The structure of bacteria is much simpler and more monotonous than the structure of protozoa, and there is no such richness of forms as in ciliates. However, this uniformity and simplicity of structure make bacteria a very good model for many experiments. They are even simpler, and therefore even better as a model, viruses. But about them - later, in a special chapter.
To look at living bacteria, you and I will have to look for more powerful and sophisticated microscopes than those in which you can view ciliates. You can't do without an increase of 600-800 times.
But the source, in which you can always find a wide variety of bacteria, is always available. This is your own mouth. Scrape off plaque and stir it in a drop of water or saliva on a glass slide. This is enough for you to familiarize yourself with the basic forms of bacteria.
If you look at them through an ordinary microscope used in medical and biological laboratories, you will probably be disappointed. You will see grayish, with indistinct contours, very small sticks, balls, threads. Is it possible to compare them with the bizarre, like tropical fish, ciliates?
With what is called a phase contrast microscope, you can see more. The difference between this microscope and the usual one comes down to the fact that particles that are equally transparent to light rays, but with different density they look different here: more dense - darker, less dense - lighter.
It is interesting to observe living bacteria through the so-called dark-field microscope. The light rays here do not go through the observation object into the microscope objective, but from the side. You've probably seen how brightly the specks of dust glow in the sunbeam, which made its way through the curtains or shutters in a dark room.
Bacteria also look about the same in a dark-field microscope - as light dots on a coal-black or brownish background. At the same time, their general outlines are slightly blurred, but the movement of bacteria is clearly visible. And the nature of the movement allows you to recognize the causative agents of some diseases.
Photo: U.S. Geological Survey
Photo: Umberto Salvagnin
Other bacteria do not have flagella necessary for movement. But this does not mean that they will be motionless in the field of view of the microscope. No, it will seem to you that the bacteria are moving, and all at once, like ants in a torn anthill. However, this is not an independent, active movement of the microbe, but the so-called Brownian movement.
The Brownian motion of any small particles floating in a liquid (by no means only microbes) is a consequence of the random thermal motion of the molecules of this liquid. Molecules press on the particle from all sides, and it is, so to speak, "marking time".
But if under the microscope there are motile bacteria, then you will see how quickly they cross the field of view, freeze in place, and then rush further again. It is especially interesting to observe the spirochetes, similar to the revived spiral from electric stove... They are so thin that it is difficult to see a living spirochete under an ordinary microscope.
In a dark-field microscope, they are much better visible. You will probably find them in plaque; just take a good look - it is best to look for spirochetes while they are moving. They either swim, wriggling like snakes, or twitch in place and even fold in half.
Living bacteria are not as convenient to see through a microscope as dead and stained ones.
With what magnification is it desirable to purchase a microscope in order to see microorganisms in ACC?
The details of the structure of these organisms were studied precisely on colored preparations. To stain bacteria, you need to put them on the glass (as they say, make a smear), dry it, warm it up on a burner flame (so that the cells are better tinted later) and drop a drop of special paint on the smear.
If you find yourself in a microbiological laboratory, then, of course, there is a set of various paints. One of the most common is methylene blue. Since it is part of the ink for a fountain pen, for lack of the best, you can splash a drop of ink on the smear. After 6-8 minutes, the paint must be washed off with water and the smear dried.
Depending on what type of bacteria was colored, you will see balls or sticks under the microscope - straight, curved, or similar to a comma. Chains can form from sticks and balls. The balls are sometimes grouped into groups of four, eight, and sixteen. Some sticks have bulges at the ends like a match head. These are the main forms of bacteria.
However, so short description resembles the words of one philosopher who defined man as a biped without feathers. In bacteria, even the most stained in a simple way, you can find quite a few features of their structure. We will discuss some of these features here.
Rod-shaped bacteria in nature are the most. The very word "bacterium" in Greek means "stick". One of the most common microbes, the so-called E. coli, is shaped like a long oval. E. coli lives in the colon; one gram of human feces can contain 2 billion of these microorganisms (imagine how many of them get into the external environment in a populated area!).
Pathogenic microbes - pathogens of dysentery, typhoid, paratyphoid fever - are indistinguishable from E. coli in shape. The causative agent of anthrax is also a stick, but with chopped off ends. Anthrax bacteria are often arranged in long chains.
The causative agents of tetanus, gas gangrene and many other diseases are in the form of a stick.
Sometimes you can find the name "cholera comma". Indeed, the so-called vibrios are like a comma. These include the causative agent of cholera. Just do not imagine the cholera comma in the form of a tadpole, as Mayakovsky liked to draw it in "Windows of ROSTA". It is rather a curved stick of uniform thickness. Strictly speaking, this is not even a stick, but a segment of a spiral, one of its incomplete turns.
The globular bacteria are called cocci. Cocci, collected in bunches resembling grapes, are called staphylococci. Some of them, getting into wounds or scratches, cause suppuration and cause serious illnesses in young children.
Streptococci - microbes that look like beads or rosary beads - cause a lot of misfortune to a person. They cause erysipelas, sore throat, and even heart disease - endocarditis. Cocci, located in two - diplococci - a person is obliged to such diseases as meningitis, pneumonia, gonorrhea.
It is easy to determine the shape of bacteria in a stained smear, but it is impossible to study the structure of a bacterial cell in all details. And if we already know a lot about the structure of bacteria, then this was helped by special methods of staining them and studying them under an electron microscope.
