Watch her closely and see how she gets the nectar. Notice how she
“bumbles around” in a flower and becomes dusted with pollen. Watch
her and note how she gets the pollen off her fur and packs it in her
pollen baskets. On which legs are her pollen baskets? How does the
pollen look when packed in them? What does she do with pollen and
nectar?
2. Catch a bumblebee in a jelly glass and look at her closely. Can
you see three little eyes between the big compound eyes? Describe her
antennæ. Are they active? How many pairs of wings has she? Do you
think they are strong? Which pair of legs is the shortest? How many
segments are there in the leg? Do you see the claws on the foot?
3. What is the bumblebee’s covering? What is the color of her plush?
Is she furry above and below?
4. Can you see that she can bite as well as suck with her
mouth-parts? Will a bumblebee sting a person unless she is first
attacked?
5. Have you seen the very large queen bumblebee in the spring, flying
near the ground hunting for a place to build a nest? Why must you be
very careful not to hurt her? How does she pass the winter? What does
she do first, in starting the nest?
6. In how many ways does the bumblebee benefit us?
[Illustration]
THE HONEY-BEE
_Teacher’s Story_
[Illustration: D]
During many years naturalists have been studying the habits and
adaptations of the honey-bees, and, as yet, the story of their
wonderful ways is not half told. Although we know fairly well what
the bees do, yet we have no inkling of the processes which lead to
a perfect government and management of the bee community; and even
the beginner may discover things never known before about these
fascinating little workers. In beginning this work it might be well
to ask the pupils if they have ever heard of a republic that has many
kings and only one queen; and where the citizens do all the governing
without voting, and where the kings are powerless and the queen works
as hard and longer than any of her subjects; and then tell them that
the pages of history contain no account of a republic so wonderful
as this; yet the nearest beehive is the home of just this sort of
government.
In addition to the interest of the bee colony from a nature-study
standpoint, it is well to get the children interested in bee-keeping
as a commercial enterprise. A small apiary well managed may bring
in an acceptable income; and it should be the source of a regular
revenue to the boys and girls of the farm, for one hive should net
the young bee-keeper from three to five dollars per year and prove a
business education to him in the meantime.
Bees are perfect socialists. They have non-competitive labor, united
capital, communal habitations and unity of interests. The bee commune
is composed of castes as immutable as those of the Brahmins, but
these castes exist for the benefit of the whole society instead of
for the individuals belonging to them. These castes we have named
queens, drones and workers, and perhaps, first of all, we should
study the physical adaptations of the members of these castes for
their special work in the community.
_The Worker_ (p. 446, Fig. 3.)
There are three divisions to the body of the bee, as in all
insects--head, thorax and abdomen. The head bears the eyes, antennæ
and mouth-parts, (p. 448, W.) There are two large compound eyes on
either side of the head and three simple eyes between them. The
antennæ arise from the face, each consisting of two parts, one
straight segment at the base, and the end portion which is curved and
made up of many segments. There is also a short, bead-like segment
where the antenna joins the face. A lens is needed to see the jaws
of the bee, folded across, much like a pair of hooks, and below them
the tongue, which is a sucking tube; the length of the tongue is very
important, for upon this depends the ability of the bee to get nectar
from the flowers.
The thorax bears three pairs of legs below and two pairs of wings
above. Each leg consists of six segments, and the foot or tarsus has
four segments and a pair of claws. The front leg has an antennæ comb
between the tibia and tarsus, (p. 447, F, a,) the hind leg has a
pollen basket, which is a long cavity bordered by hairs wherein the
pollen is packed and carried (p. 447, A, pb.) On the other side of
the large joint beyond the pollen basket are rows of spines which
are used to remove the pollen from the baskets (p. 447, B, pc), and
between these two large segments are the pincers for removing the wax
(p. 447, B, wp.)
The front pair of wings is larger than the hind pair. The wings of
the old bees that have done much work are always frayed at the edges.
There are six segments or rings to the abdomen, plainly visible from
above. If the five segments next the thorax are marked above with
yellow bands on their front edges, the bee is an Italian. On the
lower side of the abdomen, each segment is made up of a central plate
with an overlapping plate on each side; just at the front edge on
each side of the central plate is a wax pocket which cannot be seen
unless the bee is dissected under a microscope. From these pockets
are secreted little flecks of wax (p. 448, X.)
_The Queen_
[Illustration:
_1. Queen bee._ _2. Drone._ _3. Worker; all enlarged._
_4. Queen cells._
From How to Keep Bees--Comstock.
Drawn by A. J. Hammar.]
The queen bee is a truly royal insect. She is much larger than the
worker, her body being long, pointed, and extending far beyond the
tips of her closed wings, giving her a graceful form. She has no
pollen baskets or pollen comb upon her legs, because it is not a part
of her work to gather pollen or honey. The queen bee starts life as
an ordinary worker egg, which is selected for special development.
The workers tear down the partitions of the cells around the chosen
egg and build a projection over the top, making an apartment, (p.
446, Fig. 4.) The little white bee grub, as soon as it hatches, is
fed for five days on the same food as is given to the worker grubs
for three days; it is a special substance, secreted by the worker
bees, called royal jelly. This food is very nourishing, and after
being reared upon it, the princess larva weaves around herself a
silken cocoon and changes to a pupa. Meanwhile the workers have
sealed her cell with wax.
[Illustration: _Legs of worker honey-bee._
_A, outer surface of hind leg showing the nine segments and
claws_; _pb, the pollen basket of tibia_; _B, inner surface
of part of hind leg_; _wp, wax-pincers_; _pc, pollen-combs_;
_C, inner surface of part of hind leg of queen_; _D, inner
surface of part of hind leg of drone_; _E, part of middle
leg of worker_; _s. spur_; _F, part of fore leg showing the
antenna cleaner a_; _G, part of antenna showing sense-hairs
and sense-pits_.
From How to Keep Bees--Comstock.
Drawn by A. J. Hammar.]
When the princess-pupa changes to the full-grown queen she cuts a
circular door in the cover of the cell and pushes through it into
the world. Her first real work is to hunt for other queen cells and
if she finds one, she will, if not hindered, make a hole in its side
and sting to death the poor princess within. If she finds another
full-grown queen, the two fight until one succumbs. The queen never
uses her sting upon anything or anyone except a rival queen.
After a few days she takes her marriage flight in the air, where
she mates with some drone, and then returns to her hive and begins
her great work as mother of the colony. She runs about on the comb,
pokes her head into a cell to see if it is ready, then turning about
thrusts her abdomen in and neatly glues an egg fast to the bottom.
When the honey season is at its height she works with great rapidity,
sometimes laying at the rate of six eggs per minute, often producing
3,000 eggs during a day, which would equal twice her own weight. If
the workers do not allow her to destroy the other queens, she then
takes a portion of her colony with her and swarms out, seeking a home
elsewhere.
[Illustration: _D, head of drone_; _Q, head of queen bee_; _W, head
of worker_; _X, worker bee seen from below, showing plates of wax
secreted from wax pockets_.
From How to Keep Bees--Comstock.
Drawn by A. J. Hammar.]
_The Drone_
The drone differs much in shape from the queen and the worker. He is
broad and blunt, being very different in shape from the queen, and
larger than the worker, (p. 446, Fig. 2.) He has no pollen baskets on
his legs and has no sting. His eyes are very much larger than those
of the queen or the worker and unite at the top of the head (p. 448,
D.) His wings are larger and stronger than those of the worker or
queen. It is not his business to go out and gather honey or to help
in the work of the hive. His tongue is not long enough to get honey
from the flowers; he has no pollen basket in which to carry pollen;
he has no sting to fight enemies and no pockets for secreting wax; he
is fed by his sister workers until the latter part of the season when
the honey supply runs low, and then he is stung or bitten to death
by these same sisters who have always given him such good care. The
drone should be called a prince or king, since his particular office
in the hive is to mate with the queen.
_References_--How to Keep Bees, Comstock; The Bee People, Morley.
LESSON CIII
THE HONEY-BEE
_Leading thought_--In a colony of honey-bees there are three
different forms of bees, the queens, the drones, and the workers. All
of these have their own special work to do for the community.
_Method_--In almost every country or village community there is an
apiary, or at least someone who keeps a few colonies of bees; to
such the teacher must turn for material for this lesson. If this
is not practical the teacher may purchase specimens from any bee
dealer; she may, for instance, get an untested queen with attendant
workers in a queen cage sent by mail for a small sum. These could be
kept alive for some time by feeding them with honey, during which
time the pupils can study the forms of the two castes. Any apiary
during September will give enough dead drones for a class to observe.
Although ordinarily we do not advocate the study of dead specimens,
yet common sense surely has its place in nature-study; and in the
case of the honey-bee, a closer study of the form of the insect is
desirable than the living bee might see fit to permit. There are no
more wonderful instances of adaptation of form to life than is found
in the anatomy of the workers, queens and drones; moreover, it is
highly desirable if the pupils are ever to become bee-keepers, that
they shall know these adaptations.
A lens is almost necessary for these lessons and a compound
microscope used with a low power would be a very desirable adjunct.
This lesson should not be given below the fifth grade; and it is
better adapted to eighth grade work.
_The Worker_
_Observations_--1. How many divisions of the body are there?
2. What organs are borne on the head?
3. Are there small, simple eyes between the large compound ones?
4. What is the difference between the large eyes and the small?
5. Describe the antennæ.
6. What can you see of the mouth? Describe it.
7. Look at the tongue under the microscope and see how it is fitted
for getting nectar from flowers.
8. What organs are borne on the thorax?
9. Study the front or middle leg. How many joints has it?
10. With a lens find the antennæ cleaner on the front leg. Describe
it.
11. Describe the feet and claws.
12. Compare the third segment of the hind leg with that of the front
leg.
13. Note that this segment of the hind leg is much wider. Note its
form and describe how it forms the pollen basket.
14. Study the next segment of the hind leg, and note the wax pincers
and the pollen combs.
15. Compare the front and hind wing as to shape and size.
16. How many rings are there on the abdomen and how are the rings
colored above.
17. Study the lower side of the body; do you know where the wax comes
from?
18. Write an English theme on the development of the larva of the
worker bee; the duties of a worker bee from the time it issues from
its cocoon until it dies working for the colony.
_The Queen Bee_
1. How does the queen differ in size and shape from the worker?
2. Has she pollen baskets or pollen combs on her hind legs?
3. How does the shape of the abdomen differ from that of the worker?
4. Write an English theme on the life of a queen bee. This should
cover the following points: The kind of cell in which the queen is
developed; the kind of food on which she is reared; the fact that she
never stings people but reserves her sting for other queens; why she
does not go out to gather honey; how and by whom and on what she is
fed; she would not use pollen baskets if she had them; the work she
does for the colony; the length of her life compared with that of
a worker; the time of year when new queens are developed, and what
becomes of the old queen when a new one takes her place; why she is
called a queen.
_The Drone_
1. How does the drone differ in size and form of body from the worker?
2. How does he differ in these respects from the queen?
3. Has he pollen baskets on his legs?
4. Has he a sting?
5. Compare his eyes with those of the queen and worker.
6. Compare the size of his wings with those of the queen and worker.
7. Write an English theme on the drone. This should cover the
following points: In what sort of cell is the drone developed; does
he go out to gather honey or help in the work of the hive; how he
is fed; how he is unfitted for work for the colony in the following
particulars: Tongue, lack of pollen baskets, lack of sting, and of
wax pockets; why the drone should be called a prince or king; the
death of the drones; when and by what means it occurs.
