Encyclopedian Dictionary

Ameba or Amoeba

The most common form of ameba is the Ameba proteus, named from the mythological Greek sea god, Proteus, who could change his shape at will.

An Ameba
Taxonomic Hierarchy
Kingdom	Protozoa
Phylum	Protozoa
Subphylum	Sarcodina
Superclass	Rhizopoda
Class	Lobosa – amoebas, amibes
Direct Children:
Order	Amoebida
Order	Arcellinida
Order	Euamoebida

The simplest of all the microscopic, single cell lifeforms. Once classed as an animal, the protozoa are now classified in the Kingdom Protozoa. The Amoebae form a group of single cell organisms called Protozoa or Protista.

Protozoa means "first animals". Protozoa also share many similar characteristics with plants, such as photosynthesis among some species, so the term Protista meaning "first creatures" is often used.

The name amoeba is not exclusively applied to members of the genus Amoeba but to a range of different types of Protista with pseudopodia. Some live in salt water, others in fresh water, perhaps on wet stems of plants which grown around wet environments. Others thrive in damp soil and others as parasitic in bodies of animals. They include some with shells, like Arcella, and also the half-dozen species that live in the human mouth and digestive system. One of these species is the cause of amoebic dysentery (Entamoeba). Some amoebae contain several nuclei which includes the large Chaos chaos, which may become six times the length of Amoeba proteus, which probably is the most well known species.

The amoeba's cell body is of an indefinate shape, changing constantly as it moves by means of pseudopodia (meaning "false feet"). The endoplasm is thrust outward from any point of its cell body, the liquid protoplasm (life material) within flows slowly into them. Afterward the rest of the cell contracts behind, creating motion and forward movement. Its basic structure consists of a thin, elasticized external membrane which holds the protoplasm safely inside the cell. Directly inside the membrane is a narrow layer of clear material, or ectoplasm, which aides in the cell's ability to possess form. Ectoplasm surrounds the main body mass of granular ectoplasm, which is differentiated into a more solid outer portion, the plasmagel, and more fluid inner portion, the plasmasol. Contained within the endoplasm is the roughly spherical nucleus which are associated with life fuctions of the cell.

Ameba Side View on Slide
An Ameba from Side View on Microscope Slide
This is a diagram of what was captured under a modern microscope. This side view, appears to be of an amoeba moving to the right with an extended "false foot", (or pseudopodium) and seemingly elevated on small protoplasmic pegs.

The ameba's body consists of a single cell which outermost film is called the cell membrane. This encloses a semi-liquid substance called cytoplasm, which is a special form of protoplasm. Though the ameba has no permanenly definitive shape, it does have a permanent hind end and forms its pseudopodium in a characteristic pattern, depending on the species.

Within the cytoplasm the following are included

a vacuole or spherical liquid-containing space which regulates water content and pressure and aides in regulation of the excretion of some liquid wastes.
a spherical, central mass called the nucleus, which regulates vital functions of the cell
granules of variegated substances Food vacuoles enclose whatever the ameba has consumed.

The ameba was once classified among the animal kingdom because it feeds, excretes, respires and reproduces in many of the same fundamental ways that many animals do, not excluding man.

It feeds mainly on other protista, algae and bacteria, by utilizing its pseudopodia to surround and engulf a food particle. Water is engulfed with the food and the two form a vacuole within the cytoplasm. Digestion is a similar process to that which occurs with most other organisms, that is, digestive fluids are secreted into the food vacuole and digestible portions broken down and absorbed. The particle is digested within the vacuole and asorbed into the cell. This process is known as phagocytosis, which comes from Greek meaning, "eating by cells".
The contractile vacuole, bubblelike in appearance regulates water in the cell and may also serve the function of excretion. Food vacuoles are formed as the ameba ingest nutrients. Food vacuoles become smaller as digestion proceeds until the unused residue is excreted and vacuole disappears.

Excretion is accomplished through the cell membrane by osmosis (the passage of a liquid through a semi-permeable membrane) and perhaps also by the contractile vacuole that regulates water pressure. The Ameba discards fecal materials by merely flowing away from indigestible particles.

Respiration is achieved through osmosis as well. The ameba takes oxygen from surrounding water and releases carbon dioxide by a reverse process.

