Micro World

Vitamin A

2008-11-30T10:51:00.000-08:00

Crystallized vitamin A

40x

Polarized Light

Stefan Eberhard

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=2005&imagepos=3

Doxorubin

2008-11-27T02:13:00.000-08:00

Doxorubin in methanol and dimethylbenzenesulfonic acid

80x

Polarized Light

Lars Bech

Polarized Light Microscopy

Welcome to our website devoted to the exciting field of polarized light microscopy. Our intent of this site is to provide you informative articles and information on equipment for use in polarized light microscopy. The petrographic microscope, as it is often called, is used to view rock and mineral specimens under polarized light. Birefringent specimens will exhibit stunning colorations when subjected to polarized light filters. When these filters are crossed under a condition called cross polarization (also called crossed nicols), characteristics of the mineral specimen can be compared to known characteristics in rock and mineral charts for an accurate identification of the rock or mineral.
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The components of a polarized microscope consist of a Bertrand lens, the first polarizing filter called a polarizer, a second polarizing filter called an analyzer, and various compensator plates. The three most common compensator plates are the quartz wedge, gypsum, and mica plates. It is advised to take a course in optical mineralogy such as would be given in a geology course to gain an indepth understanding of the principles of a petrographic microscope and its application of rock and mineral identification. If you have a need for a petrographic microscope for the study of polarized light microscopy, you are encouraged to contact us about our wide selection. We can provide monocular versions, binocular, as well as trinocular polarizing light geological microscopes.

Source

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=1996&imagepos=1

....

http://polarizedlightmicroscopy.com/.

2008-11-26T00:35:00.000-08:00

Inclusions of goethite and hematite in Brazilian agate

30x

John I. Koivula

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=1984&imagepos=1

Cell nuclei of the mouse colon

2008-11-25T02:55:00.000-08:00

Cell nuclei of the mouse colon

740x

2-photon fluorescence

Dr. Paul Appleton

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=2006&imagepos=1

?

2008-11-23T12:59:00.001-08:00

Scanning electron microscope image of a leaf from a Black Walnut tree. Image shows a cross-section of a cut leaf, itsupper epidermal layer, mesophyll layer with palisade cells and vascular bundles, and lower epidermal layer. The protrusion at center is just over 50 microns tall. (Dartmouth Electron Microscope Facility/Dartmouth College

http://www.boston.com/bigpicture/2008/11/peering_into_the_micro_world.html

Grains

2008-11-17T20:53:00.000-08:00

Pollen from a variety of common plants: sunflower, morning glory, hollyhock, lily, primrose and caster bean.

The largest one at center is nearly 100 microns wide.

(Dartmouth Electron Microscope Facility/Dartmouth College)

Pollen is a fine to coarse powder consisting of microgametophytes (pollen grains), which produce the male gametes (sperm cells) of seed plants. A hard coat covering the pollen grain protects the sperm cells during the process of their movement between the stamens of the flower to the pistil of the next flower.
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The structure of pollen
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Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell containing two nuclei: a tube nucleus (that produces the pollen tube) and a generative nucleus (that divides to form the two sperm cells). The group of cells is surrounded by a cellulose cell wall and a thick, tough outer wall made of sporopollenin.
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Pollen is produced in the microsporangium (contained in the anther of an angiosperm flower, male cone of a coniferous plant, or male cone of other seed plants). Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see Electron micrograph at top right). Most, but certainly not all, are spherical. Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the Forget-me-not (Myosotis spp.), is around 6 µm (0.006 mm) in diameter. Wind-borne pollen grains can be as large as about 90-100 µm.[
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The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archeology, and forensics.
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In angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of sporogenous cells form with in the anther, the fertile sporogenous cells are surrounded by layers of sterile cells that grow into the wall of the pollen sac, some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells. Four haploid microspores are produced from each diploid sporogenous cell called microsporocytes, after meiotic division. After the formation of the four microspores, which are contained by callose walls, the development of the pollen grain walls begins. The callose wall is broken down by an enzyme called callase and the freed pollen grains grow in size and develop their characteristic shape and form a resistant outer wall called the exine and an inner wall called the intine. The exine is made up of a resistant compound called sporopollenin; the intine is made up of cellulose and pectin. The exine is what is preserved in the fossil record.
Pollen grains may have furrows, the orientation of which (relative to the original tetrad of microspores) classify the pollen as colpate or sulcate. The number of furrows or pores helps classify the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus.
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Except in the case of some submerged aquatic plants, the mature pollen-grain has a double wall, a thin delicate wall of unaltered cellulose (the endospore or intine) and a tough outer cuticularized exospore or exine. The exine often bears spines or warts, or is variously sculptured, and the character of the markings is often of value for identifying genus, species, or even cultivar or individual. In some flowering plants, germination of the pollen grain often begins before it leaves the microsporangium, with the generative cell forming the two sperm cells.

