A HOME-MADE MICROSCOPE, AND HOW TO USE IT
BY FREDERICK LEROY SARGENT
XIII.--HOW TO SEE A DANDELION.
A simple microscope, some mounted needles, a sharp knife and a pair of
small forceps, are the only things needed to begin with.
There are many kinds of simple microscopes sold, some of which are of
moderate price and answer every purpose; but if one has a little
mechanical skill the cheapest way is to buy a magnifier and make the
rest of the microscope one's self. What is known as the "bellows
pattern," with three lenses, is one of the best of the cheaper forms of
magnifiers, and is an admirable little instrument.
_Fig. 1_ shows a home-made microscope ready for use. It will be seen
that the main part consists of a wooden box having a hole in the top and
open in front. To the back is attached a cork by means of a piece of
thin metal as shown in _fig. 2_. Through this cord slides a rod on which
slides another cork. A piece of brass wire has one end wound round the
upper cork while the other end projects as an arm at right angles to the
rod, and this projecting end sharpened and upturned, passes through
holes drilled in the handle of the magnifier, and thus supports it. The
lenses are focused, _i. e._ brought to the right distance from the
object viewed, by sliding the cork up and down on the rod.
[Illustration: FIG. 1.]
The object rests on a piece of glass laid over the hole in the top of
the box. A piece of wood covered with white paper and placed below the
object at an angle of about forty-five degrees answers for a reflector
to illuminate those objects through which the light can pass. The pure
white surface is better for the purpose than a mirror.
[Illustration: FIG. 2.]
The most delicate part of the construction is making the holes in the
corks for the rod to slide through. This may be done perfectly, however,
by making the holes with a rat-tail file, trying the rod now and then
until it moves just right. The best thing for the rod is a piece of
brass wire one quarter of an inch thick; a lead pencil however is a good
substitute. Before bending the end of the brass wire arm it is well to
heat it red-hot at the point of bending, to take out the temper: as
otherwise it may break. The holes in the handle of the magnifier should
be drilled as near the front as possible and so arranged that when the
magnifier is in position the smallest lens will be near the object.
[Illustration: FIG. 3.]
The mounted needles are shown in _fig. 3_. One pair of each kind will be
enough to start with. To make one, take a fine needle, break off about a
third, so it will not be too long and springy; then with a pair of
pincers force it into the handle point first, withdraw it and finally
force it in again with the point out. It may be easily bent with the
pincers by first heating it to redness in a flame. When bent, heat it
red once more and plunge quickly into water to re-temper it. Rubbing on
an oil stone may be necessary to remove roughness. Should the handles
show any tendency to split, it would be well to wrap the end tightly
with waxed thread.
The forceps (_fig. 4_) may be purchased either of brass or steel at no
great expense. Although not necessary it is more convenient to have them
curved than straight.
[Illustration: FIG. 4.]
If the reader will carefully follow the directions given below and
endeavor to see for himself all the parts spoken of, he will probably
have very little difficulty afterward in the use of the instruments just
described; and the enjoyment he will have when he has learned how to
examine little things, will amply repay for careful and persistent
efforts at the start. Get a Dandelion in full bloom and also one that
has gone to seed.
Have the microscope and the other instruments ready for use. The best
place to work is on a table in front of a window where there is plenty
of light, but not the direct rays of the sun.
Now cut the blossom in halves from the stem up. It will be seen that the
stem is hollow and ends above in a cushion-like expansion. From the
upper surface of this grow a number of little flowers, while from the
sides there sprang two rows of little green organs that enclose the
flower cluster like a cup. Remove one of the flowers with the forceps
and place it in a drop of water on the glass stage of the microscope.
Examine with one and one half inch power.[A]
Be careful to get just the focus. You are now ready to see the general
form of the flower. At the base is a little body with roughened sides
and slightly narrowed above (the ovary). Springing from the top of the
ovary are a number of fine bristles (the pappus). Inside the bristles is
a yellow portion, tubular below and flat above (the corolla).
Projecting from the tube of the corolla is a little yellow rod (the top
of the stamens joined together); and coming from among the stamens are
two slender recurved organs (the stigmas).
