THROUGH A MICROSCOPE
BY MARY TREAT
IX.--THE UTRICULARIA.
It seems strange that innocent-looking plants should capture and kill
animals; but this is really what the Bladderworts (_Utricularia_) are
all the time doing. They grow in ponds and swamps, some species in deep,
still water, others in shallow ponds.
Fig. 1 shows a portion of the stem of _Utricularia clandestina_, natural
size. The little bladders are so nearly transparent, that on bringing
them under the microscope, or even under a good lens, you can see the
numerous creatures that they have captured, some partly consumed, others
still alive.
The bladders on these curious plants remind one of some of the
_Entomostracans_ which Mr. Wells described in his fourth paper. Look at
_Chydorus sphericus_ for instance, and then at the magnified bladder
(_Fig. 2_) in this article. The branched horns at the mouth or entrance
have very much the appearance of the antennae of some of the minute
animals, and the stem when it is attached to the main branch may be
likened to a tail. But the way in which they capture and devour the
pretty little creatures that come within their grasp makes them appear,
even more than they look, like wicked animals.
[Illustration: FIG. 1. PORTION OF A STEM OF UTRICULARIA CLANDESTINA;
NATURAL SIZE.]
I have found almost every swimming animalculae with which I am
acquainted, caught in these vegetable traps; and when caught they never
escape. Their entrance is easy enough; there is a sensitive valve at the
mouth of the bladder, which, if they touch it, flies open and draws
them in as quick as a flash. These downward-opening bladders not only
entrap animalculae, but, more wonderful still, the strong larvae of
insects. The larvae most frequently caught are those of the mosquito and
chironomus. Often the mosquito is caught tail first--the entire body
inclosed and the head left sticking out. It always looks as if the
victim might walk or wriggle out, but it never does; and you may be sure
that it never backed in there of its own accord.
You all know how the mosquito larva wriggles in the water, and is known
by the common name of "wriggler," or sometimes inaccurately, "wiggler."
Now just as sure as the tail of this wriggler strikes the mouth of the
bladder, just so sure is he caught--drawn in by some unknown power
quicker than you can speak.
There is yet much to learn about these curious plants. How it is that
the valve or trap can so firmly hold these strong larvae is still a
mystery. I have seen a mosquito larva caught by the head when the first
joint of the body was too large to be admitted through the entrance of
the bladder, and have patiently watched its frantic efforts to escape,
but it was never released. The more it thrashed about, the tighter grew
the fatal trap until death put an end to its struggles.
The chironomus larva is quite unlike that of the mosquito. The
chironomus has brush-like feet which it can withdraw from sight--a sort
of telescopic arrangement--or extend when it wishes to crawl along the
plants, while the mosquito wriggles and swims.
The chironomus is caught more often even than the mosquito larva. At
certain seasons of the year it is almost impossible to find a bladder
without one or more of these victims entrapped.
They feed on the water plants, and seem to have a special liking for the
long-branched antennae which grow at the mouth of the bladders, and, all
unconscious of the trap, on, on they go, their sickle-shaped jaws
cutting the antennae which they eat as they advance, until their heads
reach the mouth of the bladder, when they heedlessly touch the valve and
the trap is sprung and they are drawn within, never more to escape, but
to be slowly devoured.
There is another interesting species of _Utricularia_, the _Purfurea_,
quite different in many particulars from the first. It grows in deep,
still water. The stems are long, sometimes two feet or more in length,
and the branches radiate in every direction, so that one plant often
covers quite a large surface of water. The flowering stems stand above
the water, and each stem bears three or four very pretty violet purple
flowers, and it blossoms nearly all summer.
[Illustration: FIG. 2. BLADDER OF U. CLANDESTINA MAGNIFIED TWENTY
DIAMETERS.]
The flowers are about half an inch broad and quite conspicuous. Most of
the other species have yellow flowers.