Reproduction is accomplished by the cell dividing into two equal halves of a whole, mature ameba which has reached maximum size. During this process, elements of the nucleus separate into identical halves, which insure the chromatin of the nucleus is evenly divided between the two resulting individuals. This process is called binary fission and takes less than an hour to complete. It is the usual method of reproduction. The chromatin of the nucleus likely carry the genetic and heredity factors. This complicated process which results in successfully dividing a single chromosome into two individuals is called mitosis.
The entire reproduction process begins with the amoeba becoming spherical in shape and the nucleus divides into two, the halves move apart, then the cell splits down the center.
Sometimes Amoeba proteus reproduce differently. The nucleus divides into hundreds of smaller ones which become surrounded by cytoplasm and a protective wall. All this takes place in the original single cell. These cysts can survive through droughts but also serve the purpose of transplant into new locations. Large cysts are formed when the whole cell surrounds itself with a thick shell. Some species of Amoeba do reproduce sexually.

If threatened the ameba has the ability to form a tiny spherical shaped droplet, and if the water supply in its environment is evaporated, it secretes about its body a thick impervious shell, called a cyst. While in this state it is able to withstand death by desiccation until the availability of more favorable environmental conditions. Encysted amebas can be carried by wind and therefore are widely distributed. Other protozoans are also known to use this same survival mechanism.

The average ameba is between 5 to 200 microns in diameter or an average size of about 1/1000th of an inch. The largest amebas are only about twice the diameter of a coarse human hair. The smallest species may be about 1/20th of the same hair. Amoeba proteus, measures ½ mm., and is just large enough to be visible to the naked eye.

There are many known species, some of which are:

A. proteus
A. limax, called limax because its body takes on the form of a slug
A. guttula, a notably small species

Amebas are not only free-roaming, but some are parastic in both humans, animals and plants. Some are harmless whilst others may cause serious disease or potentially fatal. One serious human parasite is Endamoeba histolytica which lives in the intestine and is the cause of amebic dysentery. See Amebiasis. Once considered serious but now is readily controlled by drugs, such as an alkaloid called emetine, derived from ipecac.

These creatures, protozoa, named so as "first animals," consist of but a single cell and may serve as a glimpse, an insight into what possibly may have been the first animals to inhabit the planet, and give some indication as to what kind of common ancestor in the past gave rise to all living things.

Some permissible variations on spelling include

amoeba
amœba
endamoeba
entamœba

Classification of Amoeba proteus from itis.gov, Amoeba proteus (Pal.), Taxonomic Serial No.: 43854 Diagram of Amoeba proteus Amoeba proteus
Taxonomic Hierarchy
Kingdom	Protozoa
Phylum	Protozoa
Subphylum	Sarcodina
Superclass	Rhizopoda
Class	Lobosa – amoebas
Order	Amoebida
Family	Amoebidae
Genus	Amoeba Ehrenberg, 1930
Species	Amoeba proteus (Pal.)

References and Further Reading

Ameba, Definition

Lobosa, Taxonomic Serial No.: 43850

Protozoa, Definition

Wilhelm Fabricius Hildanus (1560-1634)

Hildanus Fabricius
Wilhelm Fabricius Hildanus
Source: U.S. National Library of Medicine, History of Medicine Division

Wilhelm Fabricius Hildanus [fə-brĭsh′əs hĭl-dā′nəs] also known by the name, Wilhelm Fabry of Hilden, German physician and called "The father of German surgery."

Among his numerous contributions to medicine were the first classification of burns, the introduction of the tourniquet in surgical practice and extraction of iron splinters in the eye with use of a magnet.

References and Further Reading

U.S. National Library of Medicine, History of Medicine Division

Venus Flytrap ( Dionaea muscipula, J. Ellis )

Venus Flytrap, also known as Venus's Flytrap

The Venus Flytrap is among a group of plants known as Carnivorous plants. There are various types of carnivorous plants, including flowering plants and fungi which prey and feed upon small animals and insects. Such species are sometimes referred to as insectivorous plants.

Governor Arthur Dobbs of North Carolina was the first person to describe the plant. He named it "Fly Trap Sensitive". In 1760 he communicated about the discovery of the plant's peculiar ability to close and trap objects, to Mr. P. Collinson of England. Later, Mr. J. Bartram of Philadelphia sent specimens known to him as "Tipitiwitchet," to Mr. P. Collinson. The species was first described among the scientific community in 1768 by the American botanist J. Ellis in letters to Linnaeus providing a substantial description of the structure and functions of the leaves, suggesting even the insectivorous nature of the species. Linnaeus declared it the most wonderful of plants, Miraculum Naturae. Linnaeus presumed the plant exhibited extreme sensitivity, in which insects were accidentally captured and subsequently allowed to escape.

