MicrobeHunter.com

The hemocytometer (counting chamber)

The hemocytometer (or haemocytometer or counting chamber) is a specimen slide which is used to determine the concentration of cells in a liquid sample. It is frequently used to determine the concentration of blood cells (hence the name "hemo-") but also the concentration of sperm cells in a sample.

How to obtain the best resolution with your microscope

The resolution that a microscope is capable of achieving is probably the single most important factor that determines the quality of a microscopic image. Without a sufficiently high resolution, magnification is not possible without loss of quality. Read the following introductory post: . There are a variety of different factors that determine the achievable resolution. [...]

Cover glass thickness and resolution

The thickness of the cover glass can have a significant impact on the resolution. The effect is highest with high-numeric aperture aperture (high magnification) objectives, and barely noticeable when using objectives of a low numeric aperture. Types of cover glasses Cover glasses come in all sorts of different sizes. I already wrote a post about [...]

Answering reader questions

And yet again it’s time to answer some reader questions What are the things that all types of microscopes have in common? Microscopes can be very different (see . I therefore limit the answer to light microscopes. Things that optical microscopes have in common include: Objectives, Oculars/eyepieces, stage (carries specimens), light source, focusing system. Does [...]

How to make macro images

This time I’d like to talk about a topic which is only indirectly related to microscopy: macro imaging. Taking high-quality macro images can be quite a challenge and can involve quite a bit of trial and error until one has found the ideal conditions. The pictures of the rose have been taken with a Sigma [...]

Volvox

Volvox is a fresh water green algae and a member of the Chlorophyta. The picture shows a spherical volvox colony, each ball can contain hundreds, if not thousands of individual cells. The picture shows six daughter colonies inside the main colony. The main colony disintegrates and the daughter colonies are then released. Volvox is a [...]

Dandelion parachute ball up close

This is one of the first tries taking pictures with my new Sigma objective, and I have to admit that I’m very satisfied with the lens. The lens does not include image stabilization, a steady tripod is therefore a must. Contrast was slightly enhanced to make the background (my computer screen!) completely black. Mirror lock-up [...]

The effect of the mounting medium on specimen and image quality

The mounting medium can have a significant effect both on the image quality and on the specimen itself. I tried a little experiment by observing pollen from a plant (in this case the buttercup, Ranunculus), mounted in five different ways: Air-mounted, with no cover glass Air-mounted, with a cover glass Mounted in water (temporary mount) [...]

Q & A: What people searched for

In this post I’d like to address some of the search queries that people typed to find this web site. Naturally people typed many, many more search queries, most of the queries are made of 1 or 2 words. I selected the longer ones for this post. Q: What is the principal advantage of an [...]

Ranunculus (Buttercup) pollen

Spring time is pollen time! Here are two images of Ranunculus repens (the Creeping Buttercup or Creeping Crowfoot) pollen, the top one in dark field, the bottom one in bright field. This plant is poisonous and can cause skin irritation. The name “Crowfoot” comes from the shape of the leaves, which resemble the claws of [...]

Common defects of old microscopes

During the past couple of years I've seen numerous microscopes that were is a desolate condition. Here are some of the problems that I observed. It may pay off to consider these problems when shopping for a used microscope.

Virtual microscope: Male flower of a pine tree (Pinus)

The male pine cone (or flower) is responsible for forming pollen. These pollen grains are also visible in the image above. For a zoom-able image of a female pine cone, visit the following link:

Virtual Microscope: Cross section of the earth worm (Lumbricus terrestris)

The image above shows Lumbricus terrestris, the earth worm, in cross section. The red part in the center is the digestive system. You can zoom into the image. The only adjustment done to the image was a color correction. The image was not sharpened.

Human hair under the microscope

Today I’d like to show you a nice microscopic picture, which I took several years ago of two human hair. The pictures on the right show you the original, unprocessed image at the top, and a second cleaned-up image with a nice background on the bottom. The top image shows darkened corers from the field [...]

Köhler illumination to reduce reflections

The Köhler (or Koehler or Kohler) field diaphragm is located above the light source. It is responsible for controlling the width of the light beam (but not its intensity). The light source of a microscope without Köhler illumination will illuminate the whole specimen, which may be the source of stray light and excessive heating of [...]