HONEY-COMB
_Teacher’s Story_
[Illustration: T]
The structure of honey-comb has been for ages admired by
mathematicians, who have measured the angles of the cells and
demonstrated the accurate manner in which the rhomb-shaped cell
changes at its base to a three faced pyramid; and proven that,
considering the material of construction, honey-comb exemplifies
the strongest and most economic structure possible for the storing
of liquid contents. While recent instruments of greater precision
in measuring angles, show less perfection in honey-comb than the
ancients believed, yet the fact still stands that the general plan of
it is mathematically excellent.
Some have tried to detract from bee skill, by stating that the
six-sided cell is simply the result of crowding cells together.
Perhaps this was the remote origin of the hexagonal cell; but if we
watch a bee build her comb, we find that she begins with a base laid
out in triangular pyramids, on either side of which she builds out
six-sided cells. A cell just begun, is as distinctly six-sided as
when completed.
[Illustration: _A section of honey. Note the caps to the cells, each
supported by six girders._]
The shape of the cell of a honey-comb is six-sided in cross section.
The bottom is a three-sided pyramid and its sides help form pyramids
at the bottom of the cells opposite, thus economizing every particle
of space. In the hive, the cells lie horizontal usually, although
sometimes the combs are twisted. The honey is retained in the cell
by a cap of wax which is made in a very cunning fashion; it consists
of a circular disc at the middle supported from the six angles of
the cell by six tiny girders. The comb is made fast to the section
of the hive by being plastered upon it. The foundation comb sold
to apiarists is quite thick, so that the edges of the cell may be
drawn out and almost complete the sides of the cell. However, the
foundation comb is expensive and is ordinarily used by the bee-keeper
simply as a starter, which means a little strip a few inches or so in
width fastened to the top of a section just to give the bees a hint
that this is the direction in which the comb should be built, a hint
which the bees invariably take. The cells of honey-comb are used
also for the storing of bee-bread and also as cradles for the young
bees.
_References_--The Bee People, Morley; How to Keep Bees, Comstock.
[Illustration: _Starters of foundation comb in section boxes,
partially built out by the bees. The section at the left has a
“starter” of foundation comb. The other sections show the work of the
bees in drawing out and building on the “starters.”_]
LESSON CIV
THE HONEY-COMB
_Leading thought_--The cells of honey-comb are six-sided and in
double rows and are very perfectly arranged for the storing of honey,
so as to save room.
_Materials_--A section filled with honey and also a bit of empty comb
and a bit of commercial foundation comb which may be obtained in any
apiary.
_Observations_--1. Look at a bit of empty honey-comb; what is the
shape of the cell as you look down into it?
2. What is the shape of the bottom of the cell?
3. How does the bottom of the cell join the bottom of the cell
opposite? Explain how honey-comb economizes space as storage for
honey, and why an economy of space is of use to bees in the wild
state.
4. In the hive is the honey-comb placed so that the length of the
cells are horizontal or up and down?
5. Observe honey-comb containing honey; how is the honey retained in
the cells?
6. Carefully take off a cap from the honey cell and see if you can
find the six girders that extend inward from the angles of the cell
to support the circular portion in the center.
7. By what means is the honey-comb made fast to the sides of the
section or the hive?
8. Study a bit of foundation comb and note where the bees will pull
out the wax to form the cell.
9. Why and how is foundation comb used by the bee-keeper?
10. For what purpose besides storing honey are the cells of
honey-comb used by the bees?
INDUSTRIES OF THE HIVE AND THE OBSERVATION HIVE
_Teacher’s Story_
[Illustration: B]
Bee-hives are the houses which man furnishes for the bee colonies,
the wild bees ordinarily living in hollow trees or in caves. The
usual hive consists of a box which is the lower story and of one or
more upper stories, called “supers.” In the lower story are placed
frames for the brood and for storing the honey for the winter use
of the bees. In the supers are placed the sections, each of which
is planned to hold a pound of honey. It is the habit of the bees to
place their brood in the lower part of their nests and store honey
in the upper portions. The bee-keepers have taken advantage of this
habit of the bees and remove the supers with their filled sections
and replace them with others to be filled, and thus get a large crop
of honey. The number of bees in a colony varies; there should be at
least 40,000 in a healthy colony. Of these a large proportion are
workers; there may be a few hundred drones the latter part of the
season but only one queen.
Honey-comb is built of wax and is hung from the frame so that the
cells are horizontal; its purpose is to cradle the young and for the
storage of pollen and honey. The wax used for building the comb is a
secretion of the bees; when comb is needed, a number of self-elected
bee citizens gorge themselves with honey and hang themselves up in
a curtain, each bee reaching up with her fore feet and taking hold
of the hind feet of the one above her. After remaining thus for
some time the wax appears in little plates, one on each side of the
second, third, fourth and fifth segments of the abdomen. This wax is
chewed by the bees and made into comb.
[Illustration: _A home-made observation hive._]
Honey is made from the nectar of flowers which the bee takes into
her honey stomach. This, by the way, is not the true stomach of the
bee and has nothing to do with digestion. It is simply a receptacle
for storing the nectar, which is mixed with some secretion from the
glands of the bee which brings about chemical changes, the chief
of which is changing the cane sugar of the nectar into the more
easily digested grape sugar of the honey. After the honey is emptied
from the honey stomach into the cell, it remains exposed to the air
for some time before the cell is capped, and thus ripens. It is an
interesting fact that up to the seventeenth century honey was the
only means people had for sweetening their food, as sugar was unknown.
Bee-bread is made from the pollen of flowers which is perhaps mixed
with saliva so as to hold together; it is carried from the field on
the pollen baskets of the hind legs of the workers; it is packed into
the cell by the bees and is used for food. Propolis is bee glue; it
is used as a cement and varnish; it is gathered by the bees from the
leaf-buds of certain trees and plants, although when they can get
it, the bees will take fresh varnish. It is used as a filler to make
smooth the rough places of the hive; it often helps hold the combs in
place; it calks every crack; it is applied as a varnish to the cells
of the honey-comb if they remain unused for a time, and if the door
of the observation hive be left open the bees will cover the inside
of the glass with this glue, and thus make the interior of the hive
dark.
The young bees are footless, white grubs. Each one lives in its
own little cell and is fed by the nurse bees, which give it partly
digested food from their own stomachs.
The removal of honey from the supers does not do any harm to the
bee colony if there is enough honey left in the brood chambers to
support the bees during the winter. There should be twenty-five or
thirty pounds of honey left in the brood chamber for winter use. In
winter, the hives should be protected from the cold by being placed
in special houses or by being encased in larger boxes, leaving an
opening so that the bees may come out in good weather. The chaff hive
is best for both winter and summer, as it surrounds the hive with a
space, which is filled with chaff, and keeps the hive warm in winter
and cool in summer. Many bee-keepers put their bees in cellars during
the winter, but this method is not as safe as the chaff hive. Care
should be taken in summer to place the hives so that they are shaded
at least part of the day. The grass should be mown around the hives
so that the bees will not become entangled in it as they return from
the fields laden with honey.
_What may be seen in the observation hive_--First of all, it is very
interesting to watch the bees build their comb. When more comb is
needed certain members of the colony gorge themselves with honey and
remain suspended while it oozes out of the wax pockets on the lower
side of the abdomen. This wax is collected and chewed to make it less
brittle and then is carried to the place where the comb is being
built and is molded into shape by the jaws of the workers. However,
the bee that puts the wax in place is not always the one that molds
it into comb.
A bee comes into the hive with her honey stomach filled with nectar
and disgorges this into a cell. When a bee comes in loaded with
pollen, she first brushes it from the pollen baskets on her hind legs
into the cell; later another worker comes along and packs the pollen
grains into the cell with her head, which is a comical sight.
The bee nurses run about on the comb feeding the young bee grubs
partially digested honey and pollen regurgitated from their own
stomachs. Whenever the queen moves about the comb she is followed
by a retinue of devoted attendants which feed her on the rich and
perfectly digested royal jelly and also take care of her royal
person and give her every attention possible. The queen, when laying,
thrusts her abdomen into the cell and glues a little white egg to the
bottom. The specially interesting thing about this is that the queen
always lays an egg which will produce a female, or worker in the
smaller cells and will always lay an egg to produce a drone or male
in the larger cells.
[Illustration: _The observation hive made and sold by A. I. Root._]
If there is any foreign substance in the observation hive it is
interesting to see the bees go to work at once to remove it. They
dump all of the debris out in front of the hive. They close all
crevices in the hive; and they will always curtain the glass, if
the door is kept open too much, with propolis or bee glue, which
is a very sticky substance which they get from leaf buds and other
vegetable sources. When bees fan to set up a current of air in the
hive, they glide back and forth, moving the wings so rapidly that we
can only see a blur about their bodies.
If drones are developed in the hive, it is interesting to see how
tenderly they are fed by their sister workers, although they do not
hesitate to help themselves to the honey stored in the cells; and if
the observation hive is working during September, undoubtedly the
pupils may be able to see the murder of the drones by their sisters.
But the children should understand that this killing of the drones is
necessary for the preservation of the colony, as the workers cannot
store enough honey to keep the colony alive during the winter if the
drones were allowed to go on feeding.
If you see the worker bees fighting, it means that robbers are
attempting to get at the stores of the observation hive. The entrance
to the hive should at once be contracted by placing a block of wood
in front, so that there is room for only one bee at a time to pass in
and out.
LESSON CV
THE INDUSTRIES OF THE HIVE
_Leading thought_--In the hive are carried on the industries of
wax-making, building of honey-comb, storing of honey and bee-bread,
caring for the young, keeping the hive clean and ventilated and
calking all crevices with bee glue.
_Method_--This lesson should be in the nature of a demonstration. If
there is an apiary in the neighborhood, it is quite possible that the
teacher may show the pupils a hive ready for occupancy by the bees;
in any case she will have no difficulty in borrowing a frame of brood
comb, and this with a section of honey which can be bought at the
grocery store, is sufficient if there is no observation hive. This
lesson should be an informal talk between teacher and pupils.
An observation hive in the schoolroom is an object of greatest
interest to the pupils, as through its glass sides they may be able
to verify for themselves the wonderful tales concerning the lives and
doings of the bees which have been told us by naturalists. Moreover,
the study thus made of the habits of the bees is an excellent
preparation for the practical apiarist, and we sincerely believe that
bee-keeping is one of the ways by which the boys and girls of the
farm may obtain money for their own use.
The observation hive is very simply constructed and can be made by
anyone who knows how to use ordinary carpenter tools. It is simply
a small, ordinary hive with a pane of glass on each side which is
covered by a hinged door. A hive thus made is placed so that the
front end rests upon a window sill; the sash is lifted an inch or so,
a strip of wood, or a piece of wire netting being inserted underneath
the sash except in front of the entrance of the hive, to hinder the
bees from coming back into the room. A covered passageway should
extend from the entrance of the hive to the outside of the window
sill. This window should be one which opens away from the playground
so that the bees coming and going, will not come into collision with
the pupils. The observation window should be kept carefully shut,
except when the pupils are using it, since the bees object to light
in their homes.
