English photomicrographer Spike (M.I.) Walker has been a consistent winner of the Small World competition for many years, having won a total of 10 prizes and two honorable mentions. Presented in this gallery is a collection of images representing a cross-section of Walker's portfolio. Use the individual links for navigation to photomicrographs of interest.

Rotifer (Synchaeta grandis) - Captured with differential interference contrast optics, this living rotifer was photographed during a field course. Discovered in the late 1600s by Antoni van Leeuwenhoek, rotifers were originally called "wheel animalcules" or wheel animals because their coronas look like turning wheels. This appearance is caused by rippling (metachronal) waves of tiny beating cilia that draw food into their mouths and provide a means of locomotion.

Mixed Diatoms - An arranged group of diatoms is visualized with polarizing interference optics to produce this Jamin-Lebedeff image. Diatoms are single-celled algae of the phylum Bacillariophyta and are found in all the Earth's oceans. One of the most prolific sea organisms, the nearly 16,000 species of this group form a significant portion of the aquatic food chain. Diatom cell walls are composed of silica fashioned into a myriad of beautiful geometrical shapes and patterns. Diatomaceous earth, a substance composed of fossil diatoms, is used for making filters, insulation, abrasives, paints, and varnishes.

Desmid, (Micrasterias rotata) - This desmid specimen was taken from an almost pure culture in a flooded hoof print, which was also home to several frog tadpoles. Desmids are tiny aquatic organisms that display very striking symmetrical shapes as evidenced by the photomicrograph illustrated in this section. Seldom are two identical desmids found, because their bodies grow in a wide variety shapes and sizes. This specimen is a member of the Micrasterias truncata group, which displays two body halves joined at the center where the nucleus resides.

Vitamin C Crystallites - In preparing this specimen for photomicrography, Spike Walker altered the rate of crystalline growth fronts to produce a remarkable series of concentric patterns. He also utilized a technique termed "Spikeberg", a variation of Rheinberg illumination. Ascorbic acid, also known by the chemical name L-ascorbic acid, is a water-soluble vitamin that functions as a powerful antioxidant. Although most animals can synthesize vitamin C, others -- such as humans, other primates, and guinea pigs -- obtain it only through their diets. Vitamin C is commonly found naturally in peppers, citrus fruits, tomatoes, melons, broccoli, and green leafy vegetables such as spinach, turnip, and mustard greens.

Idoxuridine - A miniature crystal of the purified antiviral agent idoxuridine was recovered from a saturated aqueous solution and photographed under Rheinberg illumination. Known by the brand names Herpid (UK) and Herplex (USA & Canada), idoxuridine is a topically applied drug that is often effective against viral infections. Available as eye drops or ointment it is used to treat herpes simplex infections of the inner eyelids or the cornea of the eye. It is also prescribed for infections of the cornea caused by vaccines.

Diaminodiphenylmethane/Sulphur Complex - The two purified chemicals (diaminodiphenylmethane and sulphur) were mixed together on a microscope slide and melted under a cover glass. As soon as melting of all the constituents was complete, the cover glass was pressed down in order to reduce the thickness of the preparation and the slide quickly removed from the hotplate (an inverted electric iron is a good substitute). The specimen was photographed under crossed polarized illumination.

Amethystine Quartz Crystal - The surface of a facet in a amethystine quartz crystal was illuminated with reflected differential interference contrast optics and photographed on Ektachrome film. Most quartz samples are clear, but amethyst has a beautiful purple color due to small amounts of iron impurities in the crystal lattice.

Cyanobacterium (Gleotrichia echinulata) - This familiar fresh water cyanobacterium is found in lakes and reservoirs, where its pompon-like colonies can form thick blooms. The image was illuminated with ultraviolet fluorescence and photographed with a 25x plan apochromat objective coupled to an oil-immersion darkfield condenser.

Sulphur Crystals - A preparation of sulphur crystals (from the melt) was imaged between crossed polars with the assistance of a diffraction grating. A disk made from cleared base of Polachrome 35-millimeter film was placed at the back of a 4x/0.16 NA planapochromat objective to serve as the diffraction grating. The method is very time-consuming, and independent rotation of stage, polarizer/analyzer combination, and diffraction grating are useful if too much frustration is to be avoided.

Recrystallized Vitamin C - Beautiful cyan spherulites of vitamin C recrystallized from aqueous solution are revealed with striking red concentric ribbons spaced in almost equal intervals. The crystal growth front was selectively altered by Spike Walker during preparation of the specimen.

Calculi (Calcium Oxalate) - Calculi formed in the kidneys (stones, gravel or sand according to size) are usually composed of calcium oxalate, the smallest of which are commonly termed bladder sand. The photomicrograph, taken with polarized light and a full-wave retardation plate, reveals spherulitic structures reminiscent of those derived from single crystals.