There are no little thread-like leaves on this species, and the bladders
are on the ends of the little branchlets, and they have no sharp-pointed
antennae as in the other species; but in their place is an elegant
cluster of transparent glassy-like ornamental appendages. The ornaments
are just above the entrance, and who knows but this is a contrivance set
there to lure unwary creatures into the trap.
One of the most common little creatures that was caught in this trap,
was the _Tardigrada_, or water bear. He looks like a tiny cub, but
unlike his great namesake, he has eight legs, and he frequently slips
out of his old skin and comes out in a new suit.
I often find them crawling in a forest of these plants, peering out of a
thick jungle--now ascending a branch and out on a limb, holding fast
with their long claws, and apparently looking around to see what they
can find.
Now one seems to be attracted to this elegant glassy cluster of
_Utricularia_. At all events he is soon pushing his head among the
delicate stems, then stops a moment, standing perfectly still as if
listening. Perhaps he hears the groans of his dying comrades, but all
unheeding the warning, he steps forward, touches the fatal spring, when
in he goes to perish with his comrades.
[Illustration: FIG. 3. CHIRONOMUS LARVA: BACK VIEW WITH FEET DRAWN IN
AND JAWS CLOSED; SIDE VIEW WITH FEET EXTENDED AND JAWS CLOSED.]
Young microscopists may like to know that the _Utricularia_ can be
preserved in the house a long time by putting the stems or sprays in an
open, shallow dish of water where they will grow readily. I have kept
the plants months together in a large glass dish where they looked
charmingly beautiful and were the admiration of all who saw them. It is
very interesting to watch their growth. The ends of the growing sprays
unroll like ferns, and with a magnifying glass you can see the
development of the little bladders, and you may make discoveries--who
knows? I know that for a long time it was a mystery to me how the
bladders captured and imprisoned the little animals. Every day I saw
they were entrapped and never escaped, and I studied and pondered over
the matter a long time, and was so interested and determined to learn
the secret that I spent night after night looking through the
microscope, watching the strange, unwary creatures fall into the trap.
At last I concluded to adopt the following plan: I took sprays of the
plants that I had grown in clear water that contained no animalcules, so
that all the bladders were empty and quite transparent. In another dish
I had put a great many masses of mosquito eggs. Mosquito eggs are found
floating on almost any standing water, in dark, compact masses. In warm
weather they hatch in a few hours. So you can understand how quickly I
could swarm a small vessel of water with the mosquito larvae by
introducing the eggs where I wished them to hatch. When they were
hatched I put some of the water in which was a large number of the tiny
creatures into the live box with a spray of the plant containing empty
bladders. I placed the box under the microscope and closely watched the
manner of capture. I became certain that in almost every instance the
larvae were caught tail first. The tail is brush-like, and when it swept
over the door or valve that leads into the bladder, I saw that the door
would immediately fly open and always draw the larva in. I soon became
satisfied that the valve was very sensitive when touched at the right
point, but to this day I cannot tell what the power is that so quickly
draws the creatures within. I earnestly hope that some young
microscopists will yet be able to ferret out the cause of this singular
power.
Those who have read Mr. Darwin's very interesting book on _Insectivorous
Plants_, will have noticed that he says the valve of _Utricularia_ is
not in the least sensitive, and that the little creatures force their
way into the bladders--their heads acting like a wedge. But this is not
the case, as Mr. Darwin himself was convinced some years before his
death. In his usual kind, gracious manner he admitted that he was wrong,
and gracefully says the valve must be sensitive, although he could never
excite any movement. In a letter to me bearing date June 1st, 1875, he
says:
"I have read your article (in _Harpers Magazine_) with the greatest
interest. It certainly appears from your excellent observations that the
valve is sensitive.... I cannot understand why I could never with all my
pains excite any movement. It is pretty clear I am quite wrong about the
head acting like a wedge. The indraught of the living larva is
astonishing."
X.--FREE SWIMMING ANIMALCULES.