- microscopic method: light, phase contrast, fluorescent, electronic;
- cultural method (bacteriological, virological);
- biological method (contamination of laboratory animals);
- molecular genetic method (PCR - polymerase chain reaction)
- serological method - detecting antigens of microorganisms or antibodies to them;
Methods for preparing preparations for microscopy. With the help of a light microscope, microorganisms can be studied, both in a living and in a colored state. In the study of microbes in a living state, you can get an idea of the size, shape and nature of their movement. Sometimes inside a living cell, shiny, highly refracting light granules and spores are visible. To study microbes in a living state, preparations of a hanging and crushed drop are prepared. To prepare a hanging drop preparation (Fig. 19), a small drop of the test material suspended in a liquid (isotonic sodium chloride solution, mesopatamia broth) is applied to the center of the cover glass with a bacteriological loop. Then take special glass with a hole in the center and the edges are smeared with vaseline oil. Cover the drop of the test material on the cover glass with the well of the glass slide so that the drop is in the center of the well. Press lightly on the slide and turn quickly. At correct preparation of the drug, the drop hangs in the hole. Vaseline oil protects it from drying out.
A crushed drop preparation is prepared by applying a drop of material suspended in a liquid onto a glass slide, which is then covered with a coverslip.
LIGHT OPTICAL MICROSCOPY
A microscope is used for light microscopy - an optical device that allows you to observe small objects. Image magnification is achieved by a system of condenser lenses, objective and eyepiece. A condenser located between the light source and the object under study collects the light rays in the field of the microscope. The objective creates an image of the microscope field inside the tube. The eyepiece magnifies this image and makes it possible to perceive it with the eye.
Home microscopy
The resolution limit of a microscope (the minimum distance at which two objects are distinguishable) is determined by the wavelength of the light wave and the lens aperture. The theoretically possible resolution limit of the light microscope is 0.2 μm; real resolution can be increased by increasing the aperture of the optical system, for example, by increasing the refractive index. The refractive index (immersion) of liquid media is greater than the refractive index of air (n = 1.0); for microscopy, several immersion media are used: oil, glycerol, water. The mechanical part of the microscope includes a tripod, a stage, macro- and micrometric screws, a tube, a tube holder.
Dark field microscopy allows you to observe live bacteria. For this, a dark-field condenser is used, which highlights the contrasting structures of the unpainted material. Before starting work, the light is installed and centered over the bright field, then the bright-field condenser is removed and replaced with an appropriate system (for example, OI-10 or OI-21). The preparation is prepared according to the "crushed drop" method, making it as thin as possible (the thickness of the cover glass should not be thicker than 1 mm). The observed object looks like it is lit in a dark field. In this case, the rays from the illuminator fall on the object from the side, and only scattered rays enter the microscope lenses. Vaseline oil is suitable as an immersion liquid.
Phase contrast microscopy allows you to study live and unpainted objects by increasing their contrast. When light passes through colored objects, the amplitude of the light wave changes, and when passing through uncolored objects, the phase of the light wave occurs, which is used to obtain a high-contrast image in phase contrast and interference microscopy. To increase the contrast, the phase rings are coated with a metal that absorbs direct light without affecting the phase shift. A special condenser with a diaphragm revolver and a centering device is used in the optical system of the microscope; the lenses are replaced with immersion apochromatic lenses.
Polarizing microscopy provides images of unstained anisotropic structures (such as collagen fibers, myofibrils, or microbial cells). The principle of the method is based on the study of an object in light formed by two beams polarized in mutually perpendicular planes.
Interference microscopy combines the principles of phase contrast and polarization microscopy. The method is used to obtain a contrasting three-dimensional image of uncolored objects. The principle of the method is based on the bifurcation of the light flux in a microscope; one ray passes through the object, the other passes it. Both beams are connected in the eyepiece and interfere with each other.
Luminescence microscopy. The method is based on the ability of certain substances to glow when exposed to short-wave radiation. In this case, the emitted light waves longer than the wave that causes the glow. In other words, fluorescent objects absorb light of one wavelength and emit in a different region of the spectrum. For example, if the inducing radiation is blue, then the resulting glow can be red or yellow. These substances (fluorescein isocyanate, acridine orange, rhodamine, etc.) are used as fluorescent dyes to observe fluorescent (luminescent) objects. In a fluorescent microscope, light from a source (ultra-high pressure mercury lamp) passes through two filters. The first (blue) filter blocks light in front of the sample and transmits light of the wavelength that excites the fluorescence of the sample. The second (yellow) traps blue light, but transmits yellow, red, green light emitted by a fluorescent object and perceived by the eye. Usually the microorganisms under study are stained directly or with AT or lectins labeled with fluorochromes. The drugs interact with Ag or other ligand-binding structures of the object. Luminescence microscopy has found wide application for visualizing the results of immunochemical reactions based on the specific interaction of AT labeled with fluorescent dyes with Ar of the studied object.
If you look into any real or virtual store of educational toys, then among the many products you will certainly find children's microscopes... It seems that the fashion for them arose quite recently, in the era of total "development" of children almost from the cradle. But it is not so. Such toys were known back in the 18th century. Then they were called "flea glasses". Into the bright cardboard tube about 2 cm long, a biconvex lens was inserted on one side, and a flat glass with an object attached to it, on the other. For example, a flea (hence the "flea glass"). Such toys were inexpensive and very popular. Modern kids microscopes are also very popular.