Now take a mounted needle in each hand and holding one needle on the
flat part of the corolla split open the tubular part with the other. By
keeping the lower part spread open with the needles, you will see that a
number of delicate yellow threads grow from the sides of the corolla and
are connected with the yellow stamen rod. These threads are another part
of the stamens. In the middle of the flower is a single thread-like
organ (the style) which comes from the top of the ovary and passing
through the stamens projects beyond them, divided into two stigmas.
Most of my readers have probably studied enough botany to know the names
of the different parts of a flower, but very likely many of them do not
recognize the parts of the Dandelion flower as looking anything like the
parts of the flower with which they are familiar.
Before proceeding further, therefore let us take a Morning-Glory
flower--which you all know and can easily obtain, or at least some
flower like it--and let us see that the parts of the two correspond.
Commencing in the centre we find in both a pistil, consisting of an
ovary at the base and a stigma at the top and a style between. In the
Dandelion the stigma is split in halves, while in the morning-glory it
is not split but has three little knobs. Around the pistil come the
stamens in each case. Each stamen is composed of two parts: a slender
stem (the filament) and a little sac at the end (the anther) which is
filled with pollen dust. In both cases the filaments grow out of the
sides of the corolla. But while in the Morning-Glory the anthers are
entirely free from one another, in the Dandelion they are joined
together by their sides and form a tube around the style. The corolla in
both cases is all of one piece, but in the Dandelion it is as if the
upper part of the corolla were split open one side and then made flat.
Instead of a green calyx as in the Morning-Glory, the Dandelion has a
number of delicate white bristles. And, finally, in the Morning-Glory
both the calyx and corolla grow out from below the ovary, while in the
Dandelion its calyx of bristles and its corolla issue from above the
ovary. So after all, you will see that corresponding organs are in both,
and the difference between the two flowers is not so great as one might
think at first.
Let the different parts of the Dandelion be examined now more minutely.
First take some of the bristles and examine them with one quarter inch
power. They are not perfectly smooth, but are more or less saw-like on
the edge. With the same power look at other parts of the flower; notice
the hairiness of the stigmas, the pollen grains coming out of the
anthers (some grains may be found on the stigmas) also the roughness of
the ovary and the delicate ribs or veins in the corolla. Examine one of
the seed-like fruits with one and one half inch power. It is a ripened
ovary. Compare the fruit with the ovary of a flower. The nutlet has
become hard, rougher and more strongly ribbed. The narrowed upper part
of the ovary has become much elongated and the pappus is spread out like
an inverted umbrella.
Examine some bristles with one quarter inch power. They show the
saw-like edges much more developed than in the younger bristles of the
flower. We see throughout a beautiful adaptation of every part for
fitting the little parachute to be carried long distances by the wind
and finally to catch on some suitable place in which to sprout.
XIV.--HOW TO SEE A BUMBLE BEE.
You will first need to catch your Bumble Bee. A little chloroform poured
on one will kill it instantly. Make a general examination at the outset
of the insect. The outside of the body is horny and covered thickly with
hairs. On the upper side the hairs are much more numerous than on the
under side. The whole body is divided into three regions: the head,
bearing the feelers and mouth-parts; a middle part (thorax) bearing the
four wings and six legs; and a hind part (abdomen) armed with the sting.
Remove the head and examine with one and one half inch power. At the
sides are two prominent oval bodies (compound eyes) which seem to be
crossed by five lines; near the top of the head, between the compound
eyes, are three little shiny bead-like organs (simple eyes); starting
from about the middle of the face are the two feelers (antennae) and at
the lower part of the head are the mouth-parts. The sides, top and front
of the head are all covered with hair.
Examine one of the compound eyes with one fourth inch power. The surface
is made up of innumerable little facets, something like a cut diamond.
Cut off a piece of one of the compound eyes, remove some of the black
pigment on the back and examine the piece in a drop of water. Each facet
is a tiny hexagon. Some care is necessary to see them well.
Remove an antenna and examine it with three fourths inch power. It is
thickly covered with minute hairs which give it a velvety appearance.