The Brickmaker, Floscules, and Vorticellas are quiet peaceable citizens
of the microscopic world, and seem to be impressed with the graver
duties of life; they set up housekeeping and settle down for life moored
to one spot. But there are many others that live a free-and-easy sort of
life--a wandering gypsy kind of an existence, always on the move; and
there is not much satisfaction in trying to follow these rovers if we
wish to make a careful study of their structure.
[Illustration: SKELETON WATER WHEEL.]
So to be enabled to examine them you will be compelled to imprison them
in the live-box and bring just as much pressure to bear upon them as
they will stand without crushing, which with careful practice you may
soon learn to do. But if you are simply making the acquaintance of these
little creatures for amusement, it is more interesting and satisfactory
to watch them while they are unrestrained, and see the curious feats
they perform.
One of the most amusing of these little animals is the Skeleton
Wheel-bearer (_Dinocharis pocillum_). His portrait is seen at _Figure
1_. He has a long foot consisting of three joints, and these joints are
as perfect as those of our own knees and elbows, and can be moved as
easily forward and sideways, but not backward. The joints and foot are
not covered with any fleshy substance, from which fact--the joints being
so conspicuous--it probably received the name Skeleton. Two long slender
toes extend from the last joint, and from the tips of these the Skeleton
can show us more wonderful feats than any circus performer.
The toes can be widely separated, or brought close together, like a pair
of tongs. Sometimes he stands on the tip of one toe and throws his body
forward, or from side to side with a rapid motion; then straightening
himself up, he stands on the tips of both toes as if posing, remaining
perfectly still for a few moments and giving us an opportunity to take a
good look at his curious body which is encased in a pretty vase-shaped,
three-sided transparent shell. The head extends from the top of the
vase, and is surmounted with the usual cilia, or wheel, which we see
among all the rotifera. When he is tired of posing, away he swims in a
graceful, easy manner, with his long foot straightened out and the toes
brought close together.
You sometimes will find these pretty creatures, especially in
summer-time, very numerous in the sediment at the bottom of your
collecting bottles. Often I have found dead specimens, and very
beautiful objects they sometimes are. Great numbers of tiny scavengers
have completely cleaned out all of the soft parts of the body in a most
neat and perfect manner, leaving the beautiful shell and vertical
column, that runs through it, and the foot and toes, entire and perfect
in all of their parts.
Think of the minuteness of these scavengers--untold numbers of them
preying upon the body of an object invisible to the naked eye; and yet
this body is a mammoth by the side of one of the scavengers! The mind
can scarcely grasp the minuteness of these tiny creatures--creatures
that seem to enjoy existence, eating, and apparently playing and
entertaining each other like the higher animals.
[Illustration: WHIPTAIL.]
The whiptail (_Mastigocerca carinata_) (_Fig. 2_) is another delicate
pretty little creature, and, like the skeleton, is encased in a glassy
shell. It has a long, tapering, spine-like foot, or, more properly
speaking, a toe which is attached to a very short foot by means of a
flexible joint which allows free motion. You often will find him in
company with the Skeleton, and they seem to vie with each other in
performing strange feats. The Whiptail, if possible, looks even more
comical than the Skeleton when it stands on the tip of its long toe, a
toe which is longer than the entire length of the body, now bending over
and nibbling at the plants, now whisking around as if looking and
inquiring into some passing object, then sailing through the water with
a graceful, easy motion beyond sight.
_Brachionus pala_ is also a lovely creature encased in a delicate
transparent shell. It is considerably larger than the Skeleton or
Whiptail, and is just visible to the unassisted eye. If you drop it in a
phial of clear water and hold it up to the light, you can distinctly see
it gliding through the water like a revolving white speck. A moderate
power of the microscope reveals its beauty. The shell is swelled at the
sides, and narrow at the mouth, and round over the back, while the under
side is flat.
[Illustration: LARGE ROTIFER.]
