The Microorganisms gallery offers 172 images of microbiology and several types of microorganisms. Microorganisms, also known as microbes, are organisms that are microscopic, and are usually too small to be seen by the naked human eye.

"Pycnides of Peltigera rufescens. a, basidia; b, stylospores." —The Encyclopedia Britannica, 1910

Pycnides

"Pycnides of Peltigera rufescens. a, basidia; b, stylospores." —The Encyclopedia Britannica, 1910

A type of protozoa in the ocean.

Radiolarian

A type of protozoa in the ocean.

"Optical section of a Radiolarian. a, Nucleus; b, wall of central capsule; c, siliceous shell within nucleus; c1, middle shell within central capsule; c2, outer shell in extra-capsular substance. Four radial spicules hold the three spherical shells together." -Thomson, 1916

Radiolarian

"Optical section of a Radiolarian. a, Nucleus; b, wall of central capsule; c, siliceous shell within…

A modern Radiolarian, showing the skeletal structure of silica and the extended fleshy threads or pseudopodia.

Radiolarian

A modern Radiolarian, showing the skeletal structure of silica and the extended fleshy threads or pseudopodia.

<em>Heliosphaera echinoides</em>, a modern Radiolarian.

Radiolarian

Heliosphaera echinoides, a modern Radiolarian.

"A motile rodlet with one cilium and with a spore formed inside." &mdash; The Encyclopedia Britannica, 1910

Rodlet

"A motile rodlet with one cilium and with a spore formed inside." — The Encyclopedia Britannica,…

One group will take the spherical form and produce a shell in the shape of the nautilus. Some are more or less oblong, each new segment being nearly equal to the entire length of the shell.

Rotalia

One group will take the spherical form and produce a shell in the shape of the nautilus. Some are more…

Rotifers are free-swimming pseudo-coelomates. They occur in freshwater and are easily examined because they are transparent.

Rotifer

Rotifers are free-swimming pseudo-coelomates. They occur in freshwater and are easily examined because…

The rotifer or "wheel animalcule" owes its name to the fact that the anterior end of the body is almost always furnished with one or two circlets of cilia.

Rotifer

The rotifer or "wheel animalcule" owes its name to the fact that the anterior end of the body is almost…

The rotifer or "wheel animalcule" owes its name to the fact that the anterior end of the body is almost always furnished with one or two circlets of cilia.

Rotifer

The rotifer or "wheel animalcule" owes its name to the fact that the anterior end of the body is almost…

This diagram shows a sagittal section of a Rotifer. b, brain; bl., excretory bladder; c, cloaca, the common opening of digestive and reproductive organs; co, caelom; e, eyespot; ex, excretory canal; f, flame cells; f.g., foot gland; ft., foot; g, gut; m, mouth; m.f., longitudinal muscle fibres; mx, mastax; o, ovary; pf., pharynx; s.g., salivary gland; t, tentacle; tr, trochus, or cilia-bearing disc.

Rotifer

This diagram shows a sagittal section of a Rotifer. b, brain; bl., excretory bladder; c, cloaca, the…

Echlanis macrura is a species of rotifer, a microscopic planktonic animal.

Rotifer

Echlanis macrura is a species of rotifer, a microscopic planktonic animal.

A rotifer or wheel animalcule (Floscularia ornata) is a microscopic animal named for the cilia used in motion.

Rotifer

A rotifer or wheel animalcule (Floscularia ornata) is a microscopic animal named for the cilia used…

"Spore-formation in Vibrio-like (c) and Spirillum-like (a, b, d) Schizomycetes." &mdash; The Encyclopedia Britannica, 1910

Schizomycetes

"Spore-formation in Vibrio-like (c) and Spirillum-like (a, b, d) Schizomycetes." — The Encyclopedia…

"Types of spermatozoa. A, from the round worm (Ascaris) with a cap, somewhat amaeboid; B, from the Crayfish, with numerous projections; C, from Frog; D, from Sea-urchin. h, head; m, middle piece; n, nucleus; t, tailor flagelium." &mdash; Galloway

Spermatozoa

"Types of spermatozoa. A, from the round worm (Ascaris) with a cap, somewhat amaeboid; B, from the Crayfish,…

"Spirillum containing many spores (a), which are liberated at b by the breaking up of the parent cells." &mdash; The Encyclopedia Britannica, 1910

Spirillum

"Spirillum containing many spores (a), which are liberated at b by the breaking up of the parent cells."…

"Spirillum Rubrum, Esmarsch." &mdash; The Encyclopedia Britannica, 1910

Spirillum Rubrum

"Spirillum Rubrum, Esmarsch." — The Encyclopedia Britannica, 1910

"Spirillum Rubrum, Esmarsch." &mdash; The Encyclopedia Britannica, 1910

Spirillum Rubrum

"Spirillum Rubrum, Esmarsch." — The Encyclopedia Britannica, 1910

"Spirillum Undula, Ehrunb." &mdash; The Encyclopedia Britannica, 1910

Spirillum Undula

"Spirillum Undula, Ehrunb." — The Encyclopedia Britannica, 1910

"Spirillum Undula, Ehrunb." &mdash; The Encyclopedia Britannica, 1910

Spirillum Undula

"Spirillum Undula, Ehrunb." — The Encyclopedia Britannica, 1910

One group will take the spherical form and produce a shell in the shape of the nautilus. Some are more or less oblong, each new segment being nearly equal to the entire length of the shell.

