LOW LIFE.
Some persons go to the seaside every year for several weeks, and
yet know little of its treasures. Take away the bands, the bathing
machines, the itinerant entertainers of various kinds, the bustling
crowds that pass and repass on the grand parade, and they are lonely,
miserable, with nothing to occupy their minds. Of the illimitable sea,
the cliffs, the sands, the passing sails they soon tire. For a very
small sum, as money is considered to-day, such a person could acquire
a tolerable microscope, and a very little application to books would
put him in the way of getting an absolutely endless fund of interest,
knowledge, even amusement from it. Through the magic glasses he enters
another world; or, rather they enable him to see that other half of
Creation with which he has been rubbing shoulders all his life, yet
without seeing the creatures. With such an instrument and the knowledge
how to use it, a man may defy the demon _ennui_ wherever he may be.
With such an instrument at home a person who is not a naturalist may
be induced to look into a rock-pool, to take samples of its fauna
and flora, and by and by to become a naturalist without intending or
knowing it.
Behold how easy a thing it is! He has but to take away a phial full
of the water, a tiny bunch of coralline, the finer green weed, or a
snippet of sponge from the walls of the pool, and he has abundance of
material whose marvellous beauties of form and colour will delight and
astonish him when he has had time to examine it under the microscope.
For the coralline tuft and the lowly weed, when washed out in the
sea-water, will yield him multitudes of Infusoria, Rhizopoda, and the
infantile stages of many of the higher groups of life.
The Foraminifera are the minute creatures which have so largely
contributed to the formation of the enormous beds of chalk we find in
Surrey, Kent, Sussex, and other counties, such as the explorations of
the _Challenger_ showed us are being formed in the deep sea at the
present time. So minute are they that one hundred and fifty of them
placed side by side would not measure more than one inch, and of such
insignificant creatures the chalk is almost entirely composed. What
are they? How are they fashioned? How do they live? These questions
probably occur to the reader, and I must do my best to briefly answer
them.
There is a minute creature, plentiful in ditches and similar
accumulations of stagnant water into which decaying vegetation
has fallen. It is a minute speck of animated jelly, without form,
substance, or limbs. There is, in fact, no closer analogy than the
speck of almost clear jelly, to which in some mysterious way life has
been given. In the words of the late Dr. W. B. Carpenter, who made a
special study of these creatures: “A little particle of homogeneous
jelly[1] arranging itself into a greater variety of forms than the
fabled Proteus, laying hold of its food without members, swallowing
it without a mouth, digesting it without a stomach, appropriating its
nutritious material without absorbent vessels or a circulating system,
moving from place to place without muscles, feeling without nerves,
propagating itself without genital apparatus, and not only this, but in
many instances forming shelly coverings for symmetry and complexity not
surpassed by those of any testaceous animal.”
[1] It is now known that this jelly-like material is not of so simple
a character as was supposed a few years since: the most modern
microscopes prove it to be not devoid of structure.
With the exception of the last three-and-twenty words the above
description refers to the _Amæba_ and its allies; but in the
Foraminifera we have a sort of advanced type of amæbæ, a more æsthetic
race that have taken to build themselves houses, in most cases of
graceful form, such as are referred to in Dr. Carpenter’s concluding
words. One of the fresh-water amæbæ is named _Difflugia_, and it
distinguishes itself by coating the greater part of its small body
with particles of sand and other matter picked up as the _Difflugia_
rolls along. The Foraminifera do not resort to so clumsy a method
of satisfying their architectural instincts. In the course of their
feeding they take into their primitive systems a good deal of carbonate
of lime, and instead of casting this out as innutritious, useless
stuff, they secrete it as shell, in many cases not unlike the shells of
mollusks, but with minute pores (_foramina_) all over them. From this
character they derived their name _Foraminifera_ or pore-bearers.
[Illustration: FORAMINIFERA.