Like the Skeleton and Whiptail, the head of the little Brachion is seen
protruding from the upper part of the shell; but instead of one wheel
this charming little creature has two, and nothing can be more lovely
than a sight of these fast revolving wheels, like two beautiful crowns.
The reason the wheel looks so strikingly beautiful in _Brachionus_ is
owing to the long cilia which is longer in this genus than in other
genera of this great family.
The foot of _Brachionus_ is more curious than that of the Skeleton. It
is telescopic, and the little animal has the most perfect control over
it. He can draw it within the body so that it looks like a ball, and
again quickly thrust it out and whisk it around in all directions like a
tail. It has two short toes at the end which can be separated or brought
together at pleasure. And he can firmly anchor himself by the toes and
stretch forward, showing you the great length of the foot. Now he rolls
from side to side without letting go his hold and performs other strange
feats, and all the while the wheels are rapidly revolving, he has
stopped his headlong career through the water and has settled down to
get his supper.
_Fig. 3_ represents one of the largest rotifers with which I am
acquainted. I have never been able to find a description or engraving
of it in any work on microscopy. But it is probably well known to
microscopists, for it has a wide range. I have found it in New
Hampshire, New Jersey and Florida.
You cannot get a true idea of its graceful beauty from the drawing, as
it is represented as it was seen in the live box with sufficient
pressure upon it to keep it from moving, while serving as a model. And
no engraving, however perfect, can give you any idea of its brilliant
transparency and delicate coloring.
The play of the muscles and internal organs are plainly visible, and you
can always tell what he has chosen for dinner. Diatoms and desmids form
a portion of his diet. His mouth is below the wheel. When he is hungry
he anchors himself by his forked tail and sets his wheel in rapid
motion, which makes a powerful current sufficient to bring quite large
objects to his head, frequently too large to admit into the mouth. He
will often repeatedly try to take a desmid entirely too large for his
mouth, and his manoeuvres are quite comical as he whirls it round and
round, nipping it on all sides. You will see by looking at the figure
that everything has to be swallowed or taken within the body before it
reaches the mouth. While the desmid is within the body the rotifer has
control over it sufficient to take it into the mouth if it is of the
right size, but if it is too large he soon becomes disgusted and ejects
it with a sudden movement which sends it whirling rapidly away. And now
he takes a smaller one and his jaws work vigorously a moment or two,
when he swallows it almost entire, and we can plainly see the pretty
markings and brilliant green color after it has passed into the stomach.
This large rotifer is plainly visible to the naked eye, and you will
find it in both shallow and deep ponds, wherever water plants grow,
during the months of July and August.
XI.--ON THE BEACH.
Many of our young people spend the month of August at the seaside, and
if those who wish to learn something of the curious microscopic animals
will stroll along the beach when the tide has receded, until they come
to rocky places and little pools filled with salt water and various
marine plants, they will find a form of animal life quite different from
that in fresh water ponds. These little pools along the rocky coast are
the homes of countless numbers of zoophytes--animals which have a
stronger resemblance to plants and flowers than any we have found in
fresh water.
Look for specimens for microscopic work on the surface of the rocks, on
dead sea shells, and on the sea-weeds. On the sea-weeds you will often
find a white filmy network which to the unassisted eye looks like simple
white threads running and spreading in every direction, and at every
angle of the network a tiny stem shoots up, branching out like a tree
and making a miniature forest.
Now if you apply a low power of the microscope, you will find the little
forest is made up of a strange animal called _Laomeda geniculata_.
(_Fig. 1._) Each branch of this compound animal terminates and expands
into a lovely vase and is the home of a polype. The polype is not a
separate individual any more than the end of a growing branch is
separate from the tree on which it grows.
[Illustration: LAOMEDA.]
When the creature is hungry he sends out from the margin of the vase
from fifteen to twenty tentacles, ranged around the rim like the petals
of a flower. _Figure 1_ shows one of these expanded polypes as seen
through the microscope.