Why does a baby need a microscope?
It is very difficult to find those among preschoolers who are not interested in the structure of all life on Earth. Every day, children ask dozens of the most difficult questions to their mothers and fathers. Curious kids are definitely interested in everything: what animals and plants are made of, how nettles burn, why some leaves are smooth, while others are fluffy, like a grasshopper chirping, why a tomato is red and a cucumber is green. And exactly microscope will give an opportunity to find answers to many children's "why". It is much more interesting not just to listen to my mother's story about some kind of cells, but to look at these cells with my own eyes. It's hard to even imagine how breathtaking pictures can be seen through the eyepiece. microscope what amazing discoveries your little natural scientist will make. Classes with microscope will help baby expand knowledge about the world around them, create the necessary conditions for cognitive activity, experimentation, systematic observation of all kinds of living and non-living objects. The baby will develop curiosity, interest in the phenomena happening around him. He will pose questions and independently seek answers to them. A little researcher will be able to look completely differently at the simplest things, see their beauty and uniqueness. All this will become a solid foundation for further development and learning. It should be noted that the interest of one of the adults is very important: mom, dad, older brother or sister. Then they can convey their passion baby... The little one himself, unless, of course, he is a born biologist, is unlikely to bother with microscope without your active help and participation.What are they
Child microscope is not fundamentally different from microscope biological. This is not a model or a toy, but a working optical device. And, often, such microscopes have very decent optics and high magnification. Let's take a look at the types of microscopes and try to identify their main pros and cons. So, most often in the store you will find the so-called direct biological microscope (monocular, i.e. having one eyepiece). Any of us came across a similar device in school biology lessons. This is the classic version microscope, only it is decorated in an unusual and fun way to please its little owner (can be painted in bright colours or have an unusual shape). It can be used to view both transparent objects (on glass slides in transmitted light) and opaque (in reflected light). Important characteristic any microscope- its increase. Usually microscopes have three interchangeable lenses. But it is not only the lens that magnifies. The eyepiece also has its own magnification (usually 10 or 20 times). To calculate the total increase microscope, you need to multiply the eyepiece magnification (always written on the eyepiece) by the lens magnification. So if microscope has an eyepiece with 20x magnification and objectives of 4, 10 and 40, when changing lenses we get 80x, 200x and 800x magnifications. Modern lighting microscopes can create an increase of 1500-3000 times. Is it worth buying a device with such an increase as the first microscope to kid preschooler? Probably not worth it. Even for very serious experiments baby it is unlikely that an increase of more than 400-600 times will be needed. Microbes, however, cannot be considered. But, if one of the parents does not have special education, you most likely will not see them in the "cool" microscope... To prepare a microbial preparation, you need to use special methods of staining a smear, very powerful lighting and immersion lenses (a lens with a high magnification is immersed in a special immersion oil, usually cedarwood, to eliminate light scattering). But there is no reason to be upset. And without microbes, a little biologist with a head will have enough objects to study. A very good choice for a baby will be stereomicroscope (binocular). It has two eyepieces at an angle to each other, which creates a stereo image. And although such microscopes give relatively small magnifications (up to 100), but they allow us to consider almost any objects that surround us. This will help baby see many ordinary things in a completely different light. For such microscope no need for powerful lighting. And above all else, binocular microscope evenly loads both eyes, which is more suitable for fragile children's vision than monoculars. Many modern microscopes have their own built-in backlight. Pay attention to this when choosing a device. An additional light source allows you to better illuminate the object, and, therefore, better see it. There are very small ones "Pocket" microscopes with a slight increase. You can carry them with you for a walk and look at plants and insects right in the meadow or in the forest. If you have a computer at home, you can get one digital microscope ... This expensive modern toy also has its advantages and disadvantages. The main advantage is the ability to display images on the monitor screen. It transforms microscope in the semblance of an exciting computer game. The child can save the resulting image, edit, color, sign using a simple graphic editor. You can also record video and even make your own video about the microworld. The microscope is removed from the stand, you can walk around the room with it, bringing it to any objects and getting an enlarged image on the screen. In a sense, such microscope transforms from a research device into a creative tool. Is it good? Yes and no. If your baby is a creative, digital nature microscope surely he will like it. If the crumb is more likely a natural scientist seeking to comprehend the secrets of the universe, it is better to acquire for him the usual microscope... All exciting essence microscope precisely in the fact that you look through the eyepiece. As if you look with one eye into the unknown and wonderful world, another universe ...We equip the laboratory
In order to practice with microscope not bored baby, organize them like addicting game adding a certain amount of mystery. Let be child imagine himself as a real scientist-researcher. And for this he will need a mini-laboratory. Highlight baby the shelf where it will stand microscope, stored samples and the necessary tools for children's research. Normal desk can turn into a work corner in a matter of minutes. Just take care of good lighting. This will reduce the inevitable strain on children's eyes: the more illuminated the subject, the easier it is to see it. So the best place for microscope- near the window. Add a bright desk lamp to that. Immediately teach your baby to maintain order in the workplace (there should always be order in the laboratory!), And after class to clean everything up. Give to kid all kinds of jars and boxes in which he can store his objects for research and the necessary inventory. Except for the microscope, you will need slides, coverslips, pipettes, tweezers, and a needle. And also some substances: distilled water, alcohol, an aqueous solution of iodine (for coloring). Explain baby safety rules and strictly enforce them. All the same microscope(even for children) is not a toy, but a complex optical device. And they shouldn't crack nuts. Also, it is not necessary to mindlessly twist all the screws in a row. This should be done consciously and with a specific purpose. Tell us right away baby, what and for what in the microscope is intended and teach the baby to call everything by their proper names, and not by "things" and "wheels". It has been noticed that even five-year-olds quickly learn to microscope: select the desired magnification and sharpen it, looking at everything that comes to hand. At first, do not leave your baby with microscope one on one. Your little microscopist will quickly learn to look at objects in reflected light at low magnification. But work with microscope slides is better not to trust him yet, but to do it together. First, the preparation of the drug involves the manipulation of sharp objects (blade, needle) and chemicals... Secondly, slides are extremely fragile. Inexperienced fingers can easily crush and injure them. Teach your baby to use tweezers: separate pieces of the objects under study, put them on the stage. This will develop the neatness and precision of the little explorer's movements.