http://en.wikipedia.org/wiki/Pollen

Snow Crystal

2008-11-15T13:18:00.001-08:00

Rime on a columnar snow crystal.

Contact between the snow crystal and the supercooled droplets in the air resulted in freezing of the liquid droplets onto the surface of the crystal.

Observations of snow crystals clearly show cloud droplets measuring up to 50 microns on the surface of the crystal.

(Agricultural Research Service, United States Department of Agriculture)

______________________________

A Snowflake Primer

... The basic facts about snowflakes and snow crystals ...

Snowflakes and snow crystals
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Snowflakes and snow crystals are made of ice, and pretty much nothing more. A snow crystal, as the name implies, is a single crystal of ice. A snowflake is a more general term; it can mean an individual snow crystal, or a few snow crystals stuck together, or large agglomerations of snow crystals that form "puff-balls" that float down from the clouds.
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The structure of crystalline ice
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The water molecules in an ice crystal form a hexagonal lattice, as shown at right (the two structures show different views of the same crystal). Each red ball represents an oxygen atom, while the grey sticks represent hydrogen atoms. There are two hydrogens for each oxygen, so the chemical formula is H2O. The six-fold symmetry of snow crystals ultimately derives from the six-fold symmetry of the ice crystal lattice.
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Snowflakes grow from water vapor
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Snowflakes are not frozen raindrops. Sometimes raindrops do freeze as they fall, but this is called sleet. Sleet particles don't have any of the elaborate and symmetrical patterning found in snow crystals. Snow crystals form when water vapor condenses directly into ice, which happens in the clouds. The patterns emerge as the crystals grow.
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The simplest snowflakes
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The most basic form of a snow crystal is a hexagonal prism, shown in several examples at right. This structure occurs because certain surfaces of the crystal, the facet surfaces, accumulate material very slowly (see Crystal Faceting for more details). A hexagonal prism includes two hexagonal "basal" faces and six rectangular "prism" faces, as shown in the figure. Note that a hexagonal prism can be plate-like or columnar, depending on which facet surfaces grow most quickly.
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When snow crystals are very small, they are mostly in the form of simple hexagonal prisms. But as they grow, branches sprout from the corners to make more complex shapes. Snowflake Branching describes how this happens.