Count the joints. At the base is the longest joint; at the lower end of
which is a little knob that fits into a socket in the head. The next
joint is quite small while those beyond are much alike.
Scrape the hairs from the face and examine the horny shell with three
fourths inch power. The surface is full of little pits. In the upper
part of the face there is a groove, in the middle of which is one of
the simple eyes. Just below the antennae sockets is a groove which
extends crosswise a short distance on either side and then bends
downwards to the mouth. The portion of the face bounded by this groove
is called the clypeus. At its lower part is hinged a little oblong piece
(labium) which may be moved up and down with a needle.
Melt a piece of sealing wax on the centre of a slip of glass (taking
care not to break the glass by too sudden heating) and before the wax
hardens press the head into it face downwards.
Examine with one inch power. The hole near the top of the head shows the
position of the neck. The portion of the head around this hole is
destitute of hairs and is hollowed in, to make room for the rounded
front part of the thorax. Below this one there is another cavity which
contains a portion of the mouth parts when they are retracted. At each
side of the mouth in front of the base of the sucking organs, are the
two jaws (mandibles) each with a little tuft of hair on the outer side.
The jaws move freely to and from each other, sideways instead of up and
down as do the jaws of the higher animals. The sucking apparatus
consists of five pieces viz: two outermost pieces each tapering to a
fine point, two, each of which ends in three little joints and one in
the centre which projects beyond the others. It may be necessary to
spread these out with the needle, to see them well.
Separate the thorax from the rest of the body. Scrape off the hairs on
the back. Two principal grooves extend across the back, one near the
front and one near the hind margin. The thorax is composed of three
divisions and these grooves show where they are joined together. The
hind division bears the hind wings and the hind pair of legs; the middle
division, much the largest division of the three, bears the fore wings
and the middle pair of legs; and the foremost division is quite small
and bears only the front pair of legs.
Remove the wings of one side and examine in a drop of water with one and
one half inch power. The wings consist of a shining transparent membrane
strengthened by numerous horny veins running through it. Examine with
one half inch power. The membrane is seen to be covered with minute
hairs and little dots. On the front edge of the hind wing a short
distance from the outer end is a row of hooks. At a corresponding place
on the hind edge of the fore wing there is a thickening or ridge. When
flying, the hooks catch onto the ridge and thus the wings are held
together and act as one large wing.
Examine this grappling apparatus with one fourth inch power and with the
needles hook the wings together and pull them apart. If you look through
the magnifier while you do this you will get a good idea of the form of
the ridge and of how the hooks catch onto it. Remove one of the
forelegs, being sure that none remains attached to the body. Examine
with one and one half inch power. The extremity is armed with two claws;
then come four short joints followed by one about as long as the others
together. All these make up the foot. The next joint above is the shank,
then comes the thigh and then quite a small joint, the lower hip, and
lastly attached to the body is the upper hip.
Remove the last five joints of the foot (the claw part, and the other
four joints) examine with one third inch power. The claws have each a
branch projecting from the inner edge. Between the claws is a little
velvety pad. Each of the small joints is covered with short closely
appressed hairs and from the lower end of each joint project several
spines. Now examine the remaining long joint of the foot attached to the
shank. At the upper end of the inner side is a deep semicircular notch,
the upper portion of which is light colored. Beside the notch is a
peculiarly shaped movable spine which projects from the lower end of the
shank. This queer arrangement is what the bee uses to clean his feelers.
The reader has probably seen the operation performed by a bee or a wasp.
The leg is thrown over the feeler, the latter is grasped at that
particular bend of the leg where the cleansing apparatus is situated and
then drawn through from base to tip; and this is repeated several times
with each feeler.
Examine with one and one half inch power a leg from each of the other
pairs and compare the corresponding parts. They differ chiefly in size
and in the absence of the cleansing apparatus. You cannot fail to
admire the many beautiful forms of the different portions. On the outer
side of the hind shank is a smooth flattish surface destitute of hairs,
excepting a fringe of long ones at the margin. At this place may
sometimes be found a sticky mass of pollen intended for bee-bread.