5 Rules of buying a microscope

I’ve been repeatedly asked for advice concerning the purchase of microscopes of hobby and amateur purposes. The following rules should help you in your choice. Rule 1: Be weary about “department store” microscopes Enthusiasts who want to pick up the hobby frequently encounter their first microscopes in department stores and toy shops. If you are [...]

Magazine articles on microscopy

Popular Science magazine published many different articles dealing with microscopy. These articles can be accessed over Google Books: Popular Science articles on microscopy. Even though some of the articles are quite dated (going back into the 1930s), they still can contain valuable information and tips which remain valid up to today. Be aware that not [...]

How to make microscope filters

Commercial microscope filters are usually made of stained glass. In the case of patch stops (as used in dark-field illumination), they may be made of aluminum. The dark-field patch stops block some of the light and the specimen will appear bright on dark background. The traditional way of DIY patch stops is cutting them out [...]

Stereo microscope projects

You’ve bought your kid a stereo microscope as a birthday present and now wonder what to look at. Or maybe you are teacher and want to give your class an introduction into (stereo) microscopy and need some specimens to look at (or maybe you bought yourself one, and now want to start out observing…) Requirements [...]

Bacteria in phase contrast

The four pictures on the right show different bacterial species in phase contrast. About phase contrast Bacteria are transparent and therefore difficult to see using regular bright-field microscopy. The bacterial cells will appear just as bright as the surounding medium and there is no color contrast. Phase contrast optics provides a solution. Phase contrast optics [...]

Trichinella spiralis – the “pork worm”

Trichinella spiralis is the smallest nematode parasite in humans. It causes the disease trichinosis. It is also one of the most wide spread parasites of the world. It can be contracted by eating raw or half-cooked pork or wild game animals. Life Cycle of Trichinella spiralis T. spiralis larva are encapsuled in the muscle of [...]

Digital methods for improving microscopic photographs

Digital photography gives the users many new possibilities in improving photographs taken through the microscope. This post gives an overview of the different image processing functions that can be applied to microscopic images. This post places a focus on what is possible, but does not explain the “how” part. This is something that I plan [...]

Observing bacteria under the light microscope

It is possible to use non-toxic stains (such as ink for fountain pens) to stain yogurt bacteria in-vivo.

Making a wet mount for microscopy

A wet mount (or temporary mount) is one of the most common ways of observing specimens under the microscope. The sample to be viewed floats in a layer of water which is between the slide and the cover glass. The water performs an important optical function. Without it, the resolution is lower. The general procedure [...]

Making mounts of pollen grains

Permanent slides of pollen grains can be used as a reference for identifying unknown pollen samples. It is therefore important, that the pollen grains remain in an authentic, natural shape. The preparation and mounting of the pollen can introduce artifacts: the pollen may lose some of its pigment, start to shrink and shrivel or absorb [...]

Required camera resolution for photography through the microscope

My digital camera (a Canon EOS 450d) is capable of taking pictures at 3MP, 6 MP and 12 MP (MP=megapixels). Which setting should one choose to obtain the optimum results? If the camera resolution is too low, then this will result in the loss of image detail (but a small file). A resolution setting which [...]

An overview of mounting media for microscopy

Mounting media are needed for making permanent slides. The mounting medium holds the specimens in place between the cover slip and the slide. The choice of the right mounting medium is a separate topic all on its own. There are countless commercial and home-made mounting media available. Which ones should one use? In many cases [...]

Choosing the right mounting medium for making permanent slides

There are numerous different mounting media available for making permanent slides. What factors determine the choice of the mounting medium? Here are some possible points to consider. Toxicity: Solvent-based mounting media (such as Eukitt and Canada Balsam) require the specimen to be in xylene prior to embedding. This substance is toxic. Other mounting media, such [...]

Different types of microscopes

How many different types of microscopes are there? More than you probably thought. I tried to research a list of different types, based on the physical principle used to make an image. Of course, one could also classify the microscopes based on their area of application, their cost, their versatility or any other aspect. These [...]

Taking stable photographs with a microscope

Specimens which are suspended in water are not completely immobilized. Small objects will start to vibrate when one is tapping on the table on which the microscope stands. The optics of the microscope will magnify even the smallest vibrations. These vibrations become problematic when taking pictures with a photo camera which is mounted directly to [...]