Spiroloculina Depressa

One group will take the spherical form and produce a shell in the shape of the nautilus. Some are more…

"The pores of sponges are of two kinds, the larger ones called 'oscula'" and the smaller distinguished as 'pores.' In the living state of the sponge, water is being constantly absorbed by the pores, while currents of water will be seen issuing from the oscula."

Sponge Attached to its Rocky Bed

"The pores of sponges are of two kinds, the larger ones called 'oscula'" and the smaller distinguished…

"Long rod-like form containing a spore (these are the so-called "Kopfchenbacterien" of German authors)." &mdash; The Encyclopedia Britannica, 1910

Spore

"Long rod-like form containing a spore (these are the so-called "Kopfchenbacterien" of German authors)."…

"Germination of the spore of the hay bacillus&mdash;the axis of growth of the germinal rodlet is at right angles to the long axis of the spore." &mdash; The Encyclopedia Britannica, 1910

Spore

"Germination of the spore of the hay bacillus—the axis of growth of the germinal rodlet is at…

A spore.

Spore

A spore.

"The various phases of germination of spore of <em>Bacillus ramosus</em>, as actually observed in hanging drops under very high powers." &mdash; Encyclopediia Britannica, 1910

sporegerm

"The various phases of germination of spore of Bacillus ramosus, as actually observed in hanging…

"Telento spores, one germinating, bearing conidia."&mdash;Finley, 1917

Telento spore

"Telento spores, one germinating, bearing conidia."—Finley, 1917

"Various stages in the development of the endogenous spores in a Clostridium &mdash; the small letters indicate the order." &mdash; The Encyclopedia Britannica, 1910

Spores

"Various stages in the development of the endogenous spores in a Clostridium — the small letters…

"Endogenous spores of the hay bacillus." &mdash; The Encyclopedia Britannica, 1910

Spores

"Endogenous spores of the hay bacillus." — The Encyclopedia Britannica, 1910

"Cyst containing spores, 5. cyst, 7. spores, 8. ducts"&mdash;Finley, 1917

Sporozoa containing spores

"Cyst containing spores, 5. cyst, 7. spores, 8. ducts"—Finley, 1917

These are very destructive parasites that attack valuable crops. Rusty lines and dots appear on the leaves, which are masses of spores called summer spores.

Summer Spores (Uredospores) on wheat

These are very destructive parasites that attack valuable crops. Rusty lines and dots appear on the…

One group will take the spherical form and produce a shell in the shape of the nautilus. In this case, the new segments are arranged alternately on opposite sides of the central line.

Textularia Variabilis

One group will take the spherical form and produce a shell in the shape of the nautilus. In this case,…

"Section of Stratified Thallus of Ricasolia herbacea. a, cortical stratum; b, gonidial stratum; c, medullary stratum." &mdash;The Encyclopedia Britannica, 1910

Thallus

"Section of Stratified Thallus of Ricasolia herbacea. a, cortical stratum; b, gonidial stratum; c, medullary…

"Section of Unstratified Thallus of Collema conglomeratum, with Moniliform Gonimia scattered amongst the Hyphal Filaments." &mdash;The Encyclopedia Britannica, 1910

Thallus

"Section of Unstratified Thallus of Collema conglomeratum, with Moniliform Gonimia scattered amongst…

"1. Trypanosoma gambiense, showing nucleus, blepharoplast, and flagellum. 2 and 3. Individuals undergoing longitudinal fission. 4. Leucocyte engulfing a trypanosome." -Thomson, 1916

Trypanosoma Gambiense

"1. Trypanosoma gambiense, showing nucleus, blepharoplast, and flagellum. 2 and 3. Individuals undergoing…

"Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical biastoder. Ect., ectoderm; Ent., entoderm; Mes., mesoderm; c, primitive connective tissue." &mdash; Encyclopedia Britannica, 1893

Unilaminar

"Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical biastoder.…

"Vibrio form with spore." &mdash; The Encyclopedia Britannica, 1910

Vibrio

"Vibrio form with spore." — The Encyclopedia Britannica, 1910

"Volvox globator. A, entire colony, enclosing several daughter-colonies; B, the same during sexual maturity; C, four zooids in optical section; D1-D5, asexual formation of daughter-colony; E, zooid which has become converted into a mass of microgametes; F, microgamete; G, megagamete surrounded by microgametes; H, zygote; a, early stages in the formation of daughter-colonies; fl, flagellum; ov, ovy, megagametes; pg, pigment spot; spy, zooids containing microgametes." -Parker, 1900

Volvox Globator

"Volvox globator. A, entire colony, enclosing several daughter-colonies; B, the same during sexual maturity;…

"The common Volvox is found in great abundance during the summer, and even in the depth of winter in lakes and ponds of fresh water."