Scientific expedition
Since the kid has turned into a natural scientist, then it's time to go on a scientific expedition for all kinds of samples. For such an unusual walk, you should stock up on several jars with lids and boxes, where you will put your finds. A box of chocolates with plastic cells or a plastic egg tray is very convenient for these purposes. You will also need a marker to label the sample boxes, tweezers, and a penknife. Each time you can organize "expeditions" to different places... Look for samples in the yard today, go to the meadow tomorrow, and the day after tomorrow to the reservoir. Give baby the ability to decide for himself what he wants to take home for study. And, of course, give him some ideas of yours. What can you collect? Everything! Leaves, flowers, petals, thorns of plants, seeds of trees and flowers. All kinds of soils: black soil, sand, clay. It is very interesting to consider with the baby the composition of black soil (the remains of plants and even living insects are clearly visible), grains of sand (beautiful round crystals) and viscous clay. It will immediately become clear where it is best for plants to grow and why. Collect several types of lichens. They are amazingly beautiful under microscope... It is interesting to look at the moss. You can often find tiny insects in it that are practically invisible to the naked eye. Break off a piece of bark from different trees. Bird feathers will come in handy. Scoop up a little water from a puddle and an overgrown reservoir, grab some algae and ooze. Sort all this booty and sign. Now your little biologist has enough work for a long time.Setting up the microscope
First of all, you need to set up the lighting. To do this, turn the mirror under the stage so that the light table lamp reflected from it and passed through the aperture of the diaphragm. While looking through the eyepiece, rotate the mirror until the entire field of view (ie, what you see through the eyepiece) is evenly illuminated. Now place your specimen on the stage and fix it with special holders. Install the lens with the lowest magnification. While looking through the eyepiece, use the adjustment screws to slowly raise or lower the viewing tube. microscope until an image of the preparation appears in the field of view. During focusing, you can gently move the drug. This will make it easier for you to position it correctly. After finding the image, rotate the screws even more slowly so that the object under study becomes as sharp as possible. Then, if necessary, set a higher magnification. Everything can be considered! If the microscope comes with a built-in illuminator, then you do not need a mirror. Also, there is no need to adjust it if you are going to view objects in reflected light. In this case, simply place the subject on the stage, which should be as illuminated as possible, and adjust the focus.
How to prepare the drug
In order to see any object in transmitted light, it must be very thin and transparent (otherwise the rays of light will not be able to pass through it). Wash the coverslips thoroughly, rinse in alcohol (to avoid stains) and dry. If you are going to test any liquid (such as milk, juice or water), simply put a couple of drops on a glass slide and cover with a cover slip. If the object of study is a piece of a plant, then using a sharp blade, cut off a thin, transparent film from it, take it with tweezers and place it in the center of the cover glass. Drop one drop of water on top. The baby can also drip water, but, of course, you have to work with the blade. If your object is transparent, you need to paint it by adding one drop of an aqueous solution of methylene blue (popularly known as "blue"). Now we cover all this with a cover glass, making sure that no air bubbles remain under it, blot the excess liquid and study under microscope... This drug is called temporary. After studying it, the glasses are washed and used for subsequent experiments. If you want to keep the preparation for a long time, before putting the cover slip, apply transparent glue along its edge with a thin needle, gently press down (the glasses are very fragile and easily crack!) And leave to dry for a day. It is now a permanent drug that can be treated many times. By the way, most microscopes come with ready-made microscope preparations and slides for examination. These kits can be purchased separately.What can you see?
