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.

"Actinomma, a radiolarian with a shell and no mouth. A, whole animal with a portion of two spheres of shell removed. B, section, showing relation of protoplasm to the skeleton. c., central capsule; n, nucleus; p, protoplasm; o, openings through which the pseudopodia extend." -Galloway, 1915

Actinomma

"Actinomma, a radiolarian with a shell and no mouth. A, whole animal with a portion of two spheres of…

"Actinomma Asteracanthion, a Radiolarian with a limited number of specialized radii (axes), symmetrically arranged about the center. A, whole animal with portion of two spheres of shell removed. B, section, showing relation of the protoplasm to the skeleton. n, nucleus; p, protoplasm; sk., skeleton." — Galloway

Actinomma Asteracanthion

"Actinomma Asteracanthion, a Radiolarian with a limited number of specialized radii (axes), symmetrically…

"The Foraminifera are enclosed in minute calcareous shells, early invisible to the naked eye; they are found among the sands of the sea. The, in common with corals, are great agents in helping to form islands, which rise out of the bosom of the deep in the warm regions of the globe."

Alveolina Ovoidea (d'Orbigny)

"The Foraminifera are enclosed in minute calcareous shells, early invisible to the naked eye; they are…

"Amaeba proteus; B, Amaeba radiosa. n, nucleus. c, contractile vacuole. a, food engulfed. ec, one of the nine pseudopods." —Davison, 1906

Amaeba Proteus

"Amaeba proteus; B, Amaeba radiosa. n, nucleus. c, contractile vacuole. a, food engulfed. ec, one of…

"A term etymologically applicable to any very small animal, and limited in actual use to those which are microscopical. Animalcules exist in prodigious numbers, and of many different kinds, their size being such that multitudes of them find ample space for all the movements of an active life within a single drop of water; and they abound almost wherever there is moisture, at least wherever organic matter is present." — Chambers' Encyclopedia, 1875

Animalcule

"A term etymologically applicable to any very small animal, and limited in actual use to those which…

"Actinophrys sol (Sun animalcule). n., nucleus; f.v., food vacuole; v., contractile vacuole; ps., pseudopodium." -Thomson, 1916

Sun Animalcule

"Actinophrys sol (Sun animalcule). n., nucleus; f.v., food vacuole; v., contractile vacuole; ps., pseudopodium."…

"They are trumpet-animalcules of the family Stentoridae, with the peristome divided into two lappet-like parts. Folliculina ampulla is an example." -Whitney, 1911

Trumpet Animalcule

"They are trumpet-animalcules of the family Stentoridae, with the peristome divided into two lappet-like…

"Fig. 1, Monads; 2, Forms assumed by the Ameoba; 3, Flask Animalcules, Enchelis; 4, Actinophrys sol; 5, Euglena viridis ; 6, Gonium pectorale; 7, Trachelias anas ; 8, Paramecium aurelia ; 9, Navicula; 10, Vibrie Spirillum; 11, Vorticella Stentor" — Goodrich, 1859

Forms of the animalcules, magnified

"Fig. 1, Monads; 2, Forms assumed by the Ameoba; 3, Flask Animalcules, Enchelis; 4, Actinophrys sol;…

A diagram of an annulosa showing its external skeleton made up of segments or rings arranged along a longitudinal line, and consisting mostly of hardened skin. Labels: 1, vascular system,; 2, digestive organs; 3, ganglia.

Diagram of an Annulosa

A diagram of an annulosa showing its external skeleton made up of segments or rings arranged along a…

This illustration shows further development of the ascocarp: A, sectional view, showing the branches, s, derived from the germinating gametospore, that are forming numerous lateral branchlets. B, one of the branchlets enlarged, showing how it divides into cells which round off, forming the asci, as. C, ascospore. D, germinating ascspore.

Ascocarp

This illustration shows further development of the ascocarp: A, sectional view, showing the branches,…

"The common <em>Flustrae</em>, or <em>Sea-mats</em>, are flat and foliaceous in their form, presenting a considerable resemblence to in appearence to pale-brown sea-weeds, with which they are in fact generally confounded by sea-side visitors." &mdash; Goodrich, 1859

Flustra, avicularia

"The common Flustrae, or Sea-mats, are flat and foliaceous in their form, presenting…

"Bacilli mingles with blood-corpuscles from the blood of a guinea-pig; some of the bacilli dividing." &mdash; The Encyclopedia Britannica, 1910

