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Nervous system of a flatworm. Labels: G, cerebral ganglia and eyes; St, the two lateral nerve trunks; D, intestine with mouth.

Nervous System of the Flatworm

Nervous system of a flatworm. Labels: G, cerebral ganglia and eyes; St, the two lateral nerve trunks;…

Nervous system of the larva of a ladybug. Labels: Gfr, frontal ganglion; G, cerebral ganglia; Sg, subcesophageal ganglion; G'-G", ganglia of the ventral chain.

Nervous System of a Ladybug Larva

Nervous system of the larva of a ladybug. Labels: Gfr, frontal ganglion; G, cerebral ganglia; Sg, subcesophageal…

Nervous system of an adult ladybug. Ag, optic ganglion.

Nervous System of a Ladybug

Nervous system of an adult ladybug. Ag, optic ganglion.

A, Diagrammatic transverse section through the body of a vertebrate. B, A similar section through a highly organized invertebrate animal. Labels: a, neural canal; b, cerebrospinal nerve center; c, notochord; d, sympathetic nerve center; e, alimentary canal; f, visceral canal wall; g, haemal system.

Vertebrate and Invertebrate

A, Diagrammatic transverse section through the body of a vertebrate. B, A similar section through a…

Samuel Finley Breese Morse (April 27, 1791 – April 2, 1872) was an American painter of portraits and historic scenes, the creator of a single wire telegraph system, and co-inventor, with Alfred Vail, of the Morse Code.

Samuel Finley Breese Morse

Samuel Finley Breese Morse (April 27, 1791 – April 2, 1872) was an American painter of portraits…

Cirsium arvense is a species of Cirsium, native throughout Europe and northern Asia, and widely introduced elsewhere. The standard English name in its native area is Creeping Thistle. It is a tall herbaceous perennial plant, forming extensive clonal colonies from an underground root system that sends up numerous erect stems each spring, reaching 1–1.2 m tall (occasionally more); the stems often lie partly flat by summer but can stay erect if supported by other vegetation. The leaves are very spiny, lobed, up to 15–20 cm long and 2–3 cm broad (smaller on the upper part of the flower stem). The inflorescence is 10–22 mm diameter, pink-purple, with all the florets of similar form (no division into disc and ray florets). The flowers are usually dioecious, but not invariably so, with some plants bearing hermaphrodite flowers. The seeds are 4–5 mm long, with a feathery pappus which assists in wind dispersal.

Canada Thistle

Cirsium arvense is a species of Cirsium, native throughout Europe and northern Asia, and widely introduced…

The brook trout, Salvelinus fontinalis, (sometimes called the eastern brook trout, Adirondack coaster lake trout) is a species of fish in the salmon family of order Salmoniformes. The brook trout is native to small streams, creeks, lakes, and spring ponds. Some brook trout are anadromous. It is native to a wide area of eastern North America but increasingly confined to higher elevations southward in the Appalachian Mountains to northern Georgia, Canada from the Hudson Bay basin east, the Great Lakes–Saint Lawrence system, and the upper Mississippi River drainage as far west as eastern Iowa.

Brook Trout

The brook trout, Salvelinus fontinalis, (sometimes called the eastern brook trout, Adirondack coaster…

An illustration of the Order of the Garter Star. The Most Noble Order of the Garter is an order of chivalry, or knighthood, originating in medieval England, and presently bestowed on recipients in any of the Commonwealth realms; it is the pinnacle of the honors system in the United Kingdom. Membership in the order is limited to the sovereign, the Prince of Wales, and no more than twenty-four members, or Companions; the order also comprises Supernumerary knights and ladies (e.g., members of the British Royal Family and foreign monarchs).

Order of the Garter Star

An illustration of the Order of the Garter Star. The Most Noble Order of the Garter is an order of chivalry,…

An illustration of a sea fern fossil from the carboniferous period. The Carboniferous is a geologic period and system that extends from the end of the Devonian period, about 359.2 ± 2.5 Ma (million years ago), to the beginning of the Permian period, about 299.0 ± 0.8 Ma.