For viewing under microscope literally everything works. Start with a small increase. Consider the leaves of the collected plants with the baby. Many of them have hairs that are very interesting to see in microscope... The structure of the leaf and veins are clearly visible. Look at the mother-and-stepmother leaf from one side and the other. They are completely different: one side is pubescent, the other is not. First, let the baby determine it by touch, and then see the hairs in microscope... On a nettle leaf, you can see the very stinging hairs that cause so much trouble to naked children's legs and arms. Tear off a piece of paper from each indoor plant... Each is interesting and unique in its own way. If cacti grow on the windowsill, let them sacrifice a few thorns for the sake of science. Flower petals are very beautiful. You can see the pollen. To do this, transfer it with a soft brush from the flower to a glass slide. If baby it will be interesting, try to sketch what the pollen looks like different plants... Some microscopes equipped with a special projector that projects an image onto paper. This will make it easier to sketch. Consider the skin and pulp of all kinds of vegetables and fruits. How are they similar and how are they different? It is interesting to look at the hair and compare it in color and thickness. It turns out that cat hair is thinner than human hair, and father's hair is thicker than children's hair. And slipped under microscope your own finger can make a splash. Particularly impressive is the dirt under the nails. Of course, you won't see microbes there. But even without them it looks terrifying. You may be asked to cut your nails right away. It is no less interesting to see what house dust consists of, what paper, cotton wool, threads, scraps of doll hair and fur look like. soft toys, fish scales and bones, eggs, honey, drops of milk, crystals of salt, sugar, citric acid, soda, ice, all kinds of seeds and cereals, pieces of mushrooms, pebbles and shells brought from the sea, cones, paper money (you can find different signs which are not visible without magnification). If you have an aquarium, scrape off some plaque from the sides, place it on a glass slide, cover it with a coverslip and view at medium magnification. Believe me, this is an amazing picture! From the swamp water, which the kid collected during the "expedition", an interesting micropreparation is also obtained. Although not microbes, but living, moving creatures. Fantastic! In addition to zooplankton, you can also see unicellular algae with flagella. Sometimes frog eggs, tiny tadpoles and larvae of aquatic insects can get into the water. Then consider the tap water. Is there something alive and why? Grow mold on bread with your baby. To do this, put a slice of bread in a glass jar with a lid (if there is a special Petri dish, then in it), moisten it with water and put it in a warm place (but not in the sun) for several days. Place the slightly grown mold in a drop of water on a glass slide, cover with a coverslip, and your preparation is ready. Consider regular baker's yeast. To do this, pinch off a small piece from the briquette and dissolve it in a drop of water. And you can also sprout a grain of wheat and watch every day what changes take place with it ...Great and terrible
Well, the most beautiful objects for children's research are, undoubtedly, insects. Where to get samples for examination is up to you. But I think you shouldn't catch and kill insects on purpose. Even for the sake of science. It is not necessary to make this approach the norm for the baby. Exceptions can be insects "harmful": fly, mosquito, cockroach, Colorado potato beetle. These "annoyances" can always be found in abundance. It is very interesting to consider under microscope(especially binocular) fly. Pay the baby's attention to the structure of her eyes, legs, wings. Look at the wing from both sides. From above, its structure is clearly visible, and from below you will see a very beautiful picture: iridescent brocade shades. In a mosquito, pay attention to the "biting" device - the proboscis. Look for a butterfly wing in the meadow. Under microscope pollen is visible on it. Examine the cobweb. There you can always find dead small insects. It's amazing how complex such tiny, inconspicuous creatures are. Read the book "The Extraordinary Adventures of Karik and Vali" by J. Larry with your baby. Probably, Karik and Valya saw insects almost the same - huge and terrifying.Exploring Cipollino
The microscope will help baby learn that all living things are made up of cells. Under microscope you can see not only the cell, but also examine its structure. To do this, together with your child, prepare a simple and visual preparation from the usual onions... Why onions? This plant has very large cells, and they are clearly visible at a relatively low magnification. So, cut the onion into several pieces and separate one juicy layer. Cut a small piece from it, and then separate a thin film from the concave side of the piece with tweezers. Drop distilled water onto a glass slide, put a film in it and gently straighten it with a needle. Then add a couple of drops of an aqueous solution of methylene blue or an aqueous solution of iodine. This should be done in order for the colorless cells to become stained and more visible. If you can find a red-purple onion, you do not need to add the dye. Cover the resulting "beauty" with a coverslip on top and blot the emerging liquid. Try looking at the drug first at low magnification and then at high magnification. Tell baby that both plants and animals are made up of tiny cells. Here they are visible in microscope like little bricks. Why were they called cells? This name was invented by the English botanist R. Hooke. Considering under microscope a cut of the cork, he noticed that it consists of "many boxes." He also called these "boxes" cameras and ... cells. Indeed, it seems that someone has drawn the onion film into the cells. At high magnification, the cell wall, nucleus, and vacuole are clearly visible. Explain baby that the cell wall is a septum, a wall between cells. It protects the cage and helps to maintain the desired shape. Thanks to the nucleus, the cell grows and multiplies. And inside the vacuole there is cell sap. The one that splashes in different sides and brings tears when we cut onions.Red? Green?
Ask your kid why vegetables and fruits are different colors... He will try to answer the question by inventing fantastic versions. Listen carefully to his suggestions, and then offer to find out for sure. For the experiment, you will need several slides, the pulp of all kinds of fruits (watermelon, grated carrots, tomatoes, red and green peppers, rowan berries, etc.), green leaves of plants. Put a few drops of water on a glass slide, place a little ripe tomato pulp there and split it with a needle. Cover with a coverslip and look underneath with your baby. microscope... You will be able to see inside the cells special red inclusions - plastids. It is they who give ripe vegetables and fruits red, yellow or Orange color... Green leaves and fruits also contain plastids, but green. And already familiar to us onions or potatoes are white because their plastids are colorless. Experiment with a wide variety of fruits and vegetables to make sure your baby is satisfied. And then tell him that plastids of one kind can turn into another. This is why a green tomato ripens and turns red. And what happens to green leaves in autumn, why do they turn yellow and red? I think that now the young biologist himself will be able to find the answer to this question. Well, isn't that wonderful? So let's summarize. The microscope is very exciting. Once ill with it, a little man can carry his love of research throughout his life. And whatever activity your grown son or daughter devotes themselves to in the future, these children's experiments will certainly serve them well. Interesting observations and amazing discoveries!Purchase of a children's microscope, which will allow the child to study with enthusiasm the world invisible to him, and receive answers to many questions of concern to him, of which, believe me, there will be a great many by this time.