Bacillus Anthracis

"Bacilli mingles with blood-corpuscles from the blood of a guinea-pig; some of the bacilli dividing."…

"The rodlets after three hours' culture in a drop of aqueous humour. They grow out into long leptothrix-like filaments, which become septate later, and spores are developed in the segments." &mdash; The Encyclopedia Britannica, 1910

Bacillus Anthracis

"The rodlets after three hours' culture in a drop of aqueous humour. They grow out into long leptothrix-like…

"A chain of motile rodlets still growing and dividing (bacilli)." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"A chain of motile rodlets still growing and dividing (bacilli)." — The Encyclopedia Britannica,…

"A pair of bacilli actively growing and dividing." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"A pair of bacilli actively growing and dividing." — The Encyclopedia Britannica, 1910

"A rodlet in this condition (but divided into four segments) after treatment with alcoholic iodine solution." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"A rodlet in this condition (but divided into four segments) after treatment with alcoholic iodine solution."…

"Successive stages in the development of the spores." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"Successive stages in the development of the spores." — The Encyclopedia Britannica, 1910

"A rodlet segmented in four, each segment containing one ripe spore." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"A rodlet segmented in four, each segment containing one ripe spore." — The Encyclopedia Britannica,…

"Early stages in the germination of the spores (after being dried several days)." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"Early stages in the germination of the spores (after being dried several days)." — The Encyclopedia…

"Successive stages in the germination of the spore." &mdash; The Encyclopedia Britannica, 1910

Bacillus Megaterium

"Successive stages in the germination of the spore." — The Encyclopedia Britannica, 1910

"The various phases of germination of spores of Bacillus ramosus, as actually observed in hanging drops under very high powers. The spore sown at 11 A.M., as shown at a, had swollen (b) perceptibly by noon, and had germinated by 3:30 P.M., as shown at c: in d at 6 P.M., and e at 8:30 P.M.; the resulting filament is segmenting into bacilli as it elongates, and at midnight (f) consisted of twelve such segments." &mdash; The Encyclopedia Britannica, 1910

Bacillus Ramosus

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

"The various phases of germination of spores of Bacillus ramosus, as actually observed in hanging drops under very high powers. Similar series of phases in the order of the small letters in each case, and with the times of observation attached. At f and g occurs the breaking up of the filament into rodlets." &mdash; The Encyclopedia Britannica, 1910

Bacillus Ramosus

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

"The various phases of germination of spores of Bacillus ramosus, as actually observed in hanging drops under very high powers. Similar series of phases in the order of the small letters in each case, and with the times of observation attached. At f and g occurs the breaking up of the filament into rodlets." &mdash; The Encyclopedia Britannica, 1910

Bacillus Ramosus

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

"The various phases of germination of spores of Bacillus ramosus, as actually observed in hanging drops under very high powers. Germinating spores in various stages, more highly magnified, and showing the different ways of escape of the filament from the spore-membrane." &mdash; The Encyclopedia Britannica, 1910

Bacillus Ramosus

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

"Bacillus subtilis, Cohn, and Spirillum undula, Ehrenb." &mdash; The Encyclopedia Britannica, 1910

Bacillus Subtilis

"Bacillus subtilis, Cohn, and Spirillum undula, Ehrenb." — The Encyclopedia Britannica, 1910

"Bacillus Typhi, Gaffky." &mdash; The Encyclopedia Britannica, 1910

Bacillus Typhi

"Bacillus Typhi, Gaffky." — The Encyclopedia Britannica, 1910

"Bacillus Vulgaris, Migula." &mdash; The Encyclopedia Britannica, 1910

Bacillus Vulgaris

"Bacillus Vulgaris, Migula." — The Encyclopedia Britannica, 1910

Bacteria that cause blight.

Bacteria

Bacteria that cause blight.

Harmless bacteria so numerous in drinking water that a person often takes a half-million into his stomach daily.

Bacteria

Harmless bacteria so numerous in drinking water that a person often takes a half-million into his stomach…

Useful bacteria which change dead matter into food for the grass, wheat, and corn.

Bacteria

Useful bacteria which change dead matter into food for the grass, wheat, and corn.