Sea Fern Fossil

An illustration of a sea fern fossil from the carboniferous period. The Carboniferous is a geologic…

A, crepidoma or stylobate; B, column; C, architrave; D, tænia; E, frieze; F, horizontal cornice; G, raking cornice; H, tympanum of pediment; K, metope. In this and other cuts of this order, only the upper and lower parts of the shaft are shown, the intervening and greater part of the shaft being omitted, to save space.

Greek Doric Order

A, crepidoma or stylobate; B, column; C, architrave; D, tænia; E, frieze; F, horizontal cornice;…

The Ionic order column originated in the mid-6th century BC in Ionia. The Ionic order column was being practiced in mainland Greece in the 5th century BC. The first of the great Ionic temples was the Temple of Hera on Samos, built about 570 BC–560 BC by the architect Rhoikos. It stood for only a decade before it was leveled by an earthquake. It was in the great sanctuary of the goddess: it could scarcely have been in a more prominent location for its brief lifetime. A longer-lasting 6th century Ionic temple was the Temple of Artemis at Ephesus, one of the Seven Wonders of the Ancient World.

Greek Ionic Order

The Ionic order column originated in the mid-6th century BC in Ionia. The Ionic order column was being…

The Ionic order column originated in the mid-6th century BC in Ionia. The Ionic order column was being practiced in mainland Greece in the 5th century BC. The first of the great Ionic temples was the Temple of Hera on Samos, built about 570 BC–560 BC by the architect Rhoikos. It stood for only a decade before it was leveled by an earthquake. It was in the great sanctuary of the goddess: it could scarcely have been in a more prominent location for its brief lifetime. A longer-lasting 6th century Ionic temple was the Temple of Artemis at Ephesus, one of the Seven Wonders of the Ancient World.

Greek Ionic Order (Side View)

The Ionic order column originated in the mid-6th century BC in Ionia. The Ionic order column was being…

The Corinthian order is one of the Classical orders of Greek and Roman architecture, characterized by a slender fluted column and an ornate capital decorated with acanthus leaves and scrolls. Although of Greek origin, the Corinthian order was seldom used in Greek architecture.

Greek Corinthian Order

The Corinthian order is one of the Classical orders of Greek and Roman architecture, characterized by…

The Ionic order column originated in the mid-6th century BC in Ionia. The Ionic order column was being practiced in mainland Greece in the 5th century BC. The first of the great Ionic temples was the Temple of Hera on Samos, built about 570 BC-560 BC by the architect Rhoikos. It stood for only a decade before it was leveled by an earthquake. It was in the great sanctuary of the goddess: it could scarcely have been in a more prominent location for its brief lifetime. A longer-lasting 6th century Ionic temple was the Temple of Artemis at Ephesus, one of the Seven Wonders of the Ancient World.

Roman Ionic Order

The Ionic order column originated in the mid-6th century BC in Ionia. The Ionic order column was being…

An illustration of a small jellyfish. Jellyfish are free-swimming members of the phylum Cnidaria. ellyfish don't have specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems. They digest using the gastrodermal lining of the gastrovascular cavity, where nutrients are absorbed. They do not need a respiratory system since their skin is thin enough that the body is oxygenated by diffusion. They have limited control over movement and mostly free-float, but can use the hydrostatic skeleton of the water pouch to accomplish vertical movement through pulsations of the disc-like body.

Jellyfish

An illustration of a small jellyfish. Jellyfish are free-swimming members of the phylum Cnidaria. ellyfish…

An illustration depicting an astigmatism. An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances.

Diagram Illustrating Astigmatism

An illustration depicting an astigmatism. An optical system with astigmatism is one where rays that…

Troy weight is a system of units of mass customarily used for precious metals, black powder, and gemstones.

Troy Weight

Troy weight is a system of units of mass customarily used for precious metals, black powder, and gemstones.

Hundred weight or hundredweight is a unit of measurement for mass in U.S. customary units and was historically used in the Imperial system in the United Kingdom and the British Commonwealth.

