of the pool, to hunt minnow round the shallows; but their home by day
is the still deep; and their preference of the lasher pool to the
quiet water above is due merely to the greater abundance of food.
Chalk trout, then, are large not merely because the water is swift.

Whether trout have not a specific fondness for lime; whether water of
some dozen degrees of hardness is not necessary for their
development? are questions which may be fairly asked. Yet is not the
true reason this; that the soil on the banks of a chalk or limestone
stream is almost always rich--red loam, carrying an abundant
vegetation, and therefore an abundant crop of animal life, both in
and out of the water? The countless insects which haunt a rich hay
meadow, all know who have eyes to see; and if they will look into the
stream they will find that the water-world is even richer than the
air-world.

Every still spot in a chalk stream becomes so choked with weed as to
require moving at least thrice a year, to supply the mills with
water. Grass, milfoil, water crowfoot, hornwort, starwort,
horsetail, and a dozen other delicate plants, form one tangled
forest, denser than those of the Amazon, and more densely peopled
likewise.

To this list will soon be added our Transatlantic curse, Babingtonia
diabolica, alias Anacharis alsin astrum. It has already ascended the
Thames as high as Reading; and a few years more, owing to the present
aqua-vivarium mania, will see it filling every mill-head in England,
to the torment of all millers. Young ladies are assured that the
only plant for their vivariums is a sprig of anacharis, for which
they pay sixpence--the market value being that of a wasp, flea, or