"Brachionus rubens. A, from the dorsal aspect; B, from the right side. a, anus; br, brain; d. f. dorsal feeler; c. gl, cement gland; cl, cloaca; c. l, ciliary lobes; c. v, contractile vesicle; e, eye-spot; int, intestine; lr, lorica; l. f, lateral feeler; m, muscular bands; nph, nephridial tubes; ov, ovary; ph, pharynx; st, stomach; t, tail; tr, d, trochal disc; vt, vitellarium." -Parker, 1900

Brachionus Rubens

"Brachionus rubens. A, from the dorsal aspect; B, from the right side. a, anus; br, brain; d. f. dorsal…

A modern Bryozoan, a group of cells or zooecia seen from above, and a single cell seen from the side.

Bryozoan

A modern Bryozoan, a group of cells or zooecia seen from above, and a single cell seen from the side.

A modern Bryozoan, a single zooid expanded.

Bryozoan

A modern Bryozoan, a single zooid expanded.

A modern Bryozoan, a cluster of branches.

Bryozoan

A modern Bryozoan, a cluster of branches.

A modern Bryozoan, a single branch bearing ovicells and zooid cells.

Bryozoan

A modern Bryozoan, a single branch bearing ovicells and zooid cells.

"The Foraminifera are enclosed in minute calcareous shells, early invisible to the naked eye; they are found among the sands of the sea. The, in common with corals, are great agents in helping to form islands, which rise out of the bosom of the deep in the warm regions of the globe."

Calcarina Calcitrpoides (Lamarck)

"The Foraminifera are enclosed in minute calcareous shells, early invisible to the naked eye; they are…

One group will take the spherical form and produce a shell in the shape of the nautilus. In this case, the shell is spiral, with the chamber equilateral, with a larger and smaller side.

Cassidulina Laevigata

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

"Various stages of cell multiplication by budding of Saccharomyces cerevisiae." -Stevens, 1916

S. Cerevisiae Cell Multiplication

"Various stages of cell multiplication by budding of Saccharomyces cerevisiae." -Stevens, 1916

"A colony of Cercomonas termo, a typical flagellate infusorian." -Whitney, 1911

Cercomonad Flagellate

"A colony of Cercomonas termo, a typical flagellate infusorian." -Whitney, 1911

"Clostridium&mdash;one cell contains two spores." &mdash; The Encyclopedia Britannica, 1910

Clostridium

"Clostridium—one cell contains two spores." — The Encyclopedia Britannica, 1910

"Germination of spore of Clostridium butyricum&mdash;the axis of growth coincides with the long axis of the spore." &mdash; The Encyclopedia Britannica, 1910

Clostridium

"Germination of spore of Clostridium butyricum—the axis of growth coincides with the long axis…

These are very destructive parasites that attack valuable crops. Cluster-cups are orange-colored spores in little cup-like clusters.

Cluster-Cups on Barberry (Lower Side)

These are very destructive parasites that attack valuable crops. Cluster-cups are orange-colored spores…

"A chair of cocci of Leuconostoc mesenterioides, with two "resting spores," i.e. anthrospores." &mdash; The Encyclopedia Britannica, 1910

Cocci

"A chair of cocci of Leuconostoc mesenterioides, with two "resting spores," i.e. anthrospores." —…

"Life history of Coccidium. 1. Sporozoite; 2. Sporozoite entering a cell and becoming a trophozoite; 3-4. Schizont, forming merozoites; 5. Merozoites entering another cell; 6a. Merozoite forming macrogamete; 6b. Merozoite forming microgametes; 7. Free microgamete; 8-9. Fertilisation of macrogamete by microgamete; 10. Zygote within oocyst; 11. Formation of spores within oocyst; 12. Spores forming sporozoites." -Thomson, 1916

Coccidium

"Life history of Coccidium. 1. Sporozoite; 2. Sporozoite entering a cell and becoming a trophozoite;…

"The shell advances beyond this simple type by a process of linear budding, the first cell being spherical, with an opening through which a second segment is formed, generally a little larger than the first. This new growth is followed by others developed in the same way, until the organism attains its maturity."

Dentalina Subarcuata

"The shell advances beyond this simple type by a process of linear budding, the first cell being spherical,…

"Various forms of Dinoflagellata. 1. Glenodinium 2. Ceratium 3. Prorocentrum 4. Polykrikos. 2 shows the shell only; 4a is an undischarged, and b a discharged stinging-capsule; chr, chromatophores; fl. 1, longitudinal flagellum; fl. 2, transverse flagellum; l. gr, longitudinal groove; ntc, nematocyst; nu, meganucleus; nu, micronucleus; pg, pigment spot; t. gr, transverse groove." -Parker, 1900

Dinoflagellates

"Various forms of Dinoflagellata. 1. Glenodinium 2. Ceratium 3. Prorocentrum 4. Polykrikos. 2 shows…

"A pelagic family of radioflagellate infusorians, typified by the genus Euchitonia. The animalcules are free-floating." -Whitney, 1911

Euchitonia

"A pelagic family of radioflagellate infusorians, typified by the genus Euchitonia. The animalcules…

"Eudorina. A colony of 16 flagellate cells imbedded in a gelatinous matrix." &mdash; Galloway

Eudorina

"Eudorina. A colony of 16 flagellate cells imbedded in a gelatinous matrix." — Galloway

Euglena viridis is a species of unicellular protists in the Euglenaceae family of flagellate organisms.