The tentacles or feelers are fishing rods to bring game to the fleshy
mouth which is protruded from the centre of the vase. A great many such
mouths surrounded with their tentacles are necessary to feed this
singular compound creature.
All that I can tell you of these microscopic animals will be nothing
compared to a study of them with your own eyes, so I will only give you
hints of what you may expect, thereby hoping to create sufficient
interest to induce you to stroll to out-of-the-way places, where you may
find many of Nature's marvellous works. We want more field workers in
every department of Natural History, and especially in microscopy where
unexplored fields are awaiting you.
When the tide has receded, various objects of interest will meet your
eye at every step. Look at that old dead sea shell covered with a rough,
shaggy nap. Ah, as we approach, the shell is moving off! What can it
mean? Why, it means that a hermit crab has set up housekeeping in the
old shell, and he, no doubt, thinks us suspicious characters and wants
none of our company. But we are after microscopic objects now, and this
hermit, interesting as he is, is not to claim our attention to-day. The
rough coat on the outside of the shell is of more interest.
With the aid of a pocket lens you will find it another zoophyte. You
can see the polypes, as thick as they can well stand, rising erect and
straight from the shaggy coat like a miniature field of wheat. With a
higher power you will see that each mouth is surrounded with tentacles
like those of _Laomeda_, but yet it is quite a different looking
creature. If we touch one of these polypes ever so lightly, the great
army immediately close their tentacles, for the same life pervades the
entire colony, and those on the extreme outer edge feel the contact as
quickly as the one we touched.
[Illustration: LARES.]
One of the most comical and amusing creatures of all the zoophyte tribe,
is figured and described by Mr. Gosse under the name of _Lar
Sabellarum_. He was the first observer of this curious creature; he
found it inhabiting the outer edge of the tube of a worm--the Sabella.
So when you are looking for microscopic objects do not overlook any tube
that you may see standing above the surface of sand and mud, as it may
be surrounded by this singular zoophyte. The tubes usually extend an
inch or two above the surface, and about as far below. I have found the
tubes surrounded with the creatures, but not in as good condition for
investigation as those Mr. Gosse mentions. Mine were too thick and
crowded to distinguish clearly. But as Mr. Gosse describes them, they
have a most close resemblance to the human figure as they stand erect
around the mouth of the tube of Sabella.
A loose network surrounds the top of the tube and the strange forms
spring from the angles of the meshes. The creatures are furnished with
heads, and immediately below the head are two arms. (_Fig. 2._) The head
moves to and fro on the neck, while the arms are tossed wildly about as
if gesticulating in the most earnest manner. Or, as in the wild and
disorderly dances of savages the body sways back and forth while the
arms are thrown upward and downward in a frantic way.
One summer I found a colony standing so thickly together that they did
not show off to very good advantage. Apparently they were like a packed
army of Liliputians, striking out with their arms and struggling with
one another. But when I came to observe them more carefully, I found
they were not interfering with one another at all, but each was intent
on his own business of obtaining a livelihood.
[Illustration: HAND OF BARNACLE.]
The Sabella which inhabits the tube, is of itself a most attractive
object. Most elegant fringed filaments proceed from the head, and wave
back and forth like a fan, and near the ends of these delicate slender
filaments are little black balls, supposed to be eyes. If they are eyes,
the Sabella has no lack of vision, and this may account for his seeming
watchfulness. He is always on the alert and drops down into his house at
any approach. Only with the utmost caution will you have an opportunity
to leisurely look at his rare beauty.