1. Polymorphina. 2. Textularia. 3. Cristellaria.
]
Within these perforated shells live the amæba-like animals, and
through all these minute pores they protrude still more minute threads
or wisps of their living jelly to use as limbs wherewith to pull
themselves along, and to catch their food. There is a very ancient
conundrum which asks: “What is smaller than a mite’s mouth?” a mite
being formerly considered to be the least of all animals and a very
minute thing indeed; therefore, to imagine the mouth of a mite was to
conceive of something so very small as to be almost beyond conception.
But then came the answer: “That which goes into it!” Of course, if a
mite had a mouth it must have it for the purpose of eating, so that
though nothing were known smaller than a mite, yet a mite must have a
mouth, and that could scarcely be quite as large as the mite, and its
food must be smaller than its mouth. A naturalist would say that this
line of reasoning is weak, and it undoubtedly is so, for there are
creatures that contrive to swallow things that are much larger than
their mouths; but there is no occasion to split hairs just now. These
Foraminifera are in some cases invisible to the unassisted vision, but
as each is pierced with many pores, it follows that the individual
pore must be almost inconceivably small, though still smaller are the
wisps of jelly that protrude through them and invest the outside of the
shell. For it must not be supposed that these structures are secreted
like the shell of the snail, that the animal may live within it; rather
it is like our own skeleton, built up within our bodies.
Some of these shells have but one chamber, like _Lagena_, which is
flask-shaped, and _Entosolenia_, in which the long neck of the flask
has been pushed down inside the globose portion. Others have many
compartments, but these are subject to great variety of arrangement,
each species having its own special form. _Dentalina_ has the
chambers placed one behind the other in a straight or curved line. In
_Nonionina_, _Polystomella_, _Rotalina_, _Globigerina_, and others
they are rolled in a spiral, and resemble the chambered shell of the
Nautilus; or they may be twined, _not_ spirally, round an axis, each
making a half-turn.
[Illustration: POLYCISTIN.]
In some respects similar to the Foraminifera are the Polycistina, which
are equally minute creatures, whose skeletons are of flint instead of
chalk, and the perforations are so large and so close together that
the term pore no longer adequately expresses their proportionate size.
They are more like windows, but with little intervening stonework. The
jelly-substance, called _sarcode_, flows out through all these windows
in the form of threads (called _pseudopodia_ or false feet) as in the
Foraminifera, spreading over the outer surface and acting as legs and
arms by means of which the creature moves and captures its food. They
feed upon infusoria of various kinds, and the diatoms and desmids,
which appear to be paralysed by contact with the pseudopodia. They
also seem to derive part of their nutriment from the exertions of some
minute yellow-bodies, a species of algæ (_Xanthellæ_) that are lodgers
within their substance. These lowly plants, which have sometimes been
incorrectly alluded to as parasites, elaborate starchy products by the
aid of their chlorophyll, and on their death this material is available
for the nutrition of the Polycistin, which also can make use of the
oxygen given off by the plant.
There is one of these low forms of life in which almost all visitors
to the sea-shore take an interest--or rather they are interested in
certain signs of its vital activity--the mysterious phosphorescence of
the sea. There is no moon visible, the sea is quiet, and our reader
late in the evening takes a stroll along the edge of the waves, “before
turning in.” He is charmed to see the ripples as they break upon the
shore brightly outlined with glow-worm light, and stays long to enjoy
the elfish illumination. Now my advice is, do not stay long, but hasten
back to your “diggings” and get a bottle; then return and fill it with
sea-water at a spot where the phosphorescence is most abundant. You can
then examine the creature that produces the strange light.