Hundredweight

Hundred weight or hundredweight is a unit of measurement for mass in U.S. customary units and was historically…

"Zircon, a mineral composed of of zirconium silicate, sometimes used as a gem-stone... THe mineral crystallizes in the tetragonal system, generally in combinations of square prisms and square pyramids" (Britannica, 1910).

Zircon

"Zircon, a mineral composed of of zirconium silicate, sometimes used as a gem-stone... THe mineral crystallizes…

"Zircon, a mineral composed of of zirconium silicate, sometimes used as a gem-stone... THe mineral crystallizes in the tetragonal system, generally in combinations of square prisms and square pyramids." -Britannica, 1910

Zircon

"Zircon, a mineral composed of of zirconium silicate, sometimes used as a gem-stone... THe mineral crystallizes…

Constructive system of a Gothic church illustrating the principles of isolated supports and buttressing.

Constructive System of a Gothic Church

Constructive system of a Gothic church illustrating the principles of isolated supports and buttressing.

An illustration of a mechanical kettledrum showing the system of cords inside. Timpani (also known colloquially as kettledrums or kettle drums) are musical instruments in the percussion family. A type of drum, they consist of a skin called a head stretched over a large bowl commonly made of copper. They are played by striking the head with a specialized drum stick called a timpani stick or timpani mallet. Unlike most drums, they produce a definite pitch when struck, and can be tuned, often with the use of a pedal. Timpani evolved from military drums to become a staple of the classical orchestra by the last third of the 18th century. Today, they are used in many types of musical ensembles including concert, marching, and even some rock bands.

Mechanical Kettledrum

An illustration of a mechanical kettledrum showing the system of cords inside. Timpani (also known colloquially…

The digestive apparatus of the horse. Labels: a, mouth; 2, pharynx; 3, esophagus; 4, diaphragm; 5, spleen; 6, stomach (left sac); 7, duodenum; 8, liver (upper extremity); 9, great colon; 10, caecum; 11, small intestine; 12, floating colon; 13, rectum; 14, anus; 15, left kidney and ureter; 16, bladder; 17, urethra; a, hard palate; b, tongue; c, soft palate; d, trachea; e, pulmonary artery (divided); f, heart; g, posterior aorta.

Digestive Apparatus of the Horse

The digestive apparatus of the horse. Labels: a, mouth; 2, pharynx; 3, esophagus; 4, diaphragm; 5, spleen;…

The relation of anterior abdominal digestive organs- left antero-lateral view. Labels: 1, liver; 2, stomach; 3, spleen; 4, colon; a, gastro-hepatic omentum; b, gastro-splenic omentum; c, great omentum; c', its free portion.

Digestive Organs of a Horse

The relation of anterior abdominal digestive organs- left antero-lateral view. Labels: 1, liver; 2,…

An illustration of an Albert model clarinet. The Albert system refers to a system of clarinet keywork and fingering developed by Eugene Albert. In the United Kingdom it is known as the simple system. The Albert system is still used, mainly by clarinetists who perform Eastern European and Turkish folk music, Klezmer, and Dixieland styles. Often these musicians prefer the Albert system due to the ease of slurring notes provided by unkeyed tone holes

Clarinet (Albert Model)

An illustration of an Albert model clarinet. The Albert system refers to a system of clarinet keywork…

An illustration of an Boehm model clarinet. The Böhm system for the clarinet is a system of clarinet keywork, developed between 1839 and 1843 by Hyacinthe Klosé and Auguste Buffet jeune. The name is somewhat deceptive; the system was inspired by Theobald Boehm's system for the flute, but differs from it (necessarily, since the clarinet overblows at the twelfth rather than the flute's octave), and Boehm himself was not involved in its development.

Clarinet (Boehm Model)

An illustration of an Boehm model clarinet. The Böhm system for the clarinet is a system of clarinet…

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium; r, rectum; and Br, Ctenidia.

Chiton Excretory and Reproductive Organs

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium;…

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium; r, rectum; Cl, Cloacal or pallial chamber of Neomaniae and Chaetoerma; and Br, Ctenidia.