The Morphology Diagram
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By growing snow crystals in the laboratory under controlled conditions, one finds that their shapes depend on the temperature and humidity. This behavior is summarized in the "morphology diagram," shown at left, which gives the crystal shape under different conditions. Click on the picture for a closer view. The morphology diagram tells us a great deal about what kinds of snow crystals form under what conditions. For example, we see that thin plates and stars grow around -2 C (28 F), while columns and slender needles appear near -5 C (23 F). Plates and stars again form near -15 C (5 F), and a combination of plates and columns are made around -30 C (-22 F). Furthermore, we see from the diagram that snow crystals tend to form simpler shapes when the humidity (supersaturation) is low, while more complex shapes at higher humidities. The most extreme shapes -- long needles around -5C and large, thin plates around -15C -- form when the humidity is especially high.
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Why snow crystal shapes change so much with temperature remains something of a scientific mystery. The growth depends on exactly how water vapor molecules are incorporated into the growing ice crystal, and the physics behind this is complex and not well understood. It is the subject of current research in my lab and elsewhere.
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The life of a snowflake
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The story of a snowflake begins with water vapor in the air. Evaporation from oceans, lakes, and rivers puts water vapor into the air, as does transpiration from plants. Even you, every time you exhale, put water vapor into the air. When you take a parcel of air and cool it down, at some point the water vapor it holds will begin to condense out. When this happens near the ground, the water may condense as dew on the grass. High above the ground, water vapor condenses onto dust particles in the air. It condenses into countless minute droplets, where each droplet contains at least one dust particle. A cloud is nothing more than a huge collection of these water droplets suspended in the air. In the winter, snow-forming clouds are still mostly made of liquid water droplets, even when the temperature is below freezing. The water is said to be supercooled, meaning simply that it is cooled below the freezing point. As the clouds gets colder, however, the droplets do start to freeze. This begins happening around -10 C (14 F), but it's a gradual process and the droplets don't all freeze at once. If a particular droplet freezes, it becomes a small particle of ice surrounded by the remaining liquid water droplets in the cloud. The ice grows as water vapor condenses onto its surface, forming a snowflake in the process. As the ice grows larger, the remaining water droplets slowly evaporate and put more water vapor into the air. Note what happens to the water -- it evaporates from the water droplets and goes into the air, and it comes out of the air as it condenses on the growing snow crystals. As the snow falls there is a net flow of water from the liquid state (cloud droplets) to the solid state (snowflakes). This rather complicated chain of events is how a cloud freezes.
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The rest of the story
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Alas, there's so much more to the story -- it simply cannot fit here on a single page. Snowflakes are fascinating objects (in my humble opinion), and you can learn all kinds of interesting things about them in The Snowflake: Winter's Secret Beauty. Click here to see what's inside this book.
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Very comprehensive site and beautiful photos of snow crystals
http://www.its.caltech.edu/~atomic/snowcrystals/primer/primer.htm

Source of image

http://www.boston.com/bigpicture/2008/11/peering_into_the_micro_world.html

2008-11-14T22:36:00.000-08:00

A polllen grain on perched on the anther of a Penta lanceolata flower.

The grain is about 40 microns wide.

(Dartmouth Electron Microscope Facility/Dartmouth College)

Electron Microscopy
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What are Electron Microscopes?

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Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale. This examination can yield the following information:
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Topography

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The surface features of an object or "how it looks", its texture; direct relation between these features and materials properties (hardness, reflectivity...etc.)

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Morphology

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The shape and size of the particles making up the object; direct relation between these structures and materials properties (ductility, strength, reactivity...etc.)

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Composition

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The elements and compounds that the object is composed of and the relative amounts of them; direct relationship between composition and materials properties (melting point, reactivity, hardness...etc.)
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Crystallographic Information

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How the atoms are arranged in the object; direct relation between these arrangements and materials properties (conductivity, electrical properties, strength...etc.)

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Where did Electron Microscopes Come From?

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Electron Microscopes were developed due to the limitations of Light Microscopes which are limited by the physics of light to 500x or 1000x magnification and a resolution of 0.2 micrometers. In the early 1930's this theoretical limit had been reached and there was a scientific desire to see the fine details of the interior structures of organic cells (nucleus, mitochondria...etc.). This required 10,000x plus magnification which was just not possible using Light Microscopes.The Transmission Electron Microscope (TEM) was the first type of Electron Microscope to be developed and is patterned exactly on the Light Transmission Microscope except that a focused beam of electrons is used instead of light to "see through" the specimen. It was developed by Max Knoll and Ernst Ruska in Germany in 1931.The first Scanning Electron Microscope (SEM) debuted in 1942 with the first commercial instruments around 1965. Its late development was due to the electronics involved in "scanning" the beam of electrons across the sample. An excellent article was just published in Scanning detailing the history of SEMs and I would encourage those interested to read it.

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How do Electron Microscopes Work?

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Electron Microscopes(EMs) function exactly as their optical counterparts except that they use a focused beam of electrons instead of light to "image" the specimen and gain information as to its structure and composition.The basic steps involved in all EMs:

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A stream of electrons is formed (by the Electron Source) and accelerated toward the specimen using a positive electrical potential.

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This stream is confined and focused using metal apertures and magnetic lenses into a thin, focused, monochromatic beam.