When for the first time I saw this elegant, beautiful creature rising
out of the tube, and waving its fringed fan-like filaments, I did not
wonder at Mr. Gosse's enthusiasm. Neither was I surprised that he should
be reminded of the old Roman mythology and call the zoophytes which
surround the tube, "Lares," for the rare beauty of Sabella would suggest
the protection of guardian spirits. He says:
"These curious creatures have afforded much entertainment, not only to
myself, but to those scientific friends to whom I have had opportunities
of exhibiting them. When I see them surrounding the mansion of the
Sabella, gazing, as it were, after him as he retreats into his castle,
flinging their wild arms over its entrance, and keeping watch with
untiring vigilance until he reappears, it seems to require no very vivid
fancy to imagine them so many guardian demons; and the Lares of the old
Roman mythology occurring to memory, I described the form under the
scientific appellation of _Lar Sabellarum_. You may, however, if it
pleases you better, call them 'witches dancing round the charmed pot.'"
When the tide is out you will frequently notice barnacles adhering to
the rocks, or to the timbers used in the construction of wharves. Pray
stop and examine them critically and see what admirable fishers they
are. Their fishing-nets are composed of several long, flexible, jointed
fingers, thickly beset with sensitive hairs. When the fisher wants a
meal he thrusts his long hand (_Fig. 3_) out the door of his stone
house; the sensitive fingers quickly tell when they come in contact with
anything good to eat, and they curl over and grasp it and convey it to
the mouth.
These barnacles are wonderful creatures and well worthy your continuous
study. They pass through several stages. When young they are a gay
rolicking set, swimming freely in the water; but as maturity approaches
they settle down in stone houses, never more to rove about, and set up
fishing for a living.
XII.--RHIZOPODS.
Rhizopods are the lowest creatures in the animal kingdom. Some of them
are apparently nothing more than animated protoplasm. Protoplasm
pertains to the first formation of living bodies, whether vegetable or
animal, and it appears to be only a viscid, glutinous, unformed mass of
jelly-like substance, yet these rhizopods seem endowed with something
more than simple life.
[Illustration: FIG. 1. AMOEBA PRINCEPS, IN DIFFERENT FORMS.]
Let us take the lowest of these lowly creatures, the _amoeba_, or
proteus, which we may find during the summer in almost every fresh water
pond. I cannot describe it, for, like its namesake, it is constantly
changing its form, slipping away from us, as it were, right before our
eyes, and assuming a new shape. As Proteus of old could assume any form,
either plant or animal as he pleased, so our _amoeba_ can assume
various forms at pleasure.
You will remember that Homer introduces Proteus in the fourth book of
the _Odyssey_. He makes him the servant of Neptune, and says his office
was to take care of the seals or sea-calves. And who knows but his
namesake may have some such office among the curious beings of the
microscopic world which is peopled with as many strange creatures as
those we read of in ancient mythology?
We frequently see our proteus adhering to a leaf of some water plant
when it looks like a little ball of jelly; and while we are looking at
it, it pushes out an arm here, and now another there, and still another,
as if feeling for something. (_Fig. 1, Amoeba princeps._) Not finding
anything to its taste, it moves or crawls along with its temporary arms
extended--all the while changing them, throwing one out on this side,
then on that, then contracting and pushing out in another place. It
seems to be actively in search of something. At last it has reached a
moving diatom with one of its long arms, which it immediately wraps
around it, and now the other arms are contracted and the creature
actually folds itself around its dinner! He turns himself outside in,
and makes a temporary stomach, and proceeds to digest the soft parts of
the diatom. After he has extracted all the nourishing part, he squeezes
or pushes out the clear, transparent shell, and starts in search for
something more.
It is not known to a certainty how the _amoebae_ are produced, but this
much is known: If a portion of the body is detached from the rest, it
does not die, but becomes an independent _amoeba_. If a portion of one
of the arms becomes separated from the main body, it does not seem to
incommode the creature in the least, and the small part soon begins to
extend tiny arms and behave in every way like its parent. And this may
be the only way in which the children of Proteus are made--veritable
children of his own flesh.
How strange it seems that a jelly-like mass of substance without form or
organization should be endowed with life and sufficient sense to go in
search of food and have the power of selection.