The A. I. Root Co., of Medina, Ohio, sell a pretty observation hive
which we have used successfully by stocking it afresh each season,
it being too small for a self-sustaining colony. But it has the
advantage of smallness which enables us to see all that is going on
within it, which would be impossible in a larger hive. This hive
comes in several sizes, and will be shipped from the makers stocked
with bees at prices ranging from $1.25 to $4.00.
_Observations--Industries and care of the hive_--1. What is the hive,
and what do wild bees use instead of the hive? Describe as follows:
2. Describe a brood chamber and a super and the uses of each.
3. How many and what bees live in a hive.
4. How the honey-comb is made and placed and the purpose of it.
5. How the wax is produced and built into the comb.
6. How honey is made.
7. What bee-bread is and its uses.
8. What propolis is and what it is used for.
9. How young bees look and how they are cradled and fed.
10. Does the removal of the honey from the supers in the fall do any
harm to the bee colony?
11. How much honey should a good-sized colony have in the fall to
winter well?
12. How should the hives be protected in the winter and summer?
_What may be seen in the observation hive_--13. Describe how a bee
works when building honey-comb.
14. How does the bee act when storing honey in a cell?
15. How does a bee place pollen in a cell and pack it into bee-bread?
16. Describe how the nurse bees feed the young, and how the young
look when eating.
17. Describe how the “ladies in waiting” feed and care for the queen.
18. Try to observe the queen when she is laying eggs and describe her
actions.
19. How do the bee workers keep their house clean?
20. How do they stop all crevices in the hive? If you keep the hive
uncovered too long, how will they curtain the window?
21. Describe the actions of the bees when they are ventilating the
hive.
22. If there are any drones in the hive, describe how they are fed.
23. How can you tell queens, drones and workers apart?
[Illustration: _A wasp’s nest with side walls removed._]
VII. OTHER INVERTEBRATE-ANIMAL STUDY
THE GARDEN SNAIL
_Teacher’s Story_
[Illustration: P]
Perchance if those who speak so glibly of a “snail’s pace” should
study it, they would not sneer at it, for carefully observed, it
seems the most wonderful method of locomotion ever devised by animal.
Naturally enough, the snail cannot gallop since it has but one foot;
but it is safe to assert that this foot, which is the entire lower
side of the body, is a remarkable organ of locomotion. Let a snail
crawl up the side of a tumbler and note how this foot stretches
out and holds on. It has flanges along the sides, which secrete
an adhesive substance that enables the snail to cling, and yet it
also has the power of letting go at will. The slow, even, pushing
forward, of the whole body, weighted by the unbalanced shell, is as
mysterious and seemingly as inevitable, as the march of fate, so
little is the motion connected with any apparent muscular effort. But
when his snailship wishes to let go and retire from the world, this
foot performs a feat which is certainly worthy of a juggler; it folds
itself lengthwise, and the end on which the head is retires first
into the shell, the tail end of the foot being the last to disappear.
And now find your snail!
Never was an animal so capable of stretching out and then folding
up all its organs, as is this little tramp who carries his house
with him. Turn one on his back when he has withdrawn into his little
hermitage, and watch what happens. Soon he concludes he will find
out where he is, and why he is bottomside up; as the first evidence
of this, the hind end of the foot, which was folded together, pushes
forth; then the head and horns come bubbling out. The horns are not
horns at all, but each is a stalk bearing an eye on the tip. This is
arranged conveniently, like a marble fastened to the tip of a glove
finger. When a snail wishes to see, it stretches forth the stalk as
if it were made of rubber; but if danger is perceived, the eye is
pulled back exactly as if the marble were pulled back through the
middle of the glove finger; or as a boy would say, “it goes into the
hole and pulls the hole in after it.” Just below the stalked eyes, is
another pair of shorter horns, which are feelers, and which may be
drawn back in the same manner; they are used constantly for testing
the nature of the surface on which the snail is crawling. It is an
interesting experiment to see how near to the eyes and the feelers
we can place an object, before driving them back in. With these two
pairs of sense organs pushed out in front of him, the snail is well
equipped to observe the topography of his immediate vicinity; if he
wishes to explore above, he can stand on the tip of his tail and
reach far up; and if there is anything to take hold of, he can glue
his toe fast to it and pull himself up. Moreover, I am convinced that
snails have decided views about where they wish to go, for I have
tried by the hour to keep them marching lengthwise on the piazza
railing, so as to study them; and every snail was determined to go
crosswise and crawl under the edge, where it was nice and dark.
It is interesting to observe through a lens, the way a snail takes
his dinner; place before him a piece of sweet apple or other soft
fruit, and he will lift himself on his front toe and begin to work
his way into the fruit. He has an efficient set of upper teeth, which
look like a saw and are colored as if he chewed tobacco; with these
teeth and with his round tongue, which we can see popping out, he
soon makes an appreciable hole in the pulp; but his table manners are
not nice, since he is a hopeless slobberer.
[Illustration: _Snail sketches._
1. The thorny path to bliss; 2. Snail showing the breathing-pore; 3.
Prospecting.]
There are right and left spiraled snails. All those observed for
this lesson show the spiral wound about the center from left over
to right, or in the direction of the movement of the hands of a
clock, and this is usually the case. With the spiral like this, the
breathing pore is on the right side of the snail and may be seen as
an opening where the snail joins the shell. This pore may be seen to
open and contract slowly; by this motion, the air is sucked into the
shell where it bathes the snail’s lung, and is then forced out--a
process very similar to our own breathing.
The snail has good judgment when attacked; at the first scare, he
simply draws in his eyes and feelers and withdraws his head, so that
nothing can be seen of him from above, except a hard shell which
would not attract the passing bird. But if the attack continues, he
lets go all hold on the world, and nothing can be seen of him but a
little mass which blocks the door to his house; and if he is obliged
to experience a drought, he makes a pane of glass out of mucus across
his door, and thus stops evaporation. This is a very wise precaution,
because the snail is made up largely of moisture and much water is
needed to keep his mucilage factory running.
The way the snail uses his eyes is comical; he goes to the edge
of a leaf and pokes one eye over to see what the new territory is
like; but if his eye strikes an object, he pulls that one back, and
prospects for a time with the other. He can lengthen the eye-stalk
amazingly if he has need. How convenient for us if we could thus see
around a corner. If a small boy were as well off as a snail, he could
see the entire ball game through a knot-hole in the fence. In fact,
the more we study the snail, the more we admire, first his powers
of ascertaining what there is in the world, and then his power of
getting around in the world by climbing recklessly and relentlessly
over obstacles, not caring whether he is right side up on the floor
or hanging wrong side up from the ceiling; and, finally, we admire
his utter reticence when things do not go to suit him. I think
the reason I always call a snail “he” is because he seems such a
philosopher--a Diogenes in his tub. However, since the snail combines
both sexes in one individual the pronoun is surely applicable.
When observed through a lens, the snail’s skin looks like that of the
alligator, rough and divided into plates, with a surface like pebbled
leather; and no insect intruder can crawl up his foot and get into
the shell “unbeknownst,” for the shell is grown fast to the flange,
that grows out of the middle of the snail’s back. The smoother the
surface the snail is crawling upon, the harder to make him let go.
The reason for this lies in the mucus, which he secretes as he goes,
and which enables him to fasten himself anywhere; he can crawl up
walls or beneath any horizontal surface, shell downward, and he
leaves a shining trail behind him wherever he goes.
Snail eggs are as large as small peas, almost transparent, covered
with very soft shells, and fastened together by mucus. They are laid
under stones and decaying leaves. As soon as the baby snail hatches,
it has a shell with only one spiral turn in it; as it grows, it adds
layer after layer to the shell on the rim about the opening--which
is called the lip; these layers we can see as ridges on the shell.
If we open an empty shell, we can see the progress of growth in the
size of the spirals. Snails eat succulent leaves and other soft
vegetable matter. During the winter, they bury themselves beneath
objects or retire into soft humus. In preparing for the winter, the
snail makes a door of mucus and lime, or sometimes three doors, one
behind another, across the entrance to his shell, leaving a tiny hole
to admit the air. There are varieties of snails which are eaten as
dainties in Europe, and are grown on snail farms for the markets. The
species most commonly used is the same as that which was regarded as
a table luxury by the ancient Romans.
_References_--Wild Life, Ingersoll; The Natural History of Some
Common Animals, Latter.
LESSON CVI
THE GARDEN SNAIL
_Leading thought_--The snail carries his dwelling with him, and
retires within it in time of danger. He can climb on any smooth
surface.
_Method_--The pupils should make a snailery, which may consist of any
glass jar, with a little soil and some moss or leaves at the bottom,
and a shallow dish of water at one side. The moss and soil should be
kept moist. Place the snails in this and give them fresh leaves or
pulpy fruit, and they will live comfortably in confinement. A bit of
cheese-cloth fastened with a rubber band should be placed over the
top of the jar. A tumbler inverted over a dish, on which is a leaf or
two, makes a good observation cage to pass around the room for closer
examination. An empty shell should be at hand, which may be opened
and examined.
_Observations_--1. Where do you find snails? Why do they like to live
in such places?
2. How does a snail walk? Describe its “foot.” How can it move with
only one foot? Describe how it climbs the side of the glass jar. How
does it cling?
3. What sort of a track does a snail leave behind it? What is the use
of this mucus?
4. Where are the snail’s eyes? Why is this arrangement convenient? If
we touch one of the eyes what happens? What advantage is this to the
snail? Can it pull in one eye and leave the other out?
5. Look below the eyes for a pair of feelers. What happens to these
if you touch them?
6. What is the use of its shell to a snail? What does the snail do if
startled? If attacked? When a snail is withdrawn into its shell can
you see any part of the body? Is the shell attached to the middle of
the foot? How did the shell grow on the snail’s back? How many spiral
turns are there in the full-grown shell? Are there as many in the
shell of a young snail? Can you see the little ridges on the shell?
Do you think that these show the way the shell grew?
7. Can you find the opening through which the snail draws its breath?
Where is this opening? Describe its action.
8. Put the snail in a dry place for two or three days, and see what
happens. Do you think this is for the purpose of keeping in moisture?
What does the snail do during the winter?
9. Place a snail on its back and see how it rights itself. Describe
the way it eats. Can you see the horny upper jaw? Can you see the
rasping tongue? What do snails live on?
10. Do you know how the snail eggs look and where they are laid? How
large is the shell of the smallest garden snail you ever saw? How
many spiral turns were there in it? Open an empty snail shell and see
how the spirals widened as the snail grew. Do you think the shell
grew by layers added to the lip?
11. Do all snails have shells? Describe all the kinds of snails you
know. What people consider snails a table delicacy?
_TO A SNAIL_
_Little Diogenes bearing your tub, whither away so gay,
With your eyes on stalks, and a foot that walks, tell me this
I pray!
Is it an honest snail you seek that makes you go so slow,
And over the edges of all things peek? Have you found him, I
want to know;
Or do you go slow because you knew, your house is near and
tight?
And there is no hurry and surely no worry lest you stay out
late at night._
THE EARTHWORM
_Teacher’s Story_
[Illustration: A]
Although not generally considered attractive, for two reasons the
earthworm has an important place in nature-study: it furnishes an
interesting example of lowly organized creatures, and it is of
great economic importance to the agriculturist. The lesson should
have special reference to the _work_ done by earthworms and to the
simplicity of the tools with which the work is done.