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This beam is focused onto the sample using a magnetic lens
Interactions occur inside the irradiated sample, affecting the electron beam .

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These interactions and effects are detected and transformed into an image. The above steps are carried out in all EMs regardless of type.

http://www.unl.edu/CMRAcfem/em.htm

Source of Image

http://www.boston.com/bigpicture/2008/11/peering_into_the_micro_world.html

Filamentous actin and microtubules

2008-11-14T03:42:00.000-08:00

Filamentous actin and microtubules in mouse fibroblasts

(1000x)

Dr. Torsten Wittmann

Actin is a globular, roughly 42-kDa protein found in all eukaryotic cells (except for nematode sperm) where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans. It is the monomeric subunit of microfilaments, one of the three major components of the cytoskeleton, and of thin filaments, which are part of the contractile apparatus in muscle cells. Thus, actin participates in many important cellular functions, including muscle contraction, cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape.

http://en.wikipedia.org/wiki/Actin

Source of Image

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=2003&imagepos=1

High Density Liquid Crystalline DNA

2008-11-13T23:41:00.000-08:00

The incredible play on color exhibited by this liquid crystalline DNA specimen is simply beautiful. Focal conic textures resembling fans form a unique pattern that shifts from purple to yellowish-orange in color. The DNA concentration for this specimen is approximately 400 milligrams per millimeter, and the magnification is approximately 375x. The digital image presented above was originally recorded on Fujichrome 64T transparency film using a Nikon Optiphot-Pol microscope with crossed polarized illumination. Exposures were recorded about 2.5 f-steps under the recommended value given by an in-camera photomultiplier and were push-processed approximately 1.5 f-steps in the first E-6 developer.

http://micro.magnet.fsu.edu/dna/pages/highdensity22.html

Fossil fusulinids in limestone

2008-11-12T22:08:00.000-08:00

Fossil fusulinids in limestone

Ron Sturm

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=1993&imagepos=1

Fossil Fusulinids

Fusulinids cover this limestone slab, collected from the Beil Limestone, Chautauqua County, Kansas.

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Description: Fusulinids were small, marine organisms that were common inhabitants of the world's seas during the Pennsylvanian and Permian Periods, from about 315 to 250 million years ago. The earliest fusulinids occur in rocks deposited during the late Mississippian Period, more than 320 million years ago. Fusulinids became extinct during the mass extinction at the end of the Permian Period, about 250 million years ago.

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Fusulinids were single-celled organisms, about the size and shape of a grain of wheat. Unlike multicellular animals, which accomplish basic life functions (such as locomotion, feeding, digestion, and reproduction) through a wide range of specialized cells, fusulinids and other single-celled organisms have to carry on these same functions within the confines of a single cell. As a result, the cell is highly complex.

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These Pennsylvanian fusulinids belong to the genus Triticites, which gets its name from the Latin word for wheat. Triticites is a common fossil in Kansas rocks.

