apparently fatal to its parasites. The sea-lice,
still adhering to the buck of gpfitt, glittering
salmon, are sure proof that it is a fresh-run
fish—a new arrival from the ocean. They
quit their hold an hour or two after entering
the river. On its return to the sea, the poor
shotten, emaciated salmon is suffering from a
worse nuisance, namely, whitish worm-like
iufestors of its gills, whose acquaintance it
has somehow made during its sojourn amidst
inland waters, but which are supposed to be
obliged to quit their hold soon after they
have heard the roar of the breakers and
tasted their quality.

The undecided and hypothetical way in
which these parasites of the salmon are
spoken of, arises from the fact that the
metamorphoses, and all the physical arrangements,
of such creatures are so extraordinary, and
the adaptation of living beings to the
circumstances under which they are required to
live, are so marvellous and unexpected, that
though the sea-louse and the fresh-water worm
(one found upon the scales of the fish, the
other on its gills) are believed to be utterly
distinct creatures, it is quite possible that
they are only successive forms of the same
individual parasite.

The sea-louse may be destined to
reproduce its kind in fresh waters, as well as
the salmon. Its minute young, in the shape
of animalcules, may be inviaioly dispersed
through the streams breathed by the fish, and
so may attach themselves to their ordained
habitat, the gills, during the passage of the
water through them. A transformation there,
while the salmon is living in his marine
quarters, and a shifting of place from the
internal to the outer cuticle, is less difficult
to imagine than the change of a bot, which
has lived for weeks in a horse's stomach, to a
winged fly, which shall buzz about the
quadruped and lay its eggs on the hide, only
within reach of the tongue that is to lick
them off and swallow them for hatching!
These mysteries are yet but imperfectly
unveiled.

A scale graduated in degrees of saltness, or
haliometer, might be drawn up, of which
fresh water would be the zero, and oceanic
saltness indicate a conspicuous stage—a sort
of a boiling-point—continuing on to higher
proportions of saline solution, until saturation
was attained; and it would be interesting to
note the range along the scale taken by
different creatures as their own especial element.
Plaice and flounders are capable of bearing
water perfectly fresh; several of the flat fish
will put up with a very short allowance of
salt in their respiratory and natatory medium;
soles and turbots, for instance. Indeed, no
fish ought to enter the mouths of rivers which
cannot cheerfully submit to such a deficiency;
though worse misfortunes are in store for
them. Some workman repairing the quay-
head at Great Yarmouth, observed a fine
turbot swimming along by the water's edge,
and inspecting their progress. They quietly
got between him and the deep water, and
hoisted him out with their hands upon the
quay itself. The scribe saw him while still
living and repenting his folly, and had the
pleasure of dining off him next day. While
that delicious daughter of the sands, the
cockle, seems to like best to keep out to sea,
oysters fatten all the faster for being subject
to a slight influence of waters from the land.
At Stiffkey, in Norfolk, celebrated for mussels,
the best are the sluice mussels. The
brown shrimp runs into brackish waters, an
example which is not followed by the red
shrimp or the prawn. These are marine
things, therefore, enjoying, for a time at least,
a degree of saltness below ocean-point. Above
it are the creatures that swim unhurt in that
distasteful mixture, the Dead Sea, or, still
more surprising, in Mr. Darwin's South
American brine-ponds.

It does not appear very clear, how it is that
most of the fish inhabiting fresh-water lakes
are killed by the irruption of a certain number
of gallons from the sea. Salt does not
combine with living bodies. You may take
ever so many dips at Brighton without being
converted into pickled young gentlemen.
There is nothing structural visible to the eye,
why salt water should be fatal to one fish
and indispensable to another; any more than
there is, among plants, why a night's frost,
which leaves one species untouched, should
burn, or dissolve another. Comparative
anatomy in vain looks for the physiological
reason why the cray-fish and the fresh-water
mussel should be confined to ponds and
streams, while the edible mussel and the
lobster, so closely resembling them, can live
only in saline water. The sea-worm which
our fishermen dig from the sands at ebb tide,
for bait, is certainly larger, but looks as
tender-skinned as its first cousin, the common
earth-worm, to which a few drops from the
sea are an immediate sentence of death.
Many marine worms are more fragile and
thin-skinned than the medicinal leech, on
which the severe effects of salt are so familiar.
How delicate is the cuticle of the expanded
sea-anemone! Marine infusoria, in a living
state, appear to the eye just as etherial in
structure as their brethren from the softest
rain-water tank; and yet, bring the latter
into contact with the smallest bead or
droplet of salt water, and you will see what
happens.

To carry out properly his scheme both of
practice and study, Monsieur Coste requires
to have placed at his disposal a small government
screw-steamer drawing but little water,
and yet capable of going at a rapid rate. His
object is to be able to travel, at his discretion,
during the spawning season, from the northern
regions to the tropics, in short to all the
theatres of these grand phenomena of reproduction,
wherein Science promises to Industry
the most valuable revelations.