The earthworm is, among lower animals, essentially the farmer. Long
before man conceived the idea of tilling the soil, this seemingly
insignificant creature was busily at work plowing, harrowing, and
fertilizing the land. Nor did it overlook the importance of drainage
and the addition of amendments--factors of comparatively recent
development in the management of the soil by man.
Down into the depths, sometimes as far as seven or eight feet, but
usually from twelve to eighteen inches, goes the little plowman,
bringing to the surface the subsoil, which is exactly what we do when
we plow deeply. To break up the soil as our harrows do, the earthworm
grinds it in a gizzard stocked with grains of sand or fine gravel,
which act as millstones. Thus it turns out soil of much finer texture
than we, by harrowing or raking, can produce. In its stomach it adds
the lime amendment, so much used by the modern farmer. The earthworm
is apparently an adept in the use of fertilizers; it even shows
discrimination in keeping the organic matter near the surface, where
it may be incorporated into the soil of the root zone. It drags into
its burrows dead leaves, flowers and grasses, with which to line the
upper part. Bones of dead animals, shells, and twigs are buried by
it, and, being more or less decayed, furnish food for plants. These
minute agriculturists have never studied any system of drainage, but
they bore holes to some depth which carry off the surplus water. They
plant seeds by covering those that lie on the ground with soil from
below the surface--good, enriched, well granulated soil it is, too.
They further care for the growing plants by cultivating, that is
keeping fine and granular, the soil about the roots.
It was estimated by Darwin that, in garden soil in England, there
are more than 50,000 earthworms in an acre, and that the whole
superficial layer of vegetable mold passes through their bodies in
the course of every few years, at the rate of eighteen tons per acre
yearly.
This agricultural work of the earthworm has been going on for ages.
Wild land owes much of its beauty to this diminutive creature which
keeps the soil in good condition. The earthworm has undermined and
buried rocks, changing greatly the aspect of the landscape. It has
preserved ruins and ancient works of art. Several Roman villas in
England owe their preservation to the earthworm. All this work is
accomplished with the most primitive tools, a tiny proboscis, a
distensible pharynx, a rather indeterminate tail, a gizzard and the
calcareous glands peculiar to this lowly creature.
An earthworm has a peculiar, crawling movement. Unlike the snake,
which also moves without legs, it has no scales to function in part
as legs; but it has a very special provision for locomotion. On the
under side of a worm are found numerous _setæ_--tiny, bristlelike
projections. These will be seen to be in double rows on each segment,
excepting the first three and the last. The setæ turn so that they
point in the opposite direction from which the worm is moving. It is
this use of these clinging bristles, together with strong muscles,
which enables a worm to hold tightly to its burrow when bird or man
attempts its removal. A piece of round elastic furnishes an excellent
example of contraction and extension, such as the earthworm exhibits.
Under the skin of the worm are two sets of muscles; the outer passing
in circular direction around the body, the inner running lengthwise.
The movement of these may be easily seen in a good-sized, living
specimen. The body is lengthened by the contraction of circular and
the extension of longitudinal muscles, and shortened by the opposite
movement.
The number of segments may vary with the age of the worm. In the
immature, the _clitellum_, a thick, whitish ring near the end,
is absent. The laying of the earthworm’s egg is an interesting
performance. A sac-like ring is formed about the body in the region
of the clitellum. This girdle is gradually worked forward and, as it
is cast over the head, the sac-ends snap together enclosing the eggs.
These capsules, yellowish-brown, football-shaped, about the size of
a grain of wheat, may be found in May or June about manure piles or
under stones.
Earthworms are completely deaf, although sensitive to vibration.
They have no eyes, but can distinguish between light and darkness.
The power of smell is feeble. The sense of taste is well developed;
the sense of touch is very acute; and we are not so sure as is Dr.
Jordan, that the angleworm is at ease on the hook.
Any garden furnishes good examples of the home of the earthworm. The
burrows are made straight down at first, then wind about irregularly.
Usually they are about one or two feet deep, but may reach even eight
feet. The burrow terminates generally in an enlargement where one
or several worms pass the winter. Toward the surface, the burrow is
lined with a thin layer of fine, dark colored earth, voided by the
worm. This creature is an excavator and builder of no mean ability.
The towerlike “castings” so characteristic of the earthworm, are
formed with excreted earth. Using the tail as a trowel, it places
earth, now on one side and now on the other. In this work, of course,
the tail protrudes; in the search for food, the head is out. A worm,
then, must make its home, narrow as it is, with a view to being able
to turn in it.
An earthworm will bury itself in loose earth in two or three minutes,
and in compact soil, in fifteen minutes. Pupils should be able to
make these observations easily either in the terrarium or in the
garden.
In plugging the mouths of their burrows, earthworms show something
that seems like intelligence. Triangular leaves are invariably
drawn in by the apex, pine-needles by the common base, the manner
varying with the shape of the leaf. They do not drag in a leaf by the
footstalk, unless its basal part is as narrow as the apex. The mouth
of the burrow may be lined with leaves for several inches.
The burrows are not found in dry ground nor in loose sand. The
earthworm lives in the finer, moderately wet soils. It must have
moisture since it breathes through the skin, and it has sufficient
knowledge of soil texture and plasticity to recognize the futility of
attempts at burrow building with unmanageable, large grains of sand.
These creatures are nocturnal, rarely appearing by day unless
“drowned out” of the burrows. During the day they lie near the
surface extended at full length, the head uppermost. Here they
are discovered by keen-eyed birds and sacrificed by thousands,
notwithstanding the strong muscular protest of which they are capable.
Seemingly conscious of its inability to find the way back to its
home, an earthworm anchors tight by its tail while stretching
its elastic length in a foraging expedition. It is an omnivorous
creature, including in its diet earth, leaves, flowers, raw meat,
fat, and even showing cannibalistic designs on fellow earthworms.
In the schoolroom, earthworms may be fed on pieces of lettuce or
cabbage leaves. A feeding worm will show the proboscis, an extension
of the upper lip used to push food into the mouth. The earthworm has
no hard jaws or teeth, yet it eats through the hardest soil. Inside
the mouth opening is a very muscular pharynx, which can be extended
or withdrawn. Applied to the surface of any small object it acts as
a suction pump, drawing food into the food tube. The earth taken
in furnishes some organic matter for food; calcareous matter is
added to the remainder before being voided. This process is unique
among animals. The calcareous matter is supposed to be derived from
leaves which the worms eat. Generally the earth is swallowed at some
distance below the surface, and finally ejected in characteristic
“castings.” Thus, the soil is slowly worked over and kept in good
condition by earthworms, of which Darwin says: “It may be doubted
whether there are many other animals which have played so important
a part in the history of the world as have these lowly organized
creatures.”
_References_--The Earthworm, Darwin; The Natural History of Some
Common Animals, Latter.
* * * * *
“_Fly fishing is an art, a fine art beyond a doubt, but it is
an art and, like all art, it is artificial. Fishing with an
angleworm is natural. It fits into the need of the occasion.
It fits in with the spirit of the boy. It is not by chance
that the angleworm, earthworm, fishworm, is found in every
damp bank, in every handy bit of sod, the green earth over,
where there are races whose boys are real boys with energy
enough to catch a fish. It is not by chance that the angleworm
makes a perfect fit on a hook, with no anatomy with which to
feel pains, and no arms or legs to be broken off or to be
waved helplessly in the air. Its skin is tough enough so as
not to tear, not so tough as to receive unseemly bruises, when
the boy is placing it on the hook. The angleworm is perfectly
at home on the hook. It is not quite comfortable anywhere
else. It crawls about on sidewalks after rain, bleached and
emaciated. It is never quite at ease even in the ground, but
on the hook it rests peacefully, with the apparent feeling
that its natural mission is performed._”
--“BOYS’ FISH AND BOYS’ FISHING,” BY DAVID STARR JORDAN.
LESSON CVII
THE EARTHWORM
_Leading thought_--The earthworm is a creature of the soil and is of
much economic importance.
_Method_--Any garden furnishes abundant material for the study of
earthworms. They are nocturnal workers and may be observed by lantern
light. To form some estimate of the work done in a single night,
remove the “casts” from a square yard of earth one day, and examine
that piece of earth the next. It is well to have a terrarium in the
schoolroom for frequent observation. Scatter grass or dead leaves
on top of the soil, and note what happens. For the study of the
individual worm and its movements, each pupil should have a worm with
some earth upon his desk.
_Observations_--1. How does the earthworm crawl? How does it turn
over? Has it legs? Compare its movement with that of a snake, another
legless animal. What special provision for locomotion has the
earthworm?
2. Compare the lengths of the contracted and extended body. How
accounted for?
3. Describe the body--its shape and color, above and below. Examine
the segments. Do all the worms have the same number? Compare the head
end with the tail end of the body. Has every worm a “saddle,” or
clitellum?
4. Does the earthworm hear easily? Has it eyes? Is it sensible to
smell or to touch? What sense is most strongly developed?
5. Describe the home of the earthworm. Is it occupied by more than
one worm? How long does it take a worm to make a burrow? How does it
protect its home? How does it make a burrow? In what kind of soil do
you find earthworms at work?
6. Is the earthworm seen most often at night or by day? Where is it
the rest of the time? How does it hold to its burrow? When is the
tail end at the top? When the head end?
7. What is the food of the earthworm? How does it get its food?
8. Look for the eggs of the earthworm about manure piles or under
stones.
9. What are the enemies of the earthworm? Is it a friend or an enemy
to us? Why?
10. The earthworm is a good agriculturist. Why?
[Illustration: _Where the crayfish lurks._]
THE CRAYFISH
_Teacher’s Story_
[Illustration: W]
When I look at a crayfish I envy it, so rich is it in organs with
which to do all that it has to do. From the head to the tail, it is
crowded with a large assortment of executive appendages. In this day
of multiplicity of duties, if we poor human creatures only had the
crayfish’s capabilities, then might we hope to achieve what lies
before us.
The most striking thing in the appearance of the crayfish is the
great pair of nippers on each of the front legs. Wonderfully are its
“thumb and finger” put together; the “thumb” is jointed so that it
can move back and forth freely; and both are armed, along the inside
edge, with saw teeth and with a sharp claw at the tip so that they
can get a firm grip upon an object. Five segments in these great
legs can be easily seen; that joining the body is small, but each
successive one is wider and larger, to the great forceps at the end.
The two stout segments behind the nippers give strength, and also a
suppleness that enables the claws to be bent in any direction.
The legs of the pair behind the big nippers have five segments
readily visible; but these legs are slender and the nippers at the
end are small; the third pair of legs is armed like the second pair;
but the fourth and fifth pairs lack the pincers, and end in a single
claw.
But the tale of the crayfish’s legs is by no means told; for between
and above the great pincers is a pair of short, small legs tipped
with single claws, and fringed on their inner edges. These are the
maxillapeds, or jaw-feet; and behind them, but too close to be seen
easily, are two more pairs of jaw-feet. As all of these jaw-feet
assist at meals, the crayfish apparently always has a “three fork”
dinner; and as if to provide accommodations for so many eating
utensils, it has three pairs of jaws all working sidewise, one
behind the other. Two of these pairs are maxillæ and one, mandibles.
