maintained in
a condition healthy enough to breed. Much experience, however, has been
gained of late years at considerable expense, both in England and
abroad. In starting a marine aquarium of whatever size, it should be
obvious that the first consideration must be a supply of the purest
possible water, as free as may be, not only from land-drainage and
sewage, but also from such suspended matters as chalk, fine sand or mud.
This is most ideally and economically secured by placing the station a
few feet above high-water mark, in as sheltered a position as possible,
on a rocky coast, pumping from the sea to a large reservoir above the
station, and allowing the water to circulate gently thence through the
tanks by gravity (Banyuls). At an inland aquarium (Berlin, Hamburg),
given pure water in the first instance, excellent if less complete
results may nevertheless, be obtained. The next consideration is the
method by which oxygen is to be supplied to the organisms in the
aquarium. Of the two methods hitherto in use, that of pumping a jet of
air into tanks otherwise stagnant or nearly so (Brighton), while
supplying sufficient oxygen, has so many other disadvantages, that it
has not been employed regularly in any of the more modern aquaria. It
is, however, still useful in aerating quite small bodies of water in
which hardy and minute organisms can be isolated and kept under control.
In the other method, now in general use, a fine jet of water under
pressure falls on to the surface of the tank; this carries down with it
a more than sufficient air-supply, analysis showing in some cases a
higher percentage of oxygen in aquarium water th