Life manifested in the lowest animal or plant is just as wonderful and
hard to understand as that which pervades the higher animals.
Some of the species of the fresh water _amoeba_ live in shells of
various forms and patterns. One which we often see has a little house
made of tiny particles of sand and minute bits of shell soldered
together with a kind of cement which hardens in water; these are vase or
pitcher-shaped and always look rough on the outside.
[Illustration: FIG. 2. TESTACEOUS FORMS OF AMOEBAN RHIZOPODS.]
We may always know the different species by the forms and patterns of
the shells in which they live. Some have very regular shells and
prettily marked. These are usually rounded or arched on one side and
flat on the other.
When you are looking for various microscopic objects in pond water you
will often see these tiny shells among the sediment on your slides, and
if you will patiently wait a few moments you will soon see delicate,
transparent arms slowly pushing out on every side like cautious feelers.
(_Figure 2, Amoeba in Shell._--_Carpenter_, p. 445.)
But the most beautiful forms, and by far the greatest variety of these
microscopic shells are found in the ocean and in marine deposits. If we
look at the seaweeds which grow on the rocks we may see many white
specks adhering to every part of the plants. With a lens we find the
minute specks are spiral shells of many species belonging to the class
_Foraminifera_, and very closely allied to the _amoeba_. The shells
are of most elegant form and pattern. The large sea-shells which we so
much admire are not half so lovely in form or color as these seen
through a microscope. Some of the living animals and the castles in
which they dwell are crimson in color, others a delicate pink.
Let us take one of these living shells while it clings to the sea-weed
and carefully cut off the smallest portion of the plant to which it
adheres, so as to disturb the occupant as little as possible; and now
place it in the live box with some of the salt water and we shall soon
have a most beautiful sight.
See, the creature is throwing out delicate, transparent threads or
filaments in every direction, like fine-spun glass. How charming it
looks with the beautiful shell in the centre, surrounded by this moving,
filmy halo, and how slowly and cautiously the filaments are extended! He
is not a heedless, reckless creature, rushing into needless danger, but
a quiet, timid citizen. Although he was such a long time throwing out
his misty arms, when he scents danger he withdraws them as quick as a
flash. The least jar of the live-box, or a little wriggling larva--much
too large for him to manage, however--are sufficient to make him take in
all of his lines; but when quiet is restored, they are again stretched
out. And for what purpose are these slender filaments extended? Ah, an
innocent animalcule has become entangled among the shimmering, filmy
threads, and now the threads coalesce, run together like the arms of
_amoeba_, and disappear, and the animalcule is drawn within the walls
of the beautiful castle, and we are left to conjecture the fate of the
little victim. _Figure 3, Rotalia Ornata_--which shows its delicate
filaments extended.
These tiny creatures have been so numerous way back in the early ages of
the world, that entire strata of rocks, several feet in thickness, in
various parts of the world, are made up of their skeletons. The city of
Richmond, Virginia, is built over rocks, composed largely of the minute
fossils of _Diatomaceae_ intermingled with the _Foraminifera_ and others.
[Illustration: FIG. 3. ROTALIA ORNATA.]
A single prepared slide of these fossils will afford entertainment for
an entire evening, so great is the diversity of form and so many
hundreds on one slide. The Bahama Islands furnish the finest specimens
of these fossils. The slides can be procured of any large dealer in
optical instruments, or, what is still better, the young microscopist
can soon learn to prepare them for himself, as ample directions are
given in the books on the microscope.
In bidding my young readers adieu I shall not lose entire thought of
them, but often when I am engaged in looking through the microscope, I
shall think and ask myself, "Are they, too, absorbed in this pleasant
work, and how many will become true workers and original investigators
in this great field?" We shall all know in due time, for no earnest
worker in any branch of science can long remain unknown. He will be
found out sooner or later. A devoted student in microscopy will become
so happy over the marvellous creatures and their curious ways that he
cannot keep his pleasure to himself.