The mandibles are the only ones we see as we look in between the
jaw-feet; they are notched along the biting edge. Connected with
the maxillæ, on each side, are two pairs of threadlike flappers,
that wave back and forth vigorously and have to do with setting up
currents of water over the gills.
Thus we see that, in all, the crayfish has three pairs of jaw-feet,
one pair of great nippers and four pairs of walking feet, two of
which also have nippers and are used for digging and carrying.
When we look upon the crayfish from above, we see that the head
and thorax are fastened solidly together, making what is called a
cephalothorax. The cephalothorax is covered with a shell called
the carapace, which is the name given also to the upper part of
the turtle’s shell. The suture where the head joins the thorax is
quite evident. In looking at the head, the eyes first attract our
attention; each is black and oval and placed on the tip of a stalk,
so it can be extended or retracted or pushed in any direction, to
look for danger. These eyes are like the compound eyes of insects, in
that they are made up of many small eyes, set together in a honeycomb
pattern.
The long antennæ are as flexible as braided whiplashes, large at
the base and ending in a threadlike tip. They are composed of many
segments, the basal ones being quite large. Above the antennæ on
each side, is a pair of shorter ones called antennules, which come
from the same basal segment; the lower one is the more slender
and is usually directed forward; the upper one is stouter, curves
upward, and is kept always moving, as if it were constantly on the
alert for impressions. The antennæ are used for exploring far ahead
or behind the creature, and are often thrust down into the mud and
gravel at the bottom of the aquarium, as if probing for treasure. The
antennules seem to give warning of things closer at hand. Between
the antennæ and antennules is a pair of finger-like organs, that
are hinged at the outer ends and can be lifted back, if we do it
carefully.
In looking down upon a crayfish, we can see six abdominal
segments and the flaring tail at the end, which is really another
segment greatly modified. The first segment, or that next to the
cephalothorax, is narrow; the others are about equal in size, each
graceful in shape, with a widened part at each side which extends
down along the sides of the creature. These segments are well hinged
together so that the abdomen may be completely curled beneath the
cephalothorax. The plates along the sides are edged with fringe.
The tail consists of five parts, one semicircular in the center,
and two fan-shaped pieces at each side, and all are margined with
fringe. This tail is a remarkable organ. It can be closed or extended
sidewise like a fan; it can be lifted up or curled beneath.
Looking at the crayfish from below, we see on the abdomen some very
beautiful featherlike organs called swimmerets. Each swimmeret
consists of a basal segment with twin paddles joined to its tip,
each paddle being narrow and long and fringed with hairs. The mother
crayfish has four pairs of these, one pair on each of the second,
third, fourth and fifth segments; her mate has an additional larger
pair on the first segment. These swimmerets, when at rest, lie close
to the abdomen and are directed forward and slightly inward. When in
motion, they paddle with a backward, rhythmic motion, the first pair
setting the stroke and the other pairs following in succession. This
motion sends the body forward, and the swimmerets are chiefly used
to aid the legs in forward locomotion. A crayfish, on the bottom of
a pond, seems to glide about with great ease; but place it on land,
and it is an awkward walker. The reason for this difference lies, I
believe, in the aid given by the swimmerets when the creature is in
water. Latter says: “In walking, the first three pairs of legs pull
and the fourth pair pushes. Their order of movement is as follows:
The first on the right and the third on the left side move together,
next the third right and the first left, then the second right and
fourth left, and lastly the fourth right and second left.”
When the crayfish really wishes to swim, the tail is suddenly brought
into use; it is thrust out backward, lays hold of the water by
spreading out widely, and then doubles under with a spasmodic jerk
which pulls the creature swiftly backward.
The crayfish’s appearance is magically transformed when it begins to
swim; it is no longer a creature of sprawling awkward legs and great
clumsy nippers; now, its many legs lie side by side supinely and the
great claws are limp and flow along in graceful lines after the body,
all obedient to the force which sends the creature flying through the
water. I cannot discover that the swimmerets help in this movement.
[Illustration: _A crayfish._
Drawn by Anna C. Stryke.]
The mother crayfish has another use for her swimmerets; in the
spring, when she is ready to lay eggs, she cleans off her paddles
with her hind legs, covers them with waterproof glue, and then
plasters her eggs on them in grapelike clusters of little dark
globules. What a nice way to look after her family! The little ones
hatch, but remain clinging to the maternal swimmerets, until they are
large enough to scuttle around on the brook bottom and look out for
themselves.
The breathing apparatus of the crayfish cannot be seen without
dissection. All the walking legs, except the last pair, have gills
attached to that portion of them which joins the body, and which lies
hidden underneath the sides of the carapace or shell. The blood is
forced into these gills, sends off its impurities through their thin
walls and takes in the oxygen from the water, currents of which are
kept steadily flowing forward.
Crayfishes haunt still pools along brooksides and river margins
and the shallow ponds of our fresh waters. There they hide beneath
sticks and stones, or in caves of their own making, the doors of
which they guard with the big and threatening nippers, which stand
ready to grapple with anybody that comes to inquire if the folks
are at home. The upper surface of the crayfish’s body is always so
nearly the color of the brook bottom, that the eye seldom detects
the creature until it moves; and if some enemy surprises one, it
swims off with terrific jerks which roil all the water around and
thus covers its retreat. In the winter, our brook forms hibernate in
the muddy bottoms of their summer haunts. There are many species;
some in our Southern States, when the dry season comes on, live in
little wells which they dig deep enough to reach water. They heap up
the soil which they excavate around the mouth of the well, making
well-curbs of mud; these are ordinarily called “crawfish chimneys.”
The crayfishes find their food in the flotsam and jetsam of the pool.
They seem fond of the flesh of dead fishes and are often trapped by
its use as bait.
The growth of the crayfish is like that of insects; as its outer
covering is a hard skeleton that will not stretch, it is shed as
often as necessary; it breaks open down the middle of the back of
the carapace, and the soft bodied creature pulls itself out, even
to the last one of its claws. While its new skin is yet elastic, it
stretches to its utmost; but this skin also hardens after a time and
is, in its turn, shed. Woe to the crayfish caught in this helpless,
soft condition after molting! For it then has no way to protect
itself. We sometimes find the old skin floating, perfect in every
detail, and so transparent that it seems the ghost of a crayfish.
Not only is the crayfish armed in the beginning with a great number
of legs, antennæ, etc., but if it happens to lose any of these
organs, they will grow again. It is said that, when attacked, it can
voluntarily throw off one or more of its legs. We have often found
one of these creatures with one of the front claws much larger than
the other; it had probably lost its big claw in a fight, and the new
growth was not yet completed.
I have been greatly entertained by watching a female crayfish make
her nest in my aquarium which has, for her comfort, a bottom of three
inches of clean gravel. She always commences at one side by thrusting
down her antennæ and nippers between the glass and stones; she seizes
a pebble in each claw and pulls it up and in this way starts her
excavation; but when she gets ready to carry off her load, she comes
to the task with her tail tucked under her body, as a lady tucks up
her skirts when she has something to do that requires freedom of
movement. Then with her great nippers and the two pairs of walking
feet, also armed with nippers, she loads up as much as she can carry
between her great claws and her breast. She keeps her load from
overflowing by holding it down with her first pair of jaw-feet, just
as I have seen a schoolboy use his chin, when carrying a too large
load of books; and she keeps the load from falling out by supporting
it from beneath with her first pair of walking legs. Thus, she
starts off with her “apron” full, walking on three pairs of feet,
until she gets to the dumping place; then she suddenly lets go and
at the same time her tail straightens out with a gesture which says
plainly, “There!” Sometimes when she gets a very large load, she uses
her second pair of walking legs to hold up the burden, and crawls
off successfully, if not with ease, on two pairs of legs,--a most
unnatural quadruped.
I had two crayfishes in a cage in an aquarium, and each made a nest
in the gravel at opposite ends of the cage, heaping up the debris
into a partition between them. I gave one an earthworm, which she
promptly seized with her nippers; she then took up a good sized
pebble in the nippers of her front pair of walking legs, glided
over to the other nest, spitefully threw down both worm and pebble
on top of her fellow prisoner, and then sped homeward. Her victim
responded to the act by rising up and expressing perfectly, in his
attitude and the gestures of his great claws, the most eloquent of
crayfish profanity. In watching crayfishes carry pebbles, I have been
astonished to see how constantly the larger pair of jaw-feet are used
to help pick up and carry the loads.
LESSON CVIII
THE CRAYFISH
_Leading thought_--The crayfish, or crawfish, as it is sometimes
called, has one pair of legs developed into great pincers for seizing
and tearing its food and for defending itself from enemies. It can
live in mud or water. It belongs to the same animal group as do the
insects, and it is a near cousin of the lobster.
_Method_--Place a crayfish in an aquarium (a battery jar or a
two-quart Mason jar) in the schoolroom, keeping it in clear water
until the pupils have studied its form. It will rise to explore the
sides of the aquarium at first, and thus show its mouth parts, legs
and swimmerets. Afterwards, place gravel and stone in the bottom of
the aquarium, so that it can hide itself in a little cavity which it
will make by carrying pebbles from one side. Wash the gravel well
before it is put in, so that the water will be unclouded and the
children can watch the process of excavation.
_Observations_--1. What is there peculiar about the crayfish which
makes it difficult to pick it up? Examine one of these great front
legs carefully and see how wonderfully it is made. How many parts are
there to it? Note how each succeeding part is larger from the body to
the claws. Note the tips which form the nippers or chelæ, as they are
called. How are they armed? How are the gripping edges formed to take
hold of an object? How wide can the nippers be opened, and how is
this done? Note the two segments behind the great claw and describe
how they help the work of the nippers.
2. Study the pair of legs behind the great claws or chelæ, and
compare the two pairs, segment by segment. How do they differ except
as to size? How do the nippers at the end compare with the big ones?
Look at the next pair of legs behind these; are they similar? How
do the two pairs of hind legs differ in shape from the two pairs in
front of them?
3. Look between the great front claws and see if you can find another
pair of small legs. Can you see anything more behind or above these
little legs?
4. When the crayfish lifts itself up against the side of the jar,
study its mouth. Can you see a pair of notched jaws that work
sidewise? Can you see two or three pairs of threadlike organs that
wave back and forth in and out the mouth?
5. How many legs, in all, has the crayfish? What are the short legs
near the mouth used for? What are the great nippers used for? How
many legs does the crayfish use when walking? In what order are they
moved? Is the hind pair used for pushing? What use does it make of
the pincers on the first and second pairs of walking legs?
6. Look at the crayfish from above; the head and the covering of the
thorax are soldered together into one piece. When this occurs, the
whole is called a cephalothorax; and the cover is called by the same
name as the upper shell of the turtle, the carapace. Can you see
where the head is joined to the thorax?
7. Look carefully at the eyes. Describe how they are set. Can they be
pushed out or pulled in? Can they be moved in all directions? Of what
advantage is this to the crayfish?
8. How many antennæ has the crayfish? Describe the long ones and
tell how they are used. Do the two short ones on each side come from
the same basal segment? These little ones are called the antennules.
Describe the antennules of each side and tell how they differ. Can
you see the little fingerlike organs which clasp above the antennæ
and below the antennules on each side of the head? Can these be moved?