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In fusulinids, this complexity is evident in the structure of the hard calcium carbonate shells, called tests. Internally, the tests, which are made up of calcium carbonate, are divided into a series of chambers. By studying living relatives of the fusulinids (a group called the foraminifera), scientists know that the tests were secreted by the protoplasm, the living material within the cell. As fusulinids grew, the test coiled around itself, adding chambers along its longitudinal axis.
This cutaway view of a fusulinid test shows the complex structure of these single-celled organisms. The prominent line on the outside of the text, the antetheca, was the growing surface, where new chambers were added (drawing by Roger B. Williams, KU Paleontological Institute).
The earliest fusulinids were minute, smaller than the head of a pin, and somewhat spherical in shape. During their 80 million years on earth, fusulinids evolved rapidly, typically becoming progressively longer and narrower. By the late Permian Period, some forms were over two inches long, an amazing size for a single-celled organism.
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As fusulinids evolved, the internal test walls also became increasingly complex, with more ornate subdivisions of their internal chambers. Fusulinids look fairly similar from the outside. In order to identify them, scientists usually examine a cross section of the fossil test under a microscope.
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Cross section of the common fusulinid Triticites, showing the distinctive internal structure of its chambers (drawing by Al Kamb, KU Natural History Museum, Invertebrate Paleontology).
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Because of their rapid evolution and their occurrence in the rocks from around the world, fusulinids are extremely useful in correlating the ages of sedimentary rocks from different parts of the earth. By matching the kinds of fusulinids contained within sedimentary rock formations, geologists can show that far-flung rock strata--as widely separated as Kansas and Russia--were deposited at approximately the same time.
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By studying the rocks in which fusulinids are found, geologists can determine what kind of environment they lived in. Apparently, fusulinids preferred a clear-water, offshore environment and may have been reef dwellers. The mass extinction at the end of the Permian Period decimated the world's reefs and their occupants.
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Fusulinid fossils are found on all continents except Antarctica and are common in the Permian and Pennsylvanian rocks of eastern Kansas. In fact, some Kansas limestones--for example, the Cottonwood Limestone Member of the Beattie Limestone, the Tarkio Limestone Member of the Zeandale Limestone, and the Americus Limestone Member of the Foraker Limestone--are made up almost exclusively of fusulinid fossils.
Stratigraphic Range: Upper Mississippian to Upper Permian.
Taxonomic Classification:Fusulinids belong to the Kingdom Protoctista, Phylum Protozoa, Order Foraminiferida, Suborder Fusulinina, Family Fusulinidae.
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Sources

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Buzas, Martin A., Douglass, Raymond C., and Smith, Charles C., 1987, Kingdom Protista; in, Fossil Invertebrates, R. S. Boardman, A. H.

Cheetham, and A. J. Rowell, eds.: Boston, Blackwell Scientific Publications, p. 67-106.
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Moore, Raymond C., Lalicker, Cecil G., and Fischer, Alfred G., 1952, Invertebrate Fossils: New York, McGraw-Hill Book Co., 766 p.
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Williams, Roger B., 1975, Ancient Life Found in Kansas Rocks--An Introduction to Common Kansas Fossils: Kansas Geological Survey, Educational Series 1, 42 p.
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Text by Liz Brosius, Kansas Geological Survey. Unless noted otherwise, illustrations by Jennifer Sims, Kansas Geological Survey

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=1993&imagepos=1

Pleurosigma

2008-11-12T10:17:00.000-08:00

Pleurosigma (marine diatoms)

200x

Michael Stringer

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=2008&imagepos=1

What is a diatom?Diatoms are aquatic, single-celled algae which possess a hard shell. They thrive in most fresh and salt water environments as long as some moisture is available. In the marine realm, diatoms along with coccolithophorids are the most abundant photosynthetic organisms.

Despite their prevalence, they're usually invisible because they're too small to be seen with the naked eye. They're so tiny that hundreds of them can fit on the head of a pin. Diatoms are usually between 2 and 200 microns in diameter. As with many small organisms, what they lack in size, they make up in numbers. During diatom blooms, the waters off California can change color due to sudden population explosions resulting in the growth of many hundreds of thousands of diatom cells per liter of seawater. What a crowd!
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Diatoms are considered phytoplankton. The term phytoplankton is used to refer collectively to all photosynthetic organisms that live by floating in seawater. "Phyto" refers to plant and "plankton" refers to a floating lifestyle. Despite their classification as phytoplankton, diatoms are technically not plants since they are single-celled rather than multicellular like plants.
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Diatoms are one of the most important photosynthetic organisms in the ocean.

http://earthguide.ucsd.edu/diatom/d2.html

Bryozoan statoblast

2008-11-11T21:11:00.000-08:00

Bryozoan Statoblast (diminutive aquatic animal of the phylum Bryozoa)