Volvox Globular

"The common Volvox is found in great abundance during the summer, and even in the depth of winter in…

"The common Volvox is found in great abundance during the summer, and even in the depth of winter in lakes and ponds of fresh water."

Volvox Globular

"The common Volvox is found in great abundance during the summer, and even in the depth of winter in…

"Vorticella. 1. Structure. N., Macronucleus; n., micronucleus; c.v., contractile vacuole; m., mouth; f.v., food vacuole; v., vestibule. 2. Encysted individual. 3. Division. 4. Separation of a free-swimming unit--the result of a division. 5. Formation of eight minute units (mg.). 6. Conjugation of microzooid (mg.) with one normal size." -Thomson, 1916

Vorticella

"Vorticella. 1. Structure. N., Macronucleus; n., micronucleus; c.v., contractile vacuole; m., mouth;…

"A, Vorticella, a stalked ciliate Infusorian; I, contracted; 2, extended. f, food "vacuoles"; g, gullet; m, contractile fibre (muscular); n, nucleus; o, mouth, surrounded by ciliated disc; p.v., pulsating vacuole; s, stalk. B, a colonial type similar to Vorticella." -Galloway, 1915

Vorticella

"A, Vorticella, a stalked ciliate Infusorian; I, contracted; 2, extended. f, food "vacuoles"; g, gullet;…

"Vorticella. A, B, living specimens in different positions; C, optical section; D1, D2, diagrams illustrating coiling of stalk; E1, E2, two stages in binary fission; E3, free zooid; F1, F2, division into mega- and microzooids; G1, G2, conjugation; H1, multiple fission of encysted form; H2, H3, development of spores; ax. f, axial fibre; cort, cortex; cu, cuticle; c. vac, contractile vacuole; d, disc; gull, gullet; m, microzooid; mth, mouth; nu, meganucleus; per, peristome." -Parker, 1900

Vorticella

"Vorticella. A, B, living specimens in different positions; C, optical section; D1, D2, diagrams illustrating…

"A water-Bear, or Bear-animalcule (Macrobiotus schultzei), one of the Arctisca or Tardigradam, much magnified. 1,2,3,4, the limbs; a, mouth with six oral papill&aelig;; b, gullet, calcified stylets; c, salivary glands; d, muscluar pharynx; e, ovary; f, vesicul seminalis; g, testes."-Whitney, 1902

Water Bear

"A water-Bear, or Bear-animalcule (Macrobiotus schultzei), one of the Arctisca or Tardigradam, much…

These are very destructive parasites that attack valuable crops. Black lines and dots appear on the wheat forming masses of spores called winter spores.

Winter Spores (teleutospores) on wheat

These are very destructive parasites that attack valuable crops. Black lines and dots appear on the…

"Mixed zoogloea found as a pellicle on the surface of vegetable infusions; it consists of various forms, and contains cocci (a) and rodlets, in series (b and c)." &mdash; The Encyclopedia Britannica, 1910

Zoogloea

"Mixed zoogloea found as a pellicle on the surface of vegetable infusions; it consists of various forms,…

"Egg-shaped mass of zoogloea of Beggiatoa roseo-persicina (Bacterium rubescens of Lankster); the gelatinous swollen walls of the large crowded cocci are fused into a common gelatinous envelope." &mdash; The Encyclopedia Britannica, 1910

Zoogloea

"Egg-shaped mass of zoogloea of Beggiatoa roseo-persicina (Bacterium rubescens of Lankster); the gelatinous…

"Reticulate zoogloea of the same." &mdash; The Encyclopedia Britannica, 1910

Zoogloea

"Reticulate zoogloea of the same." — The Encyclopedia Britannica, 1910

"Branched fruticose zoogloea of Cladothrix." &mdash; The Encyclopedia Britannica, 1910

Zoogloea

"Branched fruticose zoogloea of Cladothrix." — The Encyclopedia Britannica, 1910

"Zoogloea of Bacterium merismopedioides, Zopf, containing cocci arranged in tablets." &mdash; The Encyclopedia Britannica, 1910

Zoogloea

"Zoogloea of Bacterium merismopedioides, Zopf, containing cocci arranged in tablets." — The Encyclopedia…

"A. Mixed Zoogloea found as a pellicle on the surface of vegetable infusions &c; it consists of various forms, and contains cocci (a) and rodlets, in series (b and C), &c. B. Egg-shaped mass of zoogloea of <em>Beggiatoa roseo-persicina</em> (<em>Bacterium rubescens</em> of Lankester); the gelatinous swollen walls of the large crowded cocci are fused into a common gelatinous envelope. C. Reticulate zoogloea of the same. D, E, H. Colonies of <em>Myconostoc</em> enveloped in diffluent matrix. F. Branched fruticose zoogfoea of <em>Cladothrix</em>. G. Zoogloea of <em>Bacterium merismopediodes</em>, Zopf, containing cocci arranged in tablets." &mdash; Encyclopediia Britannica, 1910

Types of Zoogloea

"A. Mixed Zoogloea found as a pellicle on the surface of vegetable infusions &c; it consists of various…

"Zygospore from two conidia conjoined."&mdash;Finley, 1917

Zygospore

"Zygospore from two conidia conjoined."—Finley, 1917