Do not think that a children's microscope is just another toy, since in terms of its functionality it differs little from the simplest biological microscopes that are used in numerous laboratories, medical institutions and school rooms where children learn about the microcosm. Perhaps the only difference between the device for children is the appearance of the microscope, which can be painted in bright colors so that the baby immediately draws attention to this object and becomes interested in it.
When buying such a device, you need to understand that on this stage development of the child, he is unlikely to need a device that allows you to consider objects with the maximum possible magnification today. It is enough to buy an ordinary monocular microscope with several interchangeable objectives, which together with the eyepiece will give an increase of up to 800 carats, which will be quite enough for a young researcher to be able to see the structure of the objects under study.
Microscopes are often bought for children in order to interest them in nature and biology, however, it happens that the parents themselves are no less interested in looking into the microcosm than the child.
What can be seen through a microscope
1. Consider the leaves of the collected plants with the baby. Many of them have hairs that are very interesting to look at under a microscope. The structure of the leaf and veins are clearly visible. Look at the mother-and-stepmother leaf from one side and the other. They are completely different: one side is pubescent, the other is not. On a nettle leaf, you can see the very stinging hairs that cause so much trouble to naked children's legs and arms. Pull a leaf off each houseplant. Each is interesting and unique in its own way. If cacti grow on the windowsill, let them sacrifice a few thorns for the sake of science. Flower petals are very beautiful.
2. You can see the pollen. To do this, transfer it with a soft brush from the flower to a glass slide.
3. Consider the skin and pulp of all kinds of vegetables and fruits. How are they similar and how are they different?
4. It is interesting to look at the hair and compare it in color and thickness. It turns out that cat hair is thinner than human hair, and father's hair is thicker than children's hair.
5. Sliding your own finger under the microscope can make a splash. Particularly impressive is the dirt under the nails. Of course, you will not see microbes there. But even without them it looks terrifying. You may be asked to cut your nails right away.
6. It is no less interesting to see what house dust consists of, what paper, cotton wool, threads look like, scraps of doll hair and fur of soft toys, fish scales and bones, eggs, honey, drops of milk, crystals of salt, sugar, citric acid, soda, ice , all kinds of seeds and cereals, pieces of mushrooms, pebbles and shells brought from the sea, cones, paper money (on them you can find different signs that are not visible without magnification).
7. If you have an aquarium, scrape off some plaque from the sides, place it on a glass slide, cover it with a coverslip and view at medium magnification. Believe me, this is an amazing picture!
8. Grow mold on bread with your baby. To do this, put a slice of bread in a glass jar with a lid, moisten with water and put in a warm place (but not in the sun) for several days. Place the slightly grown mold in a drop of water on a glass slide, cover with a coverslip, and your preparation is ready.
Safety rules in the classroom with a microscope
In addition to the microscope itself, you will need slides and coverslips, pipettes, tweezers, and a needle. And also some substances: distilled water, alcohol, an aqueous solution of iodine (for coloring).
Explain the safety rules to your baby and strictly require them to be followed. After all, a microscope (even for children) is not a toy, but a complex optical instrument. And they shouldn't crack nuts.
Also, it is not necessary to mindlessly twist all the screws in a row. This should be done consciously and with a specific purpose. Immediately tell the kid what and for what is intended in the microscope and teach the baby to call everything by their proper names, and not by "things" and "wheels". It has been noticed that even five-year-old kids quickly get used to the microscope: they select the desired magnification and focus, examining everything that comes to hand.
At first, do not leave your baby alone with the microscope. Your little microscopist will quickly learn to look at objects in reflected light at low magnification.
But work with microscope slides is better not to trust him yet, but to do it together. First, preparation of a drug involves the manipulation of sharp objects (blade, needle) and chemicals. Secondly, slides are extremely fragile. Inexperienced fingers can easily crush and injure them.
Classes with a microscope will help the kid expand knowledge about the world around him, create the necessary conditions for cognitive activity, experimentation, systematic observation of all kinds of living and non-living objects. The baby will develop curiosity, interest in the phenomena happening around him.
The world around us is amazingly diverse and multifaceted. Each person is interested to know how everything that surrounds him is arranged, and many of us strive to open the veil of the mystery of the microworld, which cannot be seen by persons unprepared and unarmed with special equipment. To broaden your horizons, learn a lot of new and interesting things and look at many everyday things from the other side, all the curious will be helped by such an entertaining device and tool for professional research as a microscope.
With the advent of a microscope in your home, you will find your own minilab, in which you can carry out your fascinating experiences and experiments.
What is the first thing worth considering under a microscope? Listed below are some interesting and interesting objects for research.