10x

Chiedozie Ukachukwu

Student at the Rochester Institute of Technology

Rochester, New York, USA

BRYOZOANS

Moss Animals
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Description
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Although inconspicuous and poorly known to most people, bryozoans are a major animal groups, having nearly 4,000 known species. Most bryozoans are marine, but a few dozen species live in freshwater habitats and a number these are known in South Dakota. They take the name Bryozoa (Latin for "moss animals") from their colonial and often 'furry' growth habit. Most colonies have a gelatinous matrix and form encrusting growths or branching colonies. They may grow on any submerged object, such as rocks, roots, and branches.
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The individual animals of a bryozoan colony are tiny, typically only 2 to 3 millimeters in length. Their most conspicuous feature is a retractable crown of hollow, ciliated tentacles, called the lophophore. T he lophophore serves in filter-feeding. Bryozoans feed on protozoans, bacteria, and organic matter from the water. In the center of the lophophore is the mouth, which marks the beginning of a U-shaped gut. The anus opens just outside the lophophore. The Bryozoa are sometimes classified as the Ectoprocta ('outer anus') to emphasize this feature.
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Bryozoan taxonomy is complex and depends largely on microscopic details. Identification is made easier because most freshwater species produce resistant bodies called statoblasts. These form in response to adverse environmental conditions. They contain a mass of cells enclosed in a bi-valved, hardened shell

http://www.northern.edu/natsource/INVERT1/Bryozo1.htm

Long nose potoroo

2008-11-09T13:17:00.000-08:00

Long-Nosed Potoroo (Potorours Tirdactylus)

Kidney epithelial cell

760x

Dr. Torsten Wittman

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=2002&imagepos=5

The Long-nosed Potoroo (Potorous tridactylus) is a species of Australian potoroo. Listed as Endangered in Victoria (Flora Fauna Guarantee Act 1988), Vulnerable in Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999), although the IUCN lists it as Lower Risk.

At first glance the Long-nosed Potoroo with its pointed nose and grey-brown fur looks very much like a

bandicoot — that is until it hops away with its front feet tucked into its chest; revealing its close relationship with the kangaroo family. It is only a small marsupial with a body length between 340mm and 380mm, and a tail length from 150mm to 240mm.[3]
As it is rarely seen in the wild, better indicators of its presence are the runways it makes through the undergrowth and the hollow diggings it leaves behind when feeding on underground roots and fungi.

http://en.wikipedia.org/wiki/Long-nosed_Potoroo

Vitamin C

2008-11-09T13:10:00.000-08:00

Vitamin C Crystals

125x

James Bell

http://www.nikonsmallworld.com/gallery.php?grouping=year&year=1978&imagepos=15

Vitamin C, also known as ascorbic acid, is probably one of the most highly publicized, yet least understood, of all of the vitamins. Championed by Nobel laureate Linus Pauling, Ph.D., and advocated by many nutrition buffs, vitamin C is indeed a fascinating and important nutrient (or micronutrient) necessary for human life.

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In this article, Dr. Jerry Gordon takes us on a fascinating tour of vitamin C, and shows why this vitamin is so important to your body!

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To understand vitamin C, we first need some information about vitamins in general. The word vitamin is derived from the combination of words: vital amine. Vitamins are organic (carbon containing) molecules that mainly function as catalysts for reactions within the body. A catalyst is a substance that allows a chemical reaction to occur using less energy and less time than it would take under normal conditions. If these catalysts are missing, as in a vitamin deficiency, normal body functions can break down and make a person susceptible to disease.
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Vitamins are required by the body in tiny amounts (hundredths of a gram in many cases). We get vitamins from three sources:
· Foods
· Beverages
· Our own bodies - vitamin K comes from bacteria within our intestines and vitamin D is produced with the help of ultraviolet radiation on the skin.
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Vitamins are either fat-soluble or water-soluble. The fat-soluble vitamins can be remembered with the mnemonic ADEK, for vitamin A, vitamin D, vitamin E, and vitamin K. These vitamins accumulate within the fat stores of the body and within the liver. Fat-soluble vitamins are often associated with toxicity when taken in large amounts. Water-soluble vitamins include vitamin C and the B vitamins. Water-soluble vitamins taken in excess are excreted in the urine and are not usually associated with toxicity. Both vitamin C and the B vitamins are also stored in the liver. It is interesting to note that most animals produce their own vitamin C. Man, primates (apes, chimps, et cetera) and guinea pigs have lost this ability. Due to this similarity with man, guinea pigs have been subjected to experimentation over the years.

http://www.howstuffworks.com/vitamin-c.htm