Chiton Excretory and Reproductive Organs

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium;…

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium; r, rectum; and Cl, Cloacal or pallial chamber of Neomaniae and Chaetoerma.

Chiton Excretory and Reproductive Organs

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium;…

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium; r, rectum; and Cl, Cloacal or pallial chamber of Neomaniae and Chaetoerma; Br, Ctenidia; g, External aperture of the gential duct of Chiton; and u, External aperture of nephridium.

Chiton Excretory and Reproductive Organs

An illustration of a chiton's excretory and reproductive organs. O, Ovary; P, Pericardium; N, Nephridium;…

General view of the respiratory organs. Labels: a, septum nasi; b, posterior naris; c, larynx; d, trachea; e, thyroid gland; f, anterior mediastinum; g, posterior mediastinum; h, left lung; h', its apex; h", its base; h"', its superior,and h"", its inferior borders.

Respiratory Organs of a Horse

General view of the respiratory organs. Labels: a, septum nasi; b, posterior naris; c, larynx; d, trachea;…

The nervous system of the horse. Labels: 1, brain; 2, optic nerve; 3, superior maxillary nerve (5th); 4, inferior maxillary nerve (5th); 5, pneumogastric nerve; 6, medulla oblongata; 6', spinal cord; 7, right brachial plexus; 8, musculo-cutaneous nerve; 9, median nerve; 10, radial nerve; 11, cubital nerve; 12, pneumogastric nerve; 13, solar plexus; 14, semilunar ganglion; 15m lumbo-sacral plexus; 16, anterior crural nerve; 17, great sciatic nerve; 18, external popiteal nerve; 19, external saphenic nerve; 20, tibial nerve; 21, metatarsal nerve; 22, radial portion of median nerve; 23, metacarpal nerves; 24, digital branches; s, sympathetic chain; c, inferior cervical plexus; g, gutteral ganglion; Sp, great splanchnic nerve; pm; posterior mesenteric plexus; p, pelvic plexus.

Nervous System of the Horse

The nervous system of the horse. Labels: 1, brain; 2, optic nerve; 3, superior maxillary nerve (5th);…

The cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact shape, and mellower tone quality. The most common cornet is a transposing instrument in B♭. It is not related to the medieval cornett or cornetto. The cornet was originally derived from the post horn. Sometimes it is called a cornopean, which refers to the earliest cornets with the Stölzel valve system.

Cornet

The cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact…

The cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact shape, and mellower tone quality. The most common cornet is a transposing instrument in B♭. It is not related to the medieval cornett or cornetto. The cornet was originally derived from the post horn. Sometimes it is called a cornopean, which refers to the earliest cornets with the Stölzel valve system.

Cornet

The cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact…

"inverted Vertical Pendulum Seismograph. Marvin System. A stiff vertical tube, pivoted at its bottom end, carries a very heavy mass near its upper end, and is rendered stable or astatic by the elastic reaction of a central steel rod which has its bottom end firmly fixed inside the heavy mass and its top end attached to the framework on the pier. The horizontal motion of the ground and pier relative to the steady mass is magnified 120 times and inscribed on smoked-paper record-sheets by two sets of multiplying levers. One records the north-south, the other the east-west component of motion." -Whitney, 1911

Pendulum Seismograph

"inverted Vertical Pendulum Seismograph. Marvin System. A stiff vertical tube, pivoted at its bottom…

An illustration of the young stages of Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Young Stage of Noctiluca Scintillans

An illustration of the young stages of Noctiluca scintillans. Noctiluca scintillans, also published…

An illustration of the young stages of Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Young Stage of Noctiluca Scintillans

An illustration of the young stages of Noctiluca scintillans. Noctiluca scintillans, also published…

An illustration of the first stage of fission in the Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Stage One in the Fission of Noctiluca Scintillans

An illustration of the first stage of fission in the Noctiluca scintillans. Noctiluca scintillans, also…

An illustration of the second stage of fission in the Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Stage Two in the Fission of Noctiluca Scintillans

An illustration of the second stage of fission in the Noctiluca scintillans. Noctiluca scintillans,…

An illustration of the aboral side view of the Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Aboral Side View of the Noctiluca Scintillans

An illustration of the aboral side view of the Noctiluca scintillans. Noctiluca scintillans, also published…

An illustration of the Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Noctiluca Scintillans

An illustration of the Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris,…

An illustration of the lateral view of the Noctiluca scintillans. Noctiluca scintillans, also published as Noctiluca miliaris, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. scintillans is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or "microsources", located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctiluca lack these microsources.