9. Look at the crayfish from above. How many segments are there in
the abdomen? Note how graceful the shape of each segment. Note that
each has a fan-shaped piece down the side. Describe how the edges of
the segments along the sides are margined.
10. Of how many pieces is the tail made? Make a sketch of it. How are
the pieces bordered? Can the pieces shut and spread out sidewise? Is
the tail hinged so it can be lifted up against the back or curled
under the body?
11. Look underneath the abdomen and describe the little fringed
organs called the swimmerets. How many are there?
12. How does the crayfish swim? With what does it make the stroke?
Describe carefully this action of the tail. When it is swimming,
does it use its swimmerets? Why do not the many legs and big nippers
obstruct the progress of the crayfish, when it is swimming?
13. When does the crayfish use its swimmerets? Do they work so as to
push the body backward or forward? Do you know to what use the mother
crayfish puts her swimmerets?
14. Do you know how crayfishes breathe? Do you know what they eat and
where they find it?
15. Where do you find crayfishes? Where do they like to hide? Do
they go headfirst into their hiding place, or do they back in? Do
they stand ready to defend their retreat? When you look down into
the brook, are the crayfishes usually seen until they move? Why is
this? Where do the crayfishes pass the winter? Did you ever see the
crayfish burrows or mud chimnies?
16. If the crayfish loses one of its legs or antennæ, does it grow
out again? How does the crayfish grow?
17. Put a crayfish in an aquarium which has three inches of coarse
gravel on the bottom, and watch it make its den. How does it loosen
up a stone? With how many legs does it carry its burden of pebbles
when digging its cave? How does it use its jaw-feet, its nippers, and
its first and second pairs of walking legs in this work?
* * * * *
“_A rock-lined, wood-embosomed nook,
Dim cloister of the chanting brook!
A chamber within the channelled hills,
Where the cold crystal brims and spills,
By dark-browed caverns blackly flows,
Falls from the cleft like crumbling snows,
And purls and splashes, breathing round
A soft, suffusing mist of sound._”
--J. T. TROWBRIDGE.
DADDY-LONGLEGS, OR GRANDFATHER GREYBEARD
_Teacher’s Story_
[Illustration: I]
I wonder if there ever was a country child who has not grasped firmly
the leg of one of these little sprawling creatures and demanded:
“Grandfather Greybeard, tell me where the cows are or I’ll kill
you,” and Grandfather Greybeard, striving to get away, puts out one
of his long legs this way, and another that way, and points in so
many directions that he usually saves his life, since the cows must
be somewhere. It would be more interesting to the children and less
embarrassing to the “daddy” if they were taught to look more closely
at those slender, hairlike legs.
“Daddy’s” long legs are seven jointed. The first segment is seemingly
soldered fast to the lower side of his body, and is called the coxa.
The next segment is a mere knob, usually black and ornamental,
and is called the trochanter. Then comes the femur, a rather long
segment directed upward; next is a short swollen segment--the “knee
joint” or patella; next the tibia, which is also rather long. Then
comes the metatarsus and tarsus, which seemingly make one long
downward-directed segment, outcurving at the tips, on which the
“daddy” tip-toes along.
I have seen a “daddy” walk into a drop of water and his foot was
never wetted, so light was his touch on the water surface film. The
second pair of legs is the longest; the fourth pair next, and the
first pair usually the shortest. The legs of the second pair are
ordinarily used in exploring the surroundings. Notice that, when the
“daddy” is running, these two legs are spread wide apart and keep in
rapid motion; their tips, far more sensitive than any nerves of our
own, tell him the nature of his surroundings, by a touch so light
that we cannot feel it on the hand. We have more respect for one
of these hairlike legs, when we know it is capable of transmitting
intelligence from its tip.
[Illustration: _One of “daddy’s” long legs with segments named._]
The “daddy” is a good traveler and moves with remarkable rapidity.
And why not? If our legs were as long in comparison as his, they
would be about forty feet in length. When the “daddy” is running, the
body is always held a little distance above the ground; but when the
second pair of legs suggests to him that there may be something good
to eat in the neighborhood, he commences a peculiar teetering motion
of the body, apparently touching it to the ground at every step; as
the body is carried tilted with the head down, this movement enables
the creature to explore the surface below him with his palpi, which
he ordinarily carries bent beneath his face, with the ends curled up
under his “chin.” The palpi have four segments that are easily seen,
and although they are ordinarily carried bent up beneath the head,
they can be extended out quite a distance if “daddy” wishes to test a
substance. The end segment of the palpus is tipped with a single claw.
Beneath the palpi is a pair of jaws; these, in some species, extend
beyond the palpi. I have seen a daddy-longlegs hold food to his jaws
with his palpi and he seemed also to use them for stuffing it into
his mouth.
The body of the daddy-longlegs is a little oblong object, looking
more like a big grain of wheat than anything else, because in these
creatures the head, thorax and abdomen are all grown together
compactly. On top of the body, between the feeler-legs, is a little
black dot, and to the naked eye it would seem that if this were an
organ of sight the creature must be a Cyclops with only one eye. But
under the lens this is seen to be a raised knob and there is on each
side of it, a little shining black eye. We hardly see the use of two
eyes set so closely together, but probably the “daddy” does.
[Illustration: _Grandfather-greybeard._
Comstock’s Manual.]
The most entertaining thing which a “daddy” in captivity is likely
to do, is to clean his legs; he is very particular about his legs,
and he will grasp one close to the basal joint in his jaws and slowly
pull it through, meanwhile holding the leg up to the jaws with the
palpi, while he industriously nibbles it clean for the whole length
to the very toe. Owing to the likelihood of his losing one of his
legs, he has the power of growing a new one; so we often see a
“daddy” with one or more legs only half grown.
There are many species of daddy-longlegs in the United States,
and some of them do not have the characteristic long legs. In the
North, all except one species die at the approach of winter; but
not until after the female, which, by the way, ought to be called
“granny-longlegs,” has laid her eggs in the ground, or under some
protecting stone, or in some safe crevice of wood or bark. In the
spring the eggs hatch into tiny little creatures which look just like
the old daddy-longlegs, except for their size. They get their growth
like insects, by shedding their skins as fast as they outgrow them.
It is interesting to study one of these cast skins with a lens. There
it stands with a slit down its back, and with the skin of each leg
absolutely perfect to the tiny claw! Again we marvel at these legs
that seem so threadlike, and which have an outer covering that can be
shed. Some say that the daddy-longlegs live on small insects which
they straddle over and pounce down upon, and some say they feed upon
decaying matter and vegetable juices. This would be an interesting
line of investigation for pupils, since they might be able to give
many new facts about the food of these creatures. The “daddies” are
night prowlers, and like to hide in crevices by day, waiting for the
dark to hunt for their food. They have several common names. Besides
the two given they are called “harvestmen” and the French call them
“haymakers.” Both of these names were very probably given, because
the creatures appear in greater numbers at the time of haying and
harvesting.
LESSON CIX
THE DADDY-LONGLEGS
_Leading thought_--These long-legged creatures have one pair of legs
too many to allow them to be classed with the insects. They are more
nearly related to the spiders, who also have eight legs. They are
pretty creatures when examined closely, and they do many interesting
things.
_Method_--Put a grandfather greybeard in a breeding cage or under
a large tumbler, and let the pupils observe him at leisure. If you
place a few drops of sweetened water at one side of the cage, the
children will surely have an opportunity to see this amusing creature
clean his legs.
_Observations_--1. Where did you find the harvestman? What did it
do as soon as it was disturbed? How many names do you know for this
little creature?
2. A “daddy” with such long legs certainly ought to have them
studied. How many segments in each leg? How do the segments look? How
do the legs look where they are fastened to the body? Which is the
longest pair of legs? The next? The next? The shortest?
3. If you had such long stilts as he has, they would be about forty
feet long. Would you lift yourself that high in the air? Does the
“daddy” lift his body high or swing it near the ground? What shape
is the body? Can you see if there is a distinct head? Can you see a
black dot on top of the front end of the body? If you should see this
dot through a microscope it would prove to be two bright black eyes.
Why should the daddy’s eyes be on top?
4. Do you see a pair of organs that look like feelers at the front
end of the body? These are called palpi. How does he use his palpi?
Give him a little bruised or decaying fruit, and see him eat. Where
do you think his mouth is? Where does he keep his palpi when he is
not using them for eating?
5. Note what care he takes of his legs. How does he clean them? Which
does he clean the oftenest? Do you think the very long second pair of
legs is used as much for feeling as for walking? Put some object in
front of the “daddy” and see him explore it with his legs. How much
of the leg is used as a foot when the “daddy” stands or runs?
6. When running fast, how does the “daddy” carry his body? When
exploring how does he carry it? Do you ever find the “daddy” with his
body resting on the surface on which he is standing? When resting,
are all eight of his legs on the ground? Which are in the air? Is the
head end usually tilted up or down?
7. Do you see the daddy-longlegs early in the spring? When do you
find him most often? How do you suppose he passes the winter in our
climate? Have you ever seen a “daddy” with one leg much shorter than
the other? How could you explain this?
8. Try and discover what the daddy-longlegs eats, and where he finds
his food.
SPIDERS
_Teacher’s Story_
[Illustration: T]
The spiders are the civil engineers among the small inhabitants of
our fields and woods. They build strong suspension bridges, from
which they hang nets made with exquisite precision; and they build
aeroplanes and balloons, which are more efficient than any that we
have yet constructed; for although they are not exactly dirigible,
yet they carry the little balloonists where they wish to go, and
there are few fatal accidents. Moreover, the spiders are of much
economic importance, since they destroy countless millions of insects
every year, most of which are noxious--like flies, mosquitoes, bugs
and grasshoppers.
There is an impression abroad that all spiders are dangerous to
handle. This is a mistake; the bite of any of our common spiders is
not nearly so dangerous as the bite of a malaria-laden mosquito.
Although there is a little venom injected into the wound by the bite
of any spider, yet there is no species found in the Northern States
whose bite is sufficiently venomous to be feared.
There is no need for studying the anatomy of the spider closely in
nature-study. Our interest lies much more in the wonderful structures
made by the spiders, than in a detailed study of the little creatures
themselves.
COBWEBS
“_Here shy Arachne winds her endless thread,
And weaves her silken tapestry unseen,
Veiling the rough-hewn timbers overhead,
And looping gossamer festoons between._”
--ELIZABETH AKERS.
Our house spiders are indefatigable curtain-weavers. We never suspect
their presence, until suddenly their curtains appear before our eyes,
in the angles of the ceilings--invisible until laden with dust. The
cobwebs are made of crisscrossed lines, which are so placed as to
entangle any fly that comes near. The lines are stayed to the sides
of the wall and to each other quite firmly, and thus they are able
to hold a fly that touches them. The spider is likely to be in its
little den at the side of the web; this den may be in a crevice in
the corner or in a tunnel made of the silk. As soon as a fly becomes
entangled in the web the spider runs to it, seizes it in its jaws,
sucks its blood, and then throws away the shell, the wings and legs.
If a spider is frightened, it at first tries to hide and then may
drop by a thread to the floor. If we catch the little acrobat it will
usually “play possum” and we may examine it more closely through a
lens. We shall find it is quite different in form from an insect.