Examine the abdomen with one and one half inch power. It is composed of
several wings. If some of the hairs are scraped off this will be shown
more clearly. From the hind extremity projects the sting.
We have far from exhausted all the beautiful and interesting points in
the make-up of a Bumble Bee, not even those that may be seen with the
limited powers of a simple microscope; but probably enough has been said
to show the reader that such things are well worthy of study and it is
hoped that enough directions have been given to render future use of the
instruments comparatively free from difficulty.
XV.--SOME LITTLE THINGS TO SEE.
There is no end to the beautiful and wonderful things one can see with
the simple microscope. Only a few of the more attractive and easily
obtained of these are now to be mentioned.
To begin with, there are ever so many pretty flowers to look at. The
asterworts, that is, such flowers as the daisy, aster, golden rod,
dandelion and thistle, are particularly full of beauty. The blossoms are
all made up of a number of little flowers as in the dandelion; but the
shapes and colors and so forth, of the different kinds are exceedingly
various. Some, such as the asters and daisies, have two kinds of flowers
in the same blossom--flowers with strap-shaped corollas (like the
dandelion's) are arranged along the margin of the blossom, while in the
centre are little flowers with star-shaped corollas presenting a much
different appearance. Flowers of many of the Parsley Family, for
example wild carrot, wild parsnip and caraway, are quite odd. Very
pretty flowers are found among the grasses, sedges and common weeds. The
different trees as they bloom in spring--the maples, elms, willows,
poplars, sassafras and hosts of others--all have flowers that are
perfectly lovely. Most of these flowers need to be picked to pieces
under the magnifier to show up their full beauty. The parts of flowers,
both small and large ones, deserve attention. Frequently one meets with
remarkable forms.
Seeds are highly interesting. They are often handsomely marked with
series of pits or projections, grooves or ridges. One meets with many
curious appendages by means of which the seeds are carried off and sown
at a distance from the plant. Some, like the dandelion, have a parachute
attachment; others have wings to catch the wind, and others still are
covered with hooked spines whereby they become attached to the fur of
animals, there to remain until brushed off onto the ground.
Leaves and stems sometimes have on them beautiful hairs and oil-glands.
The wooly covering of common mullein, for example, is made up of
innumerable slender-branched hairs. These show best when a piece of the
leaf broken off is looked at edgewise.
If you examine the fruit-dots on the backs of the different kinds of
ferns you will be surprised to find how pretty they are and of how many
different shapes. Sometimes the fruit is not borne on the back of the
leaf but forms little clusters by themselves, which are sometimes at the
end of the fern, sometimes in the middle, sometimes on a separate stalk.
Mosses, lichens and sea-weeds are well worth looking at.
Early in the summer an exquisite little fungus called "Cluster cups" may
be found on the underside of barberry leaves. Hawthorn and other plants
have handsome fungi on them later in the season.
By observing closely while out in the fields or woods, one sees hovering
about in swarms, myriads of tiny insects. Under the lens some of them
are very odd, others very beautiful. The easiest way to catch these
little midgets, is to wet the palm of the hand and then sweep it among
them, or in the same way use a piece of sticky paper.
The study of the different parts of insects is one of the most
fascinating of the many uses of the Simple microscope. Although all
insects are made up on the same general plan and corresponding organs
occur in most of them, there is an endless variety in the forms under
which we see the different organs and the uses to which they are put.
Take for example the antennae. In the grasshopper it is long and
threadlike; in the butterflies always ending in a knob; in moths always
tapering to a point, although sometimes threadlike and sometimes much
branched, forming a beautiful plume; in the beetles, sometimes fan-like,
sometimes like a comb; and in other insects assuming still other forms.
Insects' eyes are often colored beautifully. A horse-fly's eyes are
striped. Butterflies' eyes have usually a soft liquid coloring, and
moths' eyes in the dark shine like little fiery beads.
The mouths of insects, such as beetles, grasshoppers and dragon flies,
have strong jaws for biting; flies, bugs, moths and butterflies, have
the mouth-parts transformed into sucking organs, while bees, wasps and
the like have both sucking organs for honey, and biting organs for
leaf-cutting, wood-tearing etc. as we saw was the case in the Bumble
Bee.