To examine in detail the fascinating microcosm, even a relatively inexpensive model of a biological microscope, Micromed S-11, is quite suitable.
Honey under the microscope
The microscope will help you make a conclusion about whether the honey that is stored in your kitchen is natural and with which you are saved on rainy evenings.
It is necessary to take a little honey, dissolve it in water and let it settle for a couple of days. After settling, you need to collect the sediment from the bottom of the jar with a pipette and transfer it to a glass slide. Observing the sediment under a microscope, in natural honey You will notice pollen. By the type of pollen, it is possible to determine from which plants the honey was collected by the bees.
Looking at honey through the eyepiece of a microscope, you can see glucose crystals that look like stars and needles. If, instead, you notice sugar crystals in the form of large particles, then you can conclude that honey is not natural.
You need to take half a glass of boiled warm water, pour a spoonful of sugar into it, stir and add a little baker's yeast from a bag. After a few minutes, take a drop of the solution and transfer it to a glass slide, place a cover glass on top and observe the object under study at medium and high magnification under lower light. Under the microscope, you will see cells of a round or elongated shape - this will be yeast. With close observation, you can notice how tiny buds periodically begin to grow on some cells - these are new yeast cells. They either break off from the mother's cells, or remain, forming small chains.
Onions are a classic of the genre. Many of us remember how at school we examined a preparation of onions under a microscope. Why onion? Because it has relatively large cells that are very clearly visible under a microscope even at low magnification. To prepare an onion micropreparation, you need to cut the onion into pieces and separate one layer. Cut a small piece from this layer, and then separate a thin film from the concave side of this piece of onion using tweezers. Then drip boiled water onto a glass slide, dip the film into it and gently straighten it with a needle. Then drop an aqueous solution of iodine onto the preparation (for staining colorless onion cells). The prepared object for study must be covered with a cover glass and blotted out the water that has come out. And now you can start researching the plant.
The objects presented above and many, many others will become your guides to the world of amazing microscopic research! The world that exists at the cellular level is now open to you, you just have to
For two years now, I have been observing the microcosm at home, and for a year now, I have been shooting it with a camera. During this time, I saw with my own eyes what blood cells look like, scales falling from the wings of butterflies, how a snail's heart beats. Of course, a lot could be learned from textbooks, video lectures and thematic sites. But at the same time there would be no feeling of presence, proximity to what is not visible naked eye... That these are not just words from a book, but personal experience... An experience that is available to everyone today.
What to buy
The theater begins with a coat rack, and micro photography begins with the purchase of equipment, and above all, a microscope. One of its main characteristics is the set of available magnifications, which are determined by the product of the eyepiece and objective magnifications.
Not every biological sample is good for viewing at high magnifications. This is due to the fact that the greater the magnification of the optical system, the shallower the depth of field. Consequently, the image of uneven surfaces of the preparation will be partially blurred. Therefore, it is important to have a set of objectives and eyepieces that allows observation with magnification from 10–20 to 900–1000 ×. Sometimes it is justified to achieve a magnification of 1500 × (eyepiece 15 and lens 100 ×). A larger increase is meaningless, since more small parts does not allow to see the wave nature of light.
The next important point is the type of eyepiece. How many eyes do you want to view the image with? Usually monocular, binocular and trinocular varieties are distinguished. In the case of a monocular, you will have to squint, tired of the eye during long-term observation. They look through the binocular with both eyes (it should not be confused with a stereomicroscope, which gives a three-dimensional image). For photographing and filming micro-objects, you will need a "third eye" - a nozzle for installing equipment. Many manufacturers produce special cameras for their microscope models, but you can also use ordinary camera by purchasing an adapter for it.
Observing at high magnifications requires good lighting due to the small aperture of the lenses. The light beam from the illuminator, converted in an optical device - a condenser, illuminates the preparation. Depending on the nature of the lighting, there are several observation methods, the most common of which are the bright and dark field methods. In the first, the simplest, familiar to many people from school, the drug is illuminated evenly from below. In this case, through the optically transparent parts of the preparation, light propagates into the lens, and in opaque parts it is absorbed and scattered. On a white background, a dark image is obtained, hence the name of the method. With a dark-field condenser, everything is different. The light beam leaving it has the shape of a cone, the rays do not enter the lens, but are scattered on an opaque preparation, including in the direction of the lens. As a result, on dark background a bright object is visible. This observation method is good for studying transparent low-contrast objects. Therefore, if you plan to expand the range of observation methods, it is worth choosing microscope models that provide for the installation of additional equipment: a dark field condenser, a dark field diaphragm, phase contrast devices, polarizers, etc.
Optical systems are not ideal: the passage of light through them is associated with image distortions - aberrations. Therefore, they try to make lenses and eyepieces in such a way as to eliminate these aberrations as much as possible. All this affects their final cost. For reasons of price and quality, it makes sense to buy plan-chromatic objectives for professional research. Strong lenses (with magnification, for example, 100 ×) have a numerical aperture greater than 1 when using immersion, high refractive index oil, glycerin solution (for the UV region), or just water. Therefore, if, in addition to "dry" lenses, you also take immersion lenses, you should take care of the immersion liquid in advance. Its refractive index must necessarily correspond to a particular lens.