Staining bacteria

Here is yet another link to an article from Popular Science magazine. It deals with the isolation, fixing and staining of bacteria. I would not recommend the use of some of the solvents that they use (such as xylol) with children, however. They also describe a blood smear preparation, what I do not recommend for [...]

Virtual microscope: dandelion parachute

This the the parachute of a dandelion seed. The seed is not shown, it is attached to the long extension on the right. The leaves of the plant are toothed. The name “dandelion” comes from the French “dent-de-lion” meaning “lion’s tooth”. The microscopic observation reveals that the leaves are not the only part of the [...]

Virtual microscope: The Tick

This is a darkfield image of a tick. Ticks are blood-sucking arthropods. They possess 8 legs and are not insects, but rather are related to the spiders. Ticks are known to transmit various diseases, such as Lyme’s disease and encephalitis. For more information on the tick, read the following post: .

Stains and reagents for microscopy

I found an article in Popular Science Magazine (see link below) which gives a general overview of different stains that can be used in microscopy. The article divides the stains into three categories: Common household chemicals: this includes Iodine, for example. They are very readily available. Substances used mostly for microscopy: Methylene blue, Hematoxyline, and [...]

Virtual microscope: maple leaf skeleton

This is a scan of maple leaf vascular tissue, done with a normal flat-bed scanner. Method: Preparing the leaf was the difficult and time-consuming part. The leaf was boiled for several hours until the cells started to separate. I then carefully lifted the leaf out of the pot and placed it on a plate with [...]

Virtual microscope: female pine cone (Pinus)

For more information on the pine cone, have a look at the following post: The specimen size is approximately 20mm from left to right.

Virtual microscope: Aristolochia sipho

If you can not see anything, then you need to install a flash player. The image shows the cross section of the stem of the Aristolochia sipho plant. The image is an inverted (negative) image, and not a dark-field image. Why did I choose to invert the colors? The reason is surprisingly unscientific: it simply [...]

Digitizing photographic slides with a digital camera

Several years ago, at a time when digital single-lens reflex (SLR) cameras were still financially unobtainable, I used slide film to document my microscopic observations. These slides are now sitting, more or less nicely sorted, in a folder, doing pretty much nothing. I don’t even have a slide projector to look at them. Evidently the [...]

Dirty microscope objective: Its effect on image quality

The microscopes in the school where I work have been in operation almost 30 years (!!) now. And the fact that most of them have remained usable says quite something about the quality of these devices. They are soon going to be collectively sent in for maintenance, and this is the last opportunity to do [...]

What in the world is microbe hunting?

A quick Google search of the term “microbe hunting” revealed 2460 hits, the term “microbe hunter” a mere 21300 hits. The combination of these words with “amateur microscopy” returned a total of… 1 and 4 hits respectively. This is not much. The one returned hit is particularly interesting. It is from Popular Science, September 1934, [...]

Mitosis stages of the Lily

Mitosis stages of the lily flower. The chromosomes are well visible.

Buttercup (Ranunculus repens) Root

Vascular tissue of a Buttercup, Ranunculus, root.

The Tick (Ixodidae)

A tick in dark field. Ticks are parasites that feed on blood. They are known to transmit a variety of diseases, such as Lyme disease (borreliosis) and tick-borne encephalitis.

Advantages of LED Microscopes

Light emitting diodes are a nearly ideal microscopic light source for several reasons. A school should seriously consider purchasing these. Long life span: LEDs have a life span of approximately 50 000-100 000 hours. A microscope which is in operation an unrealistic 12 hours per day would have a life span of 20 years+. Unlike [...]

What features are not necessary for schools?

Microscopes have a large price span, ranging from cheap to in-affordable. Especially in an educational setting, money may play an important factor - money which should be well spent, and maybe not even spent at all on unnecessary microscope features.

Introductory Microscopy Projects for Schools

Are you looking for simple microscopy projects for classrooms? Here is a list of ideas. Do not forget about safety measures!

Introducing the Microscope

Introducing the Microscope Videos - Parts 1 to 3

Microscope Slides and Cover Glasses

This post gives an overview over common microscope slides and cover glass standards.