First to be noted, it has eight legs; but most important of all, it
has only two parts to the body. The head and thorax are consolidated
into one piece, which is called the cephalothorax. The abdomen has no
segments like that of the insects, and is joined to the cephalothorax
by a short, narrow stalk. At the front of the head is the mouth,
guarded by two mandibles, each ending in a sharp claw, at the tip
of which the poison gland opens. It is by thrusting these mandibles
into its prey that it kills its victims. On each side of the mandible
is a palpus, which in the males is of very strange shape. The eyes
are situated on the top of the head. There are usually four pairs of
these eyes, and each looks as beady and alert as if it were the only
one.
The spinning organs of the spider are situated near the tip of the
abdomen, while the spinning organ of the caterpillar is situated near
its lower lip. The spider’s silk comes from two or three pairs of
spinnerets which are fingerlike in form, and upon the end of each are
many small tubes from which the silk is spun. The silk is in a fluid
state as it issues from the spinnerets, but it hardens immediately
on contact with the air. In making their webs, spiders produce two
kinds of silk, one is dry and inelastic, making the framework of the
web; the other is sticky and elastic, clinging to anything that it
touches. The body and the legs of spiders are usually hairy.
LESSON CX
COBWEBS
_Leading thought_--The cobwebs which are found in the corners of
ceilings and in other dark places in our houses, are made by the
house spider which spins its web in these situations for the purpose
of catching insects.
_Method_--The pupils should have under observation a cobweb in a
corner of a room, preferably with a spider in it.
_Observations_--1. Is the web in a sheet or is it a mass of
crisscrossed, tangled threads? How are the threads held in place?
2. What is the purpose of this web? Where does the spider hide?
Describe its den.
3. If a fly becomes tangled in a web, describe the action of the
spider. Does the spider eat all of the fly? What does it do with the
remains?
4. If the spider is frightened, what does it do? Where does the
silken thread come from, and how does its source differ from the
source of the silken thread spun by caterpillars?
5. Imprison a spider under a tumbler or in a vial, and look at it
very carefully. How many legs has it? How does the spider differ from
insects in this respect? How many sections are there to the body? How
does the spider differ from insects in this respect?
6. Look closely at the head. Can you see the hooked jaws, or fangs?
Can you see the palpi on each side of the jaws? Where are the
spider’s eyes? How many pairs has it?
* * * * *
_When the tangled cobweb pulls
The cornflower’s cap awry,
And the lilies tall lean over the wall
To bow to the butterfly
It is July._
--SUSAN HARTLEY SWETT.
[Illustration:
Photo by J. H. Comstock.
_A funnel web._]
THE FUNNEL WEB
_Teacher’s Story_
“_And dew-bright webs festoon the grass
In roadside fields at morning._”
--ELIZABETH AKERS.
Sometimes on a dewy morning, a field will seem carpeted with these
webs, each with its opening stretched wide, and each with its narrow
hallway of retreat. The general shape of the web is like that of a
broad funnel with a tube leading down at one side. This tube is used
as a hiding place for the spider, which thus escapes the eyes of its
enemies, and also keeps out of sight of any insects that might be
frightened at seeing it, and so avoid the web. But the tube is no
cul-de-sac; quite to the contrary, it has a rear exit, through which
the spider, if frightened, escapes from attack.
The web is formed of many lines of silk crossing each other
irregularly, forming a firm sheet. This sheet is held in place by
many guy-lines, which fasten it to surrounding objects. If the web is
touched lightly, the spider rushes forth from its lair to seize its
prey; but if the web be jarred roughly, the spider speeds out through
its back door and can be found only with difficulty. The smaller
insects of the field, such as flies and bugs, are the chief food of
this spider; it rarely attempts to seize a grown grasshopper.
The funnel-shaped webs in dark corners of cellars are made by a
species which is closely related to the grass spider and has the same
general habits, but which builds in these locations instead of in the
grass.
LESSON CXI
THE FUNNEL WEB
_Leading thought_--The grass spider spins funnel-shaped webs in the
grass to entrap the insects of the field. This web has a back door.
_Method_--Ask the pupils to observe a web on the grass with a spider
within it.
_Observations_--1. What is the general shape of the web? Is there a
tunnel leading down from it? Why is it called a funnel web?
2. Of what use is the funnel tube, and what is its shape? Where does
it lead, and of what use is it to the spider? Can you corner a spider
in its funnel tube? Why not?
3. How is the web made? Is there any regularity in the position of
the threads that make it? How is it stayed in place?
4. Touch the web lightly, and note how the spider acts? Jar the web
roughly, and what does the spider do?
5. What insects become entangled in this web?
6. Compare this web with similar funnel webs found in corners of
cellars, sheds or piazzas, and see if you think the same kind of
spider made both.
THE ORB-WEB
_Teacher’s Story_
[Illustration: O]
Of all the structures made by the lower creatures, the orb-web of
the spider is, beyond question, the most intricate and beautiful in
design, and the most exquisite in workmanship. The watching of the
construction of one of these webs is an experience that brings us
close to those mysteries which seem to be as fundamental as they are
inexplicable in the plan of the universe. It is akin to watching the
growth of a crystal, or the stars wheeling across the heavens in
their appointed courses.
The orb-web of the large, black and yellow garden spider is, perhaps,
the best subject for this study, although many of the smaller orbs
are far more delicate in structure. These orb-webs are most often
placed vertically, since they are thus more likely to be in the path
of flying insects. The number of radii, or spokes, differs with
the different species of spiders, and they are usually fastened
to a silken framework, which in turn is fastened by guy-lines to
surrounding objects. These radii or spokes are connected by a
continuous spiral line, spaced regularly except at the center or hub;
this hub or center is of more solid silk, and is usually surrounded
by an open space; and it may be merely an irregular network, or it
may have wide bands of silk laid across it.
The radii or spokes, the guy-lines, the framework and the center of
the web are all made of inelastic silk, which does not adhere to an
object that touches it. The spiral line, on the contrary, is very
elastic, and adheres to any object brought in contact with it.
An insect which touches one of these spirals and tries to escape,
becomes entangled in the neighboring lines and is thus held fast
until the spider can reach it. If one of these elastic lines be
examined with a microscope, it is a most beautiful object. There are
strung upon it, like pearls, little drops of sticky fluid, which
render it not only elastic but adhesive.
Some species of orb-weavers remain at the center of the web, while
others hide in some little retreat near at hand. If in the middle,
the spider always keeps watchful claws upon the radii of the web
so that if there is any jarring of the structure by an entrapped
insect, it is at once apprised of the fact; if the spider is in a
den at one side, it keeps a claw upon a trap line which is stretched
tightly from the hub of the web to the den, and thus communicates
any vibration of the web to the hidden sentinel. When the insect
becomes entangled, the spider rushes out and envelops it in a band
of silk, which feat it accomplishes, by turning the insect over and
over rapidly, meanwhile spinning a broad, silken band which swathes
it. It may bite the insect before it begins to swathe it in silk, or
afterwards. It usually hangs the swathed insect to the web near where
it was caught, until ready to eat it; it then takes the prey to the
center of the web, if there is where the spider usually sits, or to
its den at one side, if it is a den-making species, and there sucks
the insect’s blood, carefully throwing away the hard parts.
[Illustration: _A dewy morning._
Insect Life, Comstock.]
The spider does not become entangled in the web, because, when it
runs it steps upon the dry radii and not upon the sticky spiral
lines. During the busy season, the spider is likely to make a new web
every twenty-four hours, but this depends largely upon whether the
web has meanwhile been destroyed by large insects.
The spider’s method of making its first bridge is to place itself
upon some high point and, lifting its abdomen in the air, to spin
out on the breeze a thread of silk. When this touches any object, it
adheres, and the spider draws in the slack until the line is “taut;”
it then travels across this bridge, which is to support its web, and
makes it stronger by doubling the line. From this line, it stretches
other lines by fastening a thread to one point, and then walking
along to some other point, spinning the thread as it goes and holding
the line clear of the object on which it is walking by means of one
of its hind legs. When the right point is reached, it pulls the line
tight; fastens it, and then, in a similar fashion, proceeds to make
another. It may make its first radius by dropping from its bridge
to some point below; then climbing back to the center, it fastens
the line for another radius, and spinning as it goes, walks down and
out to some other point, holding the thread clear and then pulling
it tight before fastening it. Having thus selected the center of the
web, it goes back and forth to and from it, spinning lines until
all of the radii are completed and fastened at one center. It then
starts at the center and spins a spiral, laying it onto the radii
to hold them firm. However, the lines of this spiral are farther
apart and much more irregular than the final spiral. Thus far, all
of the threads the spider has spun are inelastic and not sticky; and
this first, or temporary spiral is used by the spider to walk upon
when spinning the final spiral. It begins the latter at the outer
edge instead of at the center, and works toward the middle. As the
second spiral progresses, the spider with its jaws cuts away the
spiral which it first made, and which it has used as a scaffolding. A
careful observer may often see remnants of this first spiral on the
radii between the lines of the permanent spiral. The spider works
very rapidly and will complete a web in a very short time. The final
spiral is made of the elastic and adhesive silk.
_References_--Comstock’s Manual; Common Spiders, Emerton; The Spider
Book, Comstock; Nature’s Craftsmen, McCook.
LESSON CXII
THE ORB-WEB
_Leading thought_--No structure made by a creature lower than man is
so exquisitely perfect as the orb-web of the spider.
_Method_--There should be an orb-web where the pupils can observe it,
preferably with the spider in attendance.
_Observations_--1. Is the orb-web usually hung horizontally or
vertically?
2. Observe the radii, or “spokes,” of the web. How many are there?
How are they fastened to surrounding objects? Is each spoke fastened
to some object or to a framework of silken lines?
3. Observe the silken thread laid around the spokes. Is it a spiral
line or is each circle complete? Are the lines the same distance
apart on the outer part of the web as at the center? How many of the
circling lines are there?
4. Is the center of the web merely an irregular net, or are there
bands of silk put on in zigzag shape?
5. Touch any of the “spokes” lightly with the point of a pencil.
Does it adhere to the pencil and stretch out as you pull the pencil
away? Touch one of the circling lines with a pencil point, and see if
it adheres to the point and is elastic. What is the reason for this
difference in the stickiness and elasticity of the different kinds of
silk in the orb-web?
6. If an insect touches the web, how does it become more entangled by
seeking to get away?
7. Where does the spider stay, at the center of the web or in a
little retreat at one side?
8. If an insect becomes entangled in the web, how does the spider
discover the fact and act?
9. If the spider sits at the middle of the orb, it has a different
method for discovering when an insect strikes the web than does the
spider that hides in a den at one side. Describe the methods of each.
10. How does the spider make fast an insect? Does it bite the insect
before it envelops it in silk? Where does it carry the insect to feed
upon it?
11. How does the spider manage to run about its web without becoming
entangled in the sticky thread? How often does the orb-weaver make a
new web?
[Illustration: _A partially completed orb-web._
a, the temporary spiral stay line; b, the sticky spiral line; c, the
fragments of the temporary spiral hanging to a radius.
Comstock’s Manual.]
_How an Orb-web is Made_
Spiders may be seen making their webs in the early morning or in the
evening. Find an orb-web with a spider in attendance; break the web
without frightening the spider and see it replace it in the early
evening, or in the morning about daybreak. An orb-weaver may be
brought into the house on its web, when the web is on a branch, and
placed where it will not be disturbed, and thus be watched at leisure.