If now you continue your stroll along to that part of the sea-wall
where the male villagers most chiefly congregate to spin yarns with
a more or less saline flavour, and to discuss village politics, you
will probably hear them talking about fishing prospects, and if it is
in early summer, mackerel will be in their talk. “Well,” says one,
“there’s no doubt the fish are about, and I propose that we get the
sean-boats ready, and to-morrow night we’ll try the briming.” The
meaning of which dark saying is that to-morrow evening they will row
across the bay till they come under the shadow of the great headland,
and there they will adapt the focus of their eyes to seeing below
the surface of the crystal waters, and watching for the streaks of
phosphorescent light that break from the fins and tails and scales of
the mackerel as they pass through the sea. This light is the “briming”
of the fishermen. It is due to the movement of the fish exciting the
light-producer, just as in a marine aquarium in a dark room you can
produce a similar effect by blowing the surface of the water into
ripples. The six long oars of the big sean-boat every time they dip
into the water send a spray of light into the air, and as they again
leave it a shower of glowing pearls drops from each. The prow of the
boat sends up a fountain of pale heatless fire on either side, and an
ever-widening track of the same mysterious light marks the way the boat
has come.
All these brilliant effects are produced by millions of a tiny
Infusorian, individually so small that twenty of the finest specimens,
placed closely together in Indian file, would only produce a procession
one inch in length, whilst of mediocre examples it would require from
fifty to eighty to cover the same space. Its size may be insignificant,
but it has a name which will at least inspire respect with some
persons--_Noctiluca miliaris_--which may be Englished as the Sea
Night-light. If now we go together to your lodgings and examine that
bottle of sea-water with a lens we shall be able to make out a large
number of these creatures swimming about, and by means of a pipette
or dipping tube we can isolate a specimen and place it under the
microscope. There it is revealed to us as a peach-shaped individual,
the spherical mass being partly mapped into two lobes by the slight
groove that, as in the peach, runs down from the depression in which
the stalk is attached. The stalk in this microscopic night-light is
represented by a long flexible tentacle, or _flagellum_, by means
of which _Noctiluca_ moves through the waters, much as a fisherman
will propel his boat by the skilful use of a single paddle at the
stern. There is a shell-like envelope of transparent material through
which may be seen a meshwork of granular material, denser than the
body-mass. A funnel, opening near the _flagellum_, becomes lost in
this granular matter; this is the creature’s mouth and gullet, within
which lies a smaller flagellum. The gullet simply opens into the
central protoplasm; no continuing alimentary canal has yet been made
out. Reproduction is effected by several methods: one is the division
of the creature transversely into two, each complete, but for the time
smaller; a second method is the conjugation of two individuals and
the subsequent breaking up of the protoplasm into numerous spores,
each provided with a flagellum. But this breaking up process may occur
independently of conjugation. The spores move by the lashing of the
flagellum, and gradually develop into the adult form. The light is
produced in flashes just under the clear cell wall, and pure sea-water,
rich in oxygen, is necessary for its continued brilliancy. At times,
on summer evenings, _Noctiluca_ is extremely abundant in the littoral
zone, and it is then impossible to take up a glass of water without
getting thousands of specimens.
If you occasionally indulge in boating, many forms of low life, or the
larval condition of higher forms may be obtained without difficulty.
Take a piece of thin, round cane--about the thickness used in training
a child in the way he should go--and bend it into a hoop. The two ends
should be cut half through for an inch of their length, so that their
flat surfaces can be brought together and secured by several turns
of a piece of thin copper wire. Now to this cane secure a small flat
piece of lead, so that when thrown into the water the hoop will assume
an erect position. If you should have a couple of inches of “compo”
gas-tubing handy, this will do admirably, and may be slipped over the
cane before the ends are lashed together. Upon the hoop now stitch a
muslin bag to serve as a net; and to three or four equi-distant points
on the frame attach short, strong strings of equal length, and join
their ends to a length (say three fathoms) of fishing line. This may
be made fast to one of the thwarts of the boat, or held in the hand,
whilst the net is thrown overboard. The movement of the boat will cause
the net to collect a large number of minute creatures that float on
the surface or immediately below it. From time to time it should be
hauled in, and the bag turned inside out and washed in a glass jar of
sea-water. In this way many interesting forms may be secured. A calm,
sunny afternoon should be selected for this work, and the boat should
be rowed gently.