Sometimes attention should be paid to the design of the stage and handles to control it. It is worth choosing the type of illuminator, which can be either an ordinary incandescent lamp or an LED, which is brighter and less heated. Microscopes also have individual characteristics. Each additional option is an addition to the price, so the choice of a model and a complete set remains with the consumer.
Today, inexpensive microscopes for children, monoculars with a small set of objectives and modest parameters are often bought. They can serve as a good starting point not only for the study of the microcosm, but also for acquaintance with the basic principles of the microscope. After that, the child should already buy a more serious device.
How to watch
You can buy far from cheap sets of ready-made drugs, but then the feeling of personal participation in the study will not be so bright, and they will get bored sooner or later. Therefore, you should take care of both objects for observation, and about available means for preparation of preparations.
Observation in transmitted light assumes that the object under study is thin enough. Even the peel of a berry or fruit is too thick, so sections are examined in microscopy. At home, they are made with regular razor blades. In order not to crush the peel, it is placed between the pieces of cork or embedded in paraffin. With a certain skill, you can achieve a cut thickness of several cell layers, and ideally, you should work with a monocellular layer of tissue - several layers of cells create a fuzzy messy image.
The test preparation is placed on a glass slide and, if necessary, covered with a coverslip. You can buy glasses at a medical equipment store. If the drug does not adhere well to the glass, it is fixed by slightly moistening with water, immersion oil or glycerin. Not every drug immediately reveals its structure, sometimes it needs to be "helped" by touching up its shaped elements: nuclei, cytoplasm, organelles. Iodine and "green" are good dyes. Iodine is a fairly versatile dye; it can be used to stain a wide range of biological preparations.
When going out into nature, you should stock up on jars for collecting water from the nearest reservoir and small bags for leaves, dried insect residues, etc.
What to watch
The microscope has been purchased, the instruments have been purchased - it's time to start. And you should start with the most accessible - for example, onion peel. Thin in itself, tinted with iodine, it discovers clearly distinguishable cell nuclei in its structure. This experience, well known from school, is worth doing first. Pour the onion peel with iodine for 10-15 minutes, then rinse under running water.
In addition, iodine can be used to color potatoes. The slice must be made as thin as possible. Literally 5-10 minutes of its stay in iodine will reveal starch layers, which will turn blue.
A large number of corpses of flying insects often accumulate on the balconies. Take your time to get rid of them: they can serve as valuable research material. As you can see from the photos, you will find that there are hairs on the wings of the insects that protect them from getting wet. The high surface tension of the water does not allow the drop to "fall" through the hairs and touch the wing.
If you have ever touched the wing of a butterfly or a moth, you probably noticed that some kind of "dust" is flying off it. The pictures clearly show that this is not dust, but scales from the wings. They have different shape and come off quite easily.
In addition, using a microscope, you can study the structure of the limbs of insects and spiders, consider, for example, chitinous films on the back of a cockroach. And with proper magnification, make sure that such films consist of tightly fitting (possibly fused) scales.
An equally interesting object for observation is the peel of berries and fruits. However, either its cellular structure may be indistinguishable, or its thickness will not allow for a clear image. One way or another, you have to make a lot of attempts before it works. good drug: iterate over different varieties grapes to find one in which the coloring matter of the peel would have interesting shape, or make several slices of the plum skin, achieving a monocellular layer. In any case, the reward for the work done will be worthy.
Grass, algae, and leaves are even more accessible for research. But, despite their ubiquity, choosing and preparing a good drug from them can be difficult. The most interesting thing about greenery is, perhaps, chloroplasts. Therefore, the cut must be extremely thin.
Acceptable thickness often have green algae found in any open water. There you can also find floating algae and microscopic aquatic life - snail fry, daphnia, amoeba, cyclops and slippers. A small baby snail, optically transparent, allows you to see your heartbeat.
Your own researcher
After studying simple and affordable drugs, you will want to complicate the observation technique and expand the class of objects under study. For this, you will need both special literature, and specialized means, their own for each type of object, but still possessing some universality. For example, the Gram staining method, when different types of bacteria begin to differ in color, can be applied to other, non-bacterial, cells. The method of staining blood smears according to Romanovsky is also close to it. On sale there is both a ready-made liquid dye and a powder consisting of its components - azure and eosin. You can buy them in specialized stores or order them online. If you cannot get the dye, you can ask the laboratory assistant who does you a blood test at the clinic for a glass with a stained smear of her.
Continuing the topic of blood tests, we should mention the Goryaev chamber - a device for counting the number of blood cells and assessing their size. Methods for the study of blood and other fluids using the Goryaev chamber are described in the special literature.
V modern world where a variety of technical means and devices are within walking distance, everyone decides for himself what to spend his money on. It can be an expensive laptop or TV with an incredible diagonal size. There are also those who take their gaze from the screens and direct it far into space, acquiring a telescope. Microscopy can become an interesting hobby, and for some, even an art, a means of self-expression. Looking through the eyepiece of a microscope, they penetrate deeply into the nature, a part of which we ourselves are.
"Science and Life" about micro photography:
Microscope "Analit" - 1987, No. 1.
Oshanin S.L. With a microscope by the pond. - 1988, No. 8.
Oshanin S.L. Life invisible to the world. - 1989, no. 6.
Miloslavsky V. Yu. Home photomicrograph. - 1998, No. 1.
Mologina N.