Timeline of Microscopy

The development and history of the optical microscope was one which stretched over a long period of time with many larger and smaller contributions. The following list highlights some of these milestones.

The Dog Flea (Ctenocephalides canis)

The Dog Flea (Ctenocephalides canis) is an external parasite which can be found in the fur of both dogs and cats. The adult female flea reaches a size between 2 and 4mm. Males are a little smaller, 2-3mm.

Papaya (Carica papaya) in Polarized Light

A piece of papaya was squeezed between the microscope slide and cover glass. The sample was observed in polarized light.

Increasing Contrast using Optical Methods

Many microscopic specimens are either very thin or transparent or lack color. They lack contrast and can not be easily seen in bright microscope light. In many cases it is not possible or desirable to chemically stain the specimens. In this case, optical techniques become necessary to enhance contrast.

Making a Soil Culture for Growing Algae

It may be necessary to grow large amounts of green algae (and other microorganisms) to be used for microscopic observations in schools. A soil culture allows you to enrich various types of algae.

Wood of the Spruce Tree (Picea)

The wood of a spruce tree (whitewood) under the microscope. The annual rings are clearly visible.

Spirogyra Algae

Microscopic picture of the algae Spirogyra. The algae possesses a spiral shaped chloroplast, which is clearly visible in the cell.

Vitamin C (Ascorbic Acid) Crystals

Both images depict Vitamin C (Ascorbic Acid) crystals under low magnification using crossed polarizing filters.

Sand from the Kalahari Desert

Sand from the Kalahari desert under the microscope. Dark field illumination.

Electron Microscopes vs. Optical (Light) microscopes

This post outlines the advantages and disadvantages of electron microscopes in contrast to optical (light) microscopes. Each type of microscope is designed for different areas of applications.

Elderberry (Sambucus)

Microscopic image of the cross section through the stem of an elder plant (Sambucus)

Shaving Foam

Shaving foam under the microscope. Dark field illumination.

Observing Potato Starch Grains

Potato starch grains are an ideal for observation in polarized light and in dark-field. Sample preparation is simple and straight-forward.

Potato Stach Grains

Here I would like to show you two images of potato starch grains taken with different optical contrasting methods.

Female Pine Cone (Pinus)

Microscopic image of a female pine cone (Pinius).

Some histology: Human Scalp (Head skin)

We now have a look at a microscopic image of human head skin (scalp) with hair roots.

Kiwifruit Mystery

Click on Observing a kiwi fruit to read the procedure.

Root of a Monocot

The image shows a cross-section of Zea mays, maize, a monocotyledonous plant ("monocot"). Epidermis, endodermis and vascular tissue is clearly visible. This is another panorama photomicrograph, assembled from four individual images.

Hydra, a fresh-water polyp

Hydra, a fresh-water polyp.

Head of a Fly

Microscoic image of the head of a fly, several pictures combined to one.

Drawing Microscopic Images

Drawing is still a useful method for documenting microscopic specimens, despite advances in (digital) imaging technologies. There are certain advantages in drawings that photographs do not possess.

Dry-mounted permanent slides

Wings of insects, small insects and other small specimens do not have to be enclosed in a mounting-medium, they can also be dry-mounted. If they are completely dry, then they will also store for a long time.

Processing Specimens for Microscopy

Not all microscopic specimens can be observed directly with a compound microscope, many of them need to be brought into a form which is suitable for observation. Different specimens have to be processed differently. This article gives an overview of different preparation methods.

Observing a Kiwifruit

Soft specimens can be observed by squashing a small sample between the slide and the cover glass. Here I would like to present: a Kiwi fruit

Mystery Object in Dust (Anthrenus sp.)

Anthrenus sp. is also known as a "carpet beetle", and is known to eat textile material. Not a good thing to have it around in a household.

Glossary of microscope terms

This post is a summary of relevant microscopy-related terms.

Fructose Mounting Medium for Permanent Slides

Many mounting media for making permanent microscope slides include organic solvents and are less suitable for the use in classrooms, at home and with children. In this article I would like to show you how to make fructose syrup to be used as a safe mounting medium.