_Observations_--1. How does the spider manage to place the supporting
line between two points?
2. How does it make the framework for holding the web in place?
3. How does it make the first radius?
4. How does it make the other radii and select the point which is to
be the center of the web?
[Illustration:
_The zigzag strengthening band at center of an orb-web._ ]
5. How does it keep the line which it is spinning clear of the line
it walks upon?
6. After the radii are all made, are they fastened at the center?
7. How and where does the spider first begin to spin a spiral? Are
the lines of this spiral close together or far apart? For what is the
first spiral used?
8. Where does it begin to spin the permanent spiral? Where does it
walk when spinning it? By the way it walks on the first spiral, do
you think it is sticky and elastic? What does it do with the first
spiral while the second one is being finished?
9. If the center of the web has a zigzag ribbon of silk, when was it
put on?
10. How many minutes did it take the spider to complete the web?
_Supplementary reading_--“Argiope of The Silver Shield,” Insect
Stories, Kellogg.
[Illustration: _A filmy-dome web with its maker._
Photo by J. H. Comstock.]
THE FILMY DOME
_Teacher’s Story_
[Illustration: L]
Like bubbles cut in half, these delicate domes catch the light rays
and separate them like a prism into waves of rainbow colors. One of
these domes is usually about the size of an ordinary bowl, and is
suspended with the opening on the lower side. It is held in place by
many guy-lines which attach it to surrounding objects. Above a filmy
dome are always stretched many crisscrossed threads for some distance
up. These are for the purpose of hindering the flight of insects, so
that they will fall into the web. The little spider, which always
hangs, back downward, just below the center of the dome, rushes to
its prey from the lower side, pulls it through the meshes of the web,
and feeds upon it. But any remains of the insect or pieces of sticks
or leaves which may drop upon the web, it carefully cuts out and
drops to the ground, mending the hole very neatly.
LESSON CXIII
THE FILMY DOME
_Leading thought_--One little spider spins a filmy dome, beneath the
apex of which it hangs, back downward, awaiting its prey.
_Method_--On a sunny day in late summer or early autumn, while
walking along woodland paths, the careful observer is sure to see
suspended among the bushes or in the tops of weeds, or among dead
branches of young hemlocks, the filmy dome webs. They are about as
large as a small bowl, and usually so delicate that they cannot
be seen unless the sun shines upon them; they are likely to be
exquisitely iridescent under the sun’s rays. Such a dome may be
studied by a class or by the pupils individually.
_Observations_--1. Where did you discover the filmy dome? What is
the size of the dome? Does it open above or below? How is it held in
place?
2. Are there many crisscrossed threads extending above the dome? If
so, what do you think they are for?
3. Where does the spider stay? Is the spider large and heavy, or
small and delicate?
4. What does the spider do if an insect becomes entangled in its web?
5. Throw a bit of stick or leaf upon a filmy dome web, and note what
becomes of it.
* * * * *
“_With spiders I had friendship made,
And watch’d them in their sullen trade._”
--PRISONER OF CHILLON.
BALLOONING SPIDERS
_Teacher’s Story_
[Illustration: I]
If we look across the grass some warm sunny morning or evening of
early fall, we see threads of spider silk clinging everywhere; these
are not regular webs for trapping insects, but are single threads
spun from grass stalk to grass stalk until the fields are carpeted
with glistening silk. We have a photograph of a plowed field, taken
in autumn, which looks likes the waves of a lake; so completely is
the ground covered with spider threads that it shows the “path of the
sun” like water.
When we see so many of these random threads, it is a sign that the
young spiders have started on their travels, and it is not difficult
then to find one in the act. The spiderling climbs up some tall
object, like a twig or a blade of grass, and sends out its thread of
silk upon the air. If the thread becomes entangled, the spiderling
sometimes walks off on it, using it as a bridge, or sometimes it
begins again. If the thread does not become entangled with any
object, there is soon enough given off, so that the friction of the
air current upon it supports the weight of the body of the little
creature, which promptly lets go its hold of earth as soon as it
feels safely buoyed up, and off it floats to lands unknown. Spiders
thus sailing through the air have been discovered in mid-ocean.
Thus we see that the spiders have the same way of distributing their
species over the globe, as have the thistles and dandelions. It has
been asked what the spiders live upon while they are making these
long journeys, especially those that have drifted out to sea. The
spider has very convenient habits of eating. When it finds plenty
of food it eats a great deal; but in time of famine it lives on,
apparently comfortably, without eating. One of our captive spiders
was mislaid for six months and when we found her she was as full of
“grit” as ever, and she did not seem to be abnormally hungry when
food was offered her.
* * * * *
“_A noiseless, patient spider,
I mark’d where, on a little promontory, it stood isolated:
Mark’d how to explore the vacant, vast surrounding,
It launch’d forth filament out of itself:
Ever unreeling them--ever tirelessly speeding them._
“_And you, O my soul, where you stand,
Surrounded, surrounded, in measureless oceans of space,
Ceaselessly, musing, venturing, throwing, seeking the spheres
to connect them;
Till the bridge you will need be form’d--till the ductile
anchor hold;
Till the gossamer thread you fling catch somewhere, O my
soul._”
--WALT WHITMAN.
LESSON CXIV
BALLOONING SPIDERS
_Leading thought_--The young of many species of spiders scatter
themselves like thistle seeds in balloons which they make of silk.
_Method_--These observations should be made out of doors during some
warm sunny day in October. Read Nature’s Craftsmen, McCook, p. 182.
_Observations_--1. Look across the grass some warm sunny morning or
evening of early fall, and note the threads of spider silk gleaming
everywhere, not regular webs, but single threads spun from grass
stalk to grass stalk, or from one object to another, until the ground
seems glistening with silk threads.
2. Find a small spider on a bush, fence post, or at the top of some
tall grass stalk; watch it until it begins to spin out its thread.
3. What happens to the thread as it is spun out?
4. If the thread does not become entangled in any surrounding object
what happens? If the thread does become entangled, what happens?
5. How far do you suppose a spider can travel on this silken
aeroplane? Why should the young spider wish to travel?
THE WHITE CRAB-SPIDER
_Teacher’s Story_
[Illustration: T]
There are certain spiders which are crablike in form, and their legs
are so arranged that they can walk more easily sidewise or backward
than forward. These spiders spin no webs, but lie in wait for their
prey. Many of them live upon plants and fences and, in winter, hide
in protected places.
[Illustration: _A common crab-spider._]
The white crab-spider is a little rascal that has discovered the
advantage of protective coloring as a means of hiding itself from the
view of its victims, until too late to save themselves; the small
assassin always takes on the color of the flower in which it lies
concealed. In the white trillium, it is greenish white; while in the
golden-rod its decorations are yellow. It waits in the heart of the
flower, or in the flower clusters, until the visiting insect alights
and seeks to probe for the nectar; it then leaps forward and fastens
its fangs into its struggling victim. I have seen a crab-spider in
a milkweed attack a bee three times its size. This spider was white
with lilac or purple markings. If disturbed, the crab-spider can walk
off awkwardly or it may drop by a silken thread. It is especially
interesting, since it illustrates another use for protective
coloring; and also because this species seems to be able to change
its colors to suit its surroundings.
LESSON CXV
THE WHITE CRAB-SPIDER
_Leading thought_--1. The white crab spider has markings upon its
body of the same color as the flower in which it rests and is thus
enabled to hide in ambush out of the sight of its victims--the
insects which come to the flower for nectar.
_Method_--Ask the children to bring one of these spiders to school in
the flower in which it was found; note how inconspicuous it is, and
arouse an interest in the different colors which these spiders assume
in different flowers.
_Observations_--1. What is the shape of the body of the crab-spider?
Which of the legs are the longest? Are these legs directed forward or
backward?
2. How is the body marked? What colors do you find upon it? Are the
colors the same in the spiders found in the trilliums, as those in
other flowers? Why is this? Do you think that the color of the spider
keeps it from being seen?
3. Place the white spider which you may find in a trillium in a
daffodil, and note if the color changes.
4. Do the crab-spiders make webs? How do they trap their prey?
[Illustration: _Crab-spiders on golden-rod._
This species is white when lurking in the white trillium and yellow
when among flowers of the golden-rod.
Photo by Slingerland.]
HOW THE SPIDER MOTHERS TAKE CARE OF THEIR EGGS
_Teacher’s Story_
[Illustration: P]
Protecting her eggs from the vicissitudes of the weather seems to be
the spider mother’s chief care; though at the same time and by the
same means, she protects them from the attacks of predacious insects.
Many of the species make silken egg-sacs, which are often elaborate
in construction, and are carefully placed in protected situations.
Often a little silvery disk may be seen attached to a stone in a
field. It resembles a circular lichen on the stone, but if it is
examined it is found to consist of an upper, very smooth, waterproof
coat, while below is a soft, downy nest, completely enfolding the
spider’s eggs.
The egg-sacs of the cobweb weavers are often found suspended in their
webs. One of the large orbweavers makes a very remarkable nest, which
it attaches to the branches of weeds or shrubs. This sac is about
as large as a hickory nut, and opens like a vase at the top. It is
very securely suspended by many strong threads of silk, so that the
blasts of winter cannot tear it loose. The outside is shining and
waterproof, while inside it has a fit lining for a spiderling cradle.
Dr. Burt G. Wilder studied the development of the inmates of one of
these nests by cutting open different nests at different periods of
the winter. In the autumn, the nest contained five hundred or more
eggs. These eggs hatched in early winter but it seemed foreordained
that some of the little spiders were born for food for their stronger
brethren. They seemed resigned to their fate, for when one of these
victims was seized by its cannibalistic brother, it curled up its
legs and submitted meekly. The result of this process was that, out
of the five hundred little spiders hatched from the eggs, only a few
healthy and apparently happy young spiders emerged from the nest in
the spring, sustained by the nourishment afforded them by their own
family, and fitted for their life in the outside world.
[Illustration: _A wolf-spider carrying her egg-sac._]
Some spiders make a nest for their eggs within folded leaves, and
some build them in crevices of rocks and boards.
The running spiders, which are the large ones found under stones,
make globular egg-sacs; the mother spider drags after her this
egg-sac attached to her spinnerets; the young, when they hatch, climb
upon their mother’s back, and there remain for a time.
LESSON CXVI
THE NESTS OF SPIDERS
_Leading thought_--The spider mothers have many interesting ways of
protecting their eggs, which they envelop in silken sacs and place in
safety.
_Method_--Ask the pupils to bring in all the spider egg-sacs that
they can find. Keep some of them unopened, and open others of the
same kind, and thus discover how many eggs are in the sac, and how
many spiderlings come out. This is a good lesson for September and
October.
_Observations_--1. In what situation did you find the nest? How was
it protected from rain and snow? To what was it attached?
2. Of what texture is the outside of the sac? Is the outside made of
waterproof silk? What is the texture of the lining?
3. How many eggs in this sac? What is the color of the eggs? When
do the spiderlings hatch? Do as many spiders come out of the sac as
there were eggs? Why is this?
[Illustration: _The egg-sac of the large, black and yellow
garden-spider suspended for the winter in a branch of golden-rod._
Photo by Slingerland.]
[Illustration]