Butterflies' wings and moths' wings are covered with little scales of a
variety of shapes. These should be examined attached to the wing to show
their arrangement which is like that of shingles on a roof; but to show
their form they should be looked at when brushed from the wing onto a
piece of glass. Many other peculiarities may be noticed in the wings of
other kinds of insects.
Legs, the same as the other organs, have various forms, markings and
appendages, and so it is with the abdomen and its stings or its
egg-laying apparatus.
The hairs of "Wooly Bears" and caterpillars of that kind are peculiarly
branched.
The four hind pairs of feet in caterpillars are armed each with a row
of little hooks which are used in walking to get a firm hold. The larger
caterpillars show the hooks best.
Sometimes you will find pretty insect eggs on the underside of leaves or
on stems, and also little silken cocoons in similar places. If you are
near a pond-hole, or an old hogshead that collects rain water, you can
find a good many little animals, some of them very frisky--young
mosquitoes or "polywogs," water-fleas, cyclops, little worms, young
dragon-flies and lots of others. When you go to collect them take a
small wide-mouth bottle and, having found a place where there is what
you want, lower your bottle, mouth down, in the midst of them and when
it is well under water turn the mouth upwards. A good many of the
animals will run in with the water. If the first time you do not get
what you want, the second time you may. When you want to examine them at
home you can fish them out with a glass tube and put them in a watch
crystal or on the glass stage of the microscope. In using the tube take
it between the thumb and middle and third fingers, and close the top
with your first finger; then put the lower end of the tube in the water
close to the thing you want to catch; now lift your first finger quickly
and the water will run in the lower end of the tube carrying with it
your little squirmer, unless he has been too quick for you. Close the
top of your tube again and the water will not run out when you remove
the tube, until you lift your finger. Sometimes it takes a good deal of
patience and skill to catch the more agile of the little water animals.
Glass tubes are sold in drug stores for five or ten cents.
If you begin by examining the objects already spoken of, you will while
looking for these be continually discovering for yourselves new objects
possessing new beauties and will soon see that not half the interesting
things you can find have been ever hinted at.
The way to find out about all these things is to go out into the fields
and woods, and form the habit of observing closely what is around you.
Carry your magnifier along and look at this flower, that fern, this
insect, that moss, with different powers of the magnifier; and when you
come across any objects worthy of a more careful examination carry them
home and examine them systematically with Simple microscope, needles,
knife, and so forth. Insects may be kept well in alcohol until winter,
and then careful studies may be made of them.
When using the magnifier in the field, hold it in such a way that the
smallest lens will be nearest the object when the lenses are combined
and be careful not to shade the object with the hand or the hat brim.
Just enough light should fall on the object to make its examination
comfortable for the eyes. If you rest the hand holding the magnifier on
the hand that holds the object, both lens and object can be held much
steadier. When commencing to examine an object it is best to have the
three lenses spread apart, for in this way you can use first the lowest
power then those higher and finally, if you wish to, the three lenses
combined. The dissecting forceps are very handy to have in the field,
both for picking up anything too small for the fingers and for holding
an object to be examined.
A collection of some of these little things preserved and ready for
examination adds greatly to the pleasures of studying them. Of course
all the different kinds of objects cannot be preserved so as to show
their full beauty, but many can be and the following directions will
tell how to make a very good collection:
Seeds, fern-fruit, insects and other opaque objects like these may be
mounted on pasteboard slides. One of these slides consists simply of a
stout piece of pasteboard, having a hole cut in the centre and a piece
of thick paper or cardboard glued on the under side. The object is
attached to the cardboard at the bottom of the hole.
It is best to make a number of these slides at a time. Having procured
some quite thick pasteboard, from old paper boxes, rule lines on the
surface dividing it up into spaces three inches long by one inch wide.