Parts of a Compound Microscope

Here is a quick overview of the most important parts of a compound microscope (biological microscope) and their function.

Enhancing Photomicrographs

There are a range of different possibilities: Enhancing contrast: Photo editing software (such as Adobe Photoshop or GIMP) contain functions that enhance the contrast of an image. Find the menu point “Auto Levels” or simply “Levels”. This tool will make the darkest part of the image black (even if it was not black before) and [...]

Observing Brownian Motion

Brownian motion is the random movement of particles. It is possible to observe this movement under the microscope.

Staining Yogurt Bacteria

School microscopes are often not equipped with phase contrast optics, which would be suitable for viewing bacteria. It is possible to see bacteria also in regular bright field, but the results are better if they are stained. Yogurt bacteria are safe for the use in schools.

Some Safety Issues

Here are some safety issues to consider when doing microscopy lab work. This is not a comprehensive list.

Oblique Illumination

Oblique illumination is a contrast enhancing technique which can be realized with the use of home-made filters (patch stops) placed into the filter holder of the microscope condenser.

Darkfield Microscopy

Darkfield microscopy is one of the simplest and cheapest contrast enhancing techniques. It works well for specimens that have a refractive index which is different from its surrounding medium, but which are difficult to see because they lack color. Dark field microscopy shows the specimen bright on a dark background.

Types of Light Microscopes

This article outlines some similarities and differences between compound and stereo microscopes. They have different, but sometimes overlapping, areas of application.

Observing Leaf Stomata

It is possible to observe the impression of leaf epidermis cells on white wood glue. The stomata and guard cells are easily visible. The regular shape of the stomata makes it an ideal specimen for practicing drawing.

Working with the condenser aperture diaphragm

The condenser aperture diaphragm (or iris diaphragm) is used to control the contrast and resolution of an image. This article explains the usage of the diaphragm.

What accessories should be bought?

There are several accessories that are part of a microscopic workplace.

Changing the Lamp

This article explains how the lamp of a microscope is exchanged. It may not apply to all microscope types.

Cleaning the Microscope

What are some of the things to look out for when cleaning the microscope? What solvents should or should not be used? This article gives an overview.

Adjusting Koehler Illumination

Koehler illumination ensures that the specimen receives a bright uniform light. Only those areas actually seen are illuminated.

Advantages of Koehler Illumination

Koehler illumination offers a range of advantages over "critical illumination". Illumination is more uniform, specimen heating is reduced as well as light reflections for photographic work.

The Condenser Aperture Diaphragm

In this post, the function of the condenser aperture diaphragm is explained. The purpose of the condenser is to concentrate the light onto the specimen, its diaphragm regulates resolution, contrast and depth of field.

Simple Polarization Microscopy

It is not necessary to purchase a dedicated polarizing microscope to observe specimens in polarized light. A pair of linear polarizing filters is enough.

Observing Plasmolysis

It is possible to observe the plasmolysis of cells under the microscope. When salt water is added to onion cells, then the cells will lose water due to osmosis, this can be observed.

About the numbers on the Objective

This post explains the meaning of the different engravings on an objective.

Common Beginners’ Mistakes

The following section outlines some of the common beginners' mistakes when operating a microscope. Teachers are advised to instruct their students appropriately, proper microscope technique will not only enhance the image quality but will also lengthen the life-span of the microscopes.

Buying used Microscopes – a checklist

Used microscopes can be a good investment, provided that one is aware of a range of different issues.

Which Microscope for Children?

Which type of microscope to buy for children? The answer, in my view, is simple: the younger the child, the more you should trend towards stereo/binocular microscopes.

Determine Cell Size with a Slide Projector

This is one of my favorite lab activities. Onion cells are visualized using a slide projector. Using an internal reference mark, the students can calculate the actual size of onion cells. It does not require the use of microscopic equipment and can be conducted in the normal classroom (lab not required).

Making a Hay Infusion

It is possible to enrich microorganisms such as ciliates by making a hay infusion.

Growing Paramecia

Paramecia are fresh-water ciliates that make excellent microscopic specimens. They are relatively large and therefore easily observable, even under low magnification. Pond water usually does not contain sufficiently high concentrations of them. For educational purposes it is necessary to enrich them.