Lateral View of Noctiluca Scintillans

An illustration of the lateral view of the Noctiluca scintillans. Noctiluca scintillans, also published…

"Human Thoracic Duct and Azygous Veins. a, receptacle of the chyle; b, trunk of the thoracic duct, opening at c into root of left innominate vein at junction of f, left jugular, and g, left subclavian vein; e, right innominate vein; d, d, d, several thoracic and lumbar lymphatic glands; h, h, a short portion of the esophagus. Two azygous veins run parallel with and on each side of the duct, until the left crosses behind the duct to join the right. The structures represented rest nearly upon the back-bone." -Whitney, 1911

Thoracic Duct

"Human Thoracic Duct and Azygous Veins. a, receptacle of the chyle; b, trunk of the thoracic duct, opening…

Principal forms of the isometric system: octahedron.

Octahedron

Principal forms of the isometric system: octahedron.

Principal forms of the isometric system: trigonal trisoctahedron.

Trigonal Trisoctahedron

Principal forms of the isometric system: trigonal trisoctahedron.

Principal forms of the isometric system: tetragonal trisoctahedron.

Tetragonal Trisoctahedron

Principal forms of the isometric system: tetragonal trisoctahedron.

Principal forms of the isometric system: hexoctahedron.

Hexoctahedron

Principal forms of the isometric system: hexoctahedron.

An illustration of the reproductive system of a female earthworm which is located in the eleventh to the fourteenth segment. "sp. o, its external orifice; sp. sac, spermathecal sac; av, sac containing ovary; r.o, egg; od, oviuct." (Britannica. 1910)

Female Earthworm Reproductive System

An illustration of the reproductive system of a female earthworm which is located in the eleventh to…

Principal forms of the isometric system: dodecahedron.

Dodecahedron

Principal forms of the isometric system: dodecahedron.

Principal forms of the isometric system: tetrahexahedron.

Tetrahexahedron

Principal forms of the isometric system: tetrahexahedron.

Principal forms of the isometric system: rectangular prism.

Rectangular Prism

Principal forms of the isometric system: rectangular prism.

Principal forms of the isometric system: tetrahedron.

Tetrahedron

Principal forms of the isometric system: tetrahedron.

Principal forms of the isometric system: deltohedron

Deltohedron

Principal forms of the isometric system: deltohedron

Principal forms of the isometric system: tristetrahedron.

Tristetrahedron

Principal forms of the isometric system: tristetrahedron.

An enlargement of the reproductive organs of a earthworm. "sp, Spermatheca; sp',Spermathecal sac involving the last; ov, Ovary; r.o. Egg sac; od, Oviduct." (Britannica, 1910)

Female Earthworm Reproductive System

An enlargement of the reproductive organs of a earthworm. "sp, Spermatheca; sp',Spermathecal sac involving…

Principal forms of the isometric system: hextetrahedron.

Hextetrahedron

Principal forms of the isometric system: hextetrahedron.

Principal forms of the isometric system: pyritohedron.

Pyritohedron

Principal forms of the isometric system: pyritohedron.

Principal forms of the hexagonal system: hexagonal pyramid.

Hexagonal Pyramid First Order

Principal forms of the hexagonal system: hexagonal pyramid.

Principal forms of the hexagonal system: hexagonal pyramid.

Hexagonal Pyramid Second Order

Principal forms of the hexagonal system: hexagonal pyramid.

Principal forms of the hexagonal system: dihexagonal pyramid.

Dihexagonal Pyramid

Principal forms of the hexagonal system: dihexagonal pyramid.