Through a Microscope Part 5

_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 bra.s.s 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, pa.s.ses 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.

[Ill.u.s.tration: FIG. 1.]

The object rests on a piece of gla.s.s 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 pa.s.s. The pure white surface is better for the purpose than a mirror.

[Ill.u.s.tration: 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 bra.s.s wire one quarter of an inch thick; a lead pencil however is a good subst.i.tute. Before bending the end of the bra.s.s 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.

[Ill.u.s.tration: 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 bra.s.s or steel at no great expense. Although not necessary it is more convenient to have them curved than straight.

[Ill.u.s.tration: 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 cus.h.i.+on-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 cl.u.s.ter like a cup. Remove one of the flowers with the forceps and place it in a drop of water on the gla.s.s 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 pa.s.sing 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 k.n.o.bs. 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 b.u.mBLE BEE.

You will first need to catch your b.u.mble 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 h.o.r.n.y 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 s.h.i.+ny 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 k.n.o.b that fits into a socket in the head. The next joint is quite small while those beyond are much alike.

Sc.r.a.pe the hairs from the face and examine the h.o.r.n.y sh.e.l.l 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 gla.s.s (taking care not to break the gla.s.s 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 dest.i.tute 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. Sc.r.a.pe off the hairs on the back. Two princ.i.p.al 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 s.h.i.+ning transparent membrane strengthened by numerous h.o.r.n.y 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 dest.i.tute of hairs, excepting a fringe of long ones at the margin. At this place may sometimes be found a sticky ma.s.s 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 sc.r.a.ped 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 b.u.mble 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 gra.s.ses, sedges and common weeds. The different trees as they bloom in spring--the maples, elms, willows, poplars, sa.s.safras 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 cl.u.s.ters 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 "Cl.u.s.ter 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.