Euglena

Euglena viridis is a species of unicellular protists in the Euglenaceae family of flagellate organisms.

"A, Euglena viridis, a flagellate Infusorian. I, typical swimming condition; 2, somewhat contracted; 3, spherical resting condition; 4, encysted stage in which fission has taken place. c, cyst; f, flagellum; n, nucleus; o, mouth; p.v., pulsating vacuole; sp, pigment spot. B, Podophrya, a stalked Infusorian bearing tentacles (t). p, Infusorian captured for food; s, stalk." -Galloway, 1915

Euglena Viridis

"A, Euglena viridis, a flagellate Infusorian. I, typical swimming condition; 2, somewhat contracted;…

"Euglena viridis. A-D, four views illustrating euglenoid movements; E and H, enlarged views; F, anterior end further enlarged; G, resting form after binary fission; c. vac, contractile vacuole in H, reservoir in E and F; cy, cyst; fl, flagellum; m, mouth; nu, nucleus; oes, gullet; p, paramylum bodies; pg, pigment spot; r (in H), reservoir." -Parker, 1900

Euglena Viridis

"Euglena viridis. A-D, four views illustrating euglenoid movements; E and H, enlarged views; F, anterior…

"This is the most common species of the <em>Euglenia</em>, and is among the most widely diffused of all the Infusioria. It is this animalcule which is often met with covering stagnant pools with a floating surface of green."

Euglena Viridis

"This is the most common species of the Euglenia, and is among the most widely diffused of…

"The Foraminifera are enclosed in minute calcareous shells, early invisible to the naked eye; they are found among the sands of the sea. The, in common with corals, are great agents in helping to form islands, which rise out of the bosom of the deep in the warm regions of the globe."

Fabularia Discolithus (Defrance)

"The Foraminifera are enclosed in minute calcareous shells, early invisible to the naked eye; they are…

Flagellata is an order of Protozoa characterized by the presence of flagellae (whip-like structures used for locomotion). In many flagellate forms, chlorophyll is present. These forms have been regarded by botanists as minute algae. This illustration shows 3 flagellates: 1) Ceratium Tripos, 2) Noctiluca, and 3) Euglena.

Flagellata

Flagellata is an order of Protozoa characterized by the presence of flagellae (whip-like structures…

"A Foraminifer (Polystomella) showing shell and pseudopodia." -Thomson, 1916

Foraminifer

"A Foraminifer (Polystomella) showing shell and pseudopodia." -Thomson, 1916

"A pelagic Foraminifer." -Thomson, 1916

Foraminifer

"A pelagic Foraminifer." -Thomson, 1916

"Formation of shell in a simple Foraminifer. In A the shell has one chamber; B, C, and D show the formation of a second. Note outflowing pseudopodia and the enclosure of the shell by a thin layer of protoplasm; note also the nucleus in the central protoplasm." -Thomson, 1916

Foraminifer Shell Formation

"Formation of shell in a simple Foraminifer. In A the shell has one chamber; B, C, and D show the formation…

"Diagrams of Foraminifera. A, monothalamian; B, C, polythalamian; D, horizontal, and E, F, vertical sections of the helicoid forms." -Whitney, 1911

Diagrams of Foraminifera

"Diagrams of Foraminifera. A, monothalamian; B, C, polythalamian; D, horizontal, and E, F, vertical…

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the perforate test free and calcareous, its several chambers inflated or globose and arranged in a turbinate spiral, the aperture simple or multiple and conspicuous, opening into an umbilical depression, and no supplementary skeleton or canal system." -Whitney, 1911

Globigerina

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the…

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the perforate test free and calcareous, its several chambers inflated or globose and arranged in a turbinate spiral, the aperture simple or multiple and conspicuous, opening into an umbilical depression, and no supplementary skeleton or canal system." -Whitney, 1911

Globigerina

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the…