In the centre of each space cut out a hole about half an inch in
diameter. A sharp knife will make a neat square hole or a good round one
may be made with a gun-wad punch. This done, the spaces may be cut apart
with a sharp knife and ruler, along the lines already drawn. Pieces of
cardboard for the backs should be cut a trifle larger than the
pasteboard portion of the slide; after they are glued onto the latter
they may be trimmed down neatly with a pair of scissors. Glue or
mucilage containing glycerine (in the proportion of one or two
teaspoonfuls to an ordinary bottle of mucilage) is the best thing to use
for sticking on the backs. While the slides are drying they should be
either under a weight or in a clamp screwed up tightly, so as to prevent
their twisting out of shape. The mucilage may be prevented from being
squeezed in round the edges of the hole, by taking care when putting it
on not to have it come too near the hole. One or two coats of India Ink
may be painted on the middle of some of the pieces of cardboard, either
before or after they are put onto the slides; and thus a black
background may be obtained for the lighter-colored opaque objects. Many
of the objects will however show best on a white background.
When you have the slides all made, nothing more is needed to mount an
object, than simply to attach it to the bottom of the hole with a
little mucilage and glycerine, or something of that sort, and finally to
write the name of the object on the front part of the slide, and on the
back any desirable notes. A good way to mount such objects as fine seeds
is to put them in the hole loosely and then cover them with a piece of
mica such as will be spoken of presently.
Objects which are to be examined by the light shining through them, for
example a bee's wing or a butterfly's scales, must be mounted on glass
slides.
A glass slide three inches by one is taken, on the centre is placed the
object; over this is laid a thin piece of clear mica three fourths of an
inch square, and this is attached to the glass by pasting narrow strips
of tissue paper around the edges of the cover, partly on the cover and
partly on the slide. Finally the slide is covered with some pretty
colored paper and labeled.
Two pieces of paper are needed to cover each slide. One for the under
part is cut about one and one half by three and one half inches, with a
hole in the centre (round or square). This piece is first pasted on,
the corners being cut and the edges brought over onto the front. The
upper piece, which has a hole in the centre similar to that in the lower
piece, and is cut a trifle larger than the three by one inch slide, is
next pasted on so that the hole will correspond with the one below. The
upper piece of paper is now trimmed down to the slide and the label
attached. Window glass will answer for the slides and you can get any
glazier to cut up a piece for you into the right-sized slips. Mica can
be bought at a stove store, in sheets which may be cut up into three
fourths of an inch squares with a pair of scissors. The mica should be
as clear as you can get it. You will find it handy to have some tissue
paper all mucilaged like postage stamps and cut up in strips the right
size ready to use. The same may be said of the colored paper covers and
the labels.
The dust may be excluded from the uncovered opaque objects by keeping
the mounted slides in small groups, held together by elastic bands. This
will also serve to classify them so that all the insects will be
together, all the seeds, and so on; and the transparent slides may also
be treated in the same way. When an elastic band wears out, it is no
great trouble to replace it.
In working with the Simple microscope there is a fine chance to display
ingenuity, not only in making the instruments and mounting the objects
but in discovering new things to look at and in seeing how much can be
found out about those things which are the most common.
FOOTNOTES:
[A] In these directions "1-1/2 _in._ power" means a lens having
a focus of 1-1/2 inches; "1/2 _in._ power" means a lens or combination
of lenses having a focus of 1/2 inch; and so on. All the different
powers mentioned in the directions may be obtained in the small-sized
3-lens, bellows form magnifier, either by using the lenses singly or
combined in different ways. The magnifying power of any single lens or
simple combination is easily found by dividing 10, by the focus in
inches. Thus the magnifying power of a 1/2 _in._ lens is found in this
way: 10/1/2 = 10x2/1 20. The lens magnifies therefore 20 diameters
_i. e._ makes an object appear twenty times as long and twenty times as
broad as it is.
TRANSCRIBER'S NOTES:
Text in italics is surrounded with underscores: _italics_.
Inconsistencies in hyphenation have been retained from the original.
Obvious typographical errors have been corrected as follows:
Page 8: hundreth changed to hundredth
Page 11: iustrument changed to instrument
Page 15: diferent changed to different
Page 17: he changed to the
Page 20: wil changed to will
Page 44: or changed to of
Page 72: staightened changed to straightened
Page 86: DIFFRENT changed to DIFFERENT
Page 125: fouths changed to fourths