Vitamin C "Tree Roots" - Recrystallized from a solution that was several days old, these micro crystallites of vitamin C resemble a pattern of tree roots. Actually, ordered rows of miniature spherulites are interspersed with ribbon-like crystals that are far less organized to render a surrealistic effect.

Water Flea (Daphnia) - A captivating photomicrograph of a daphnia (water flea) and its newborn is viewed with Rheinberg contrast illumination. Daphnia are microscopic crustaceans, belonging to the order Cladocera, that populate the quiet waters of lakes and ponds throughout the world. Most species are found in freshwater habitats, but a few occur in marine environments.

Etched Silicon Wafer - The underside of a silicon wafer, utilized in the manufacture of integrated circuits, was etched and photographed with reflected light under differential interference contrast (DIC) illumination. Silicon is an abundant element most commonly found in sand, as the oxide silicon dioxide. Before it can be made into an integrated circuit, the raw silicon material must be very pure. Silicon is refined from ordinary sand, Then melted and grown into ingots through a process that resembles dripping candles, which are 99.99999999 percent pure!

Crystals of Sulphur - A tiny amount of sulphur (several milligrams) was mixed with various organic compounds, including acetanilide and urea, and carefully melted under a cover glass. After melting, the preparation was quickly removed from the hotplate and the cover was pressed down firmly before any of the constituents could recrystallize (to reduce the thickness of the preparation).

Diatom (Actinoptychus) - The Actinoptychus specimen was photographed with a Metrimpex 3D condenser, a modified Abbe condenser of Hungarian manufacture, dating back to the early 1960s. Diatoms have a silicified cell wall forms a pillbox-like shell (frustule) composed of overlapping halves that contain intricate and delicate markings useful in testing the resolving power of microscope lenses. The beautiful symmetry and exquisite design of diatom frustules have gained them the title "jewel of the sea."

Carbon Composite - The carbon/carbon composite photomicrograph presented reveals numerous bundles of carbon fibers embedded in graphite. A photograph of this particular specimen was entered in a Polaroid photomicrographic competition, and Spike Walker was so impressed with the material that he explored microscopy on the original sample.

LycraŽ Fabric - A piece of LycraŽ was cut from a swim suit and pinned to a microscope slide for observation and photomicrography. What is revealed is a periodic set of fiber patterns typical of how textiles appear under the microscope. Originally developed as a replacement for rubber, LycraŽ is a man-made elastomeric fiber, invented and produced solely by DuPont. It is known for its ability to stretch up to six times its original length, then snap back to its starting size with no loss to its spring. Generically, these fibers are known as spandex in the United States and Canada, and as elastane in Europe.

Vitamin C Quilt Patterns - One of Spike Walker's most notable accomplishments in the field of polarized light microscopy is his ability to control the crystallization of vitamin C from evaporated aqueous solutions. The photomicrograph presented here is from a supersaturated solution placed on a microscope slide that was scratched into approximately 1.5-millimeter squares with a fine needle to provide 'windows' in which crystallization could proceed independently. The preparation was breathed on at 60-second intervals to alter the rate of crystal growth fronts.

Ciliate Protozoan - Filled with internal structural details, this phase contrast photomicrograph of Paramecium bursaria reveals a macronucleus with micronucleus in a notch, the protozoan's gullet, and two contractile vacuoles with radiating feeder canals. A living specimen of this ciliate protozoan was trapped under a cover glass and slightly compressed by carefully removing water from the edge of the cover with a strip of filter paper.

Freshwater Hydra - A male large brown freshwater hydra (Pelmatohydra oligactilis) is captured spreading its tentacles in search of prey. This species has a solid stalk and particularly long tentacles. The photomicrograph illustrates a profusion of testes and the large number of ectocommensal ciliate protozoa (Trichodina pediculus) which were gliding over the hydra's surface to give it a 'fuzzy' outline.

Onion Scale Epidermis - A small section of onion (Allium) bulb scale epidermis, obtained from a scale leaf, was taken from a red variety of onion and its outer epidermis stripped and mounted in water and covered. The photomicrograph was captured using differential interference contrast (DIC) illumination.

Thymolphthalein, Benzophenone, and Sulfur Complex - The three purified chemicals (thymolphthalein, benzophenone, and sulphur) were mixed together on a microscope slide and melted under a cover glass. As soon as melting of all the constituents was complete, the cover glass was pressed down in order to reduce the thickness of the preparation and the slide quickly removed from the hotplate (an inverted electric iron is a good substitute).

Candida albicans - This dimorphic fungus is the fungus that most often infects human beings. Normally, it lives on the mucosal membranes and the surface of the skin without causing harm, but can cause damaging infections when its population grows unchecked. In this case, the image features C. albicans in a thrush infection of vaginal epithelium from a fresh scrape preparation.

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