"But the plant, of which I now enclose you an exact figure, with a specimen of its leaves and blossoms, shews, that nature may have some view towards nourishment, in forming the upper joint of the leaf like a machine to catch food: upon the middle of this lies the bait for the unhappy insect that becomes its prey. Many minute red glands, cover its inner surface, and which perhaps discharge sweet liquor, tempt the poor animal to taste them; and the instant these tender parts are irritated by its feet, the two lobes rise up, grasp it fast, lock the row of spines together and squeeze it to death. And, further, lest the strong efforts for life, in the creature thus taken, should serve to disengage it, three small erect spines are fixed near the middle of each lobe, among the glands, that effectually put an end to all its struggles. Nor do the lobes ever open again, while the dead animal continues there."

The letter which contained inaccuracies did not convince Linnaeus of the plant's carnivorous nature, he believed rather, that the insects were released, and trapped merely due to oversensitivity, being such the case with Mimosa pudica.

Ellis arrived at incorrect conclusions about the functions in the plant, including the three erect spines which were later discovered to be trigger hairs on the inner surface of the trap, and a view shared by Erasmus Darwin, botanist and grandfather of Charles Darwin, who wrote,

"In the Dionaea muscipula there is a still more wonderful contrivance to prevent the depredations of insects: the leaves are armed with long teeth, like the antennae of insects, and lie spread upon the ground around the stem, and are so irritable, that when an insect creeps upon them they fold up and crush or pierce it to death."

However the insectivorous nature of the plant was more elaborately investigated by Charles Darwin and described in his book, Insectivorous Plants (1875).

Charles Darwin observed the plant during its digestive state, noting the abundance of the secreted fluid. Making a small opening at the base of one lobe which contained a large crushed fly, the secretion continued to run down the rootstalk a total of nine days, during which the plant was under steady observation.

The required time for digestion is approximately ten days to complete, after which the leaf reopens. Each leaf, or trap, can capture an average of three or four insects during its life span after which it ceases to function. Otherwise, when the trap has been triggered without successful capture of prey it can open and close many more times.

Ellis named the plant Dionaea. The origin of the name Dionaea has its origin in Greek and Roman mythology. In Greek, Dione is the mother of Aphrodite and at times used as an alternative name for the goddess of love. To the Romans, Venus was the goddess of love.

The Venus Flytrap is a native perennial found near the borders of coastal North and South Carolina around swampy bogs. Seldom ever does the flytrap survive well after relocation from its wet native habitat. Often flytraps are found in the presence of other carnivorous plants such as Sundews, Butterworts, Bladderworts and Pitcher Plants. The flytraps inhabit relatively level areas, and tend not to be found where depressions lie due to excess water. They thrive in damp soil, although it has been observed that during relatively dry periods there is no apparent harm to the plants.

Several methods are employed among carnivorous plants to trap their prey. Venus Flytrap's method is different from many other carnivorous plants and referred to as a "Mechanical Trap," specifically a "snap trap". Each leaf has two lobes, standing at rather less than a right angle to each other. The typical angle formed by the lobes is 40 to 50 degrees.

The upper surfaces are covered with minute circular sessile glands. The prey is trapped by rapid closure of the lobes around the insect when it touches one of the three sensory hairs, or fine-pointed bristles. In rare instances there may be as many as four trigger hairs on each surface. The trap has been compared to a hinge but this is inaccurate because a hinge has an articulated joint. The trap has none. It is equipped with bristles that are sometimes referred to as cilia. There are two types of glands,

Alluring glands, which produce a sugary substance which has a pleasant odor to attract insects and arranged along the outside margins of the trap. It has been argued that this arrangement is by design to prevent the smallest insects from tripping closure of the trap, conserving the plant's effort and energies for more desirable prey. Therefore, any insect which is less than ¼ inch in length is too short, but can freely dine on the nectar. In the event a small insect has triggered closure and escapes, the trap will reopen after about a 24 hour period.
Digestive-absorptive glands, are conspicuously red in coloration due to a pigment present in the cell fluid: Anthocyanin. If the prey that becomes imprisoned is the correct size for the trap, digestion will occur without any decay. However, the formic acid present in the digestive secretions and process is believed to be a bactericide. Inappropriate objects, such as fat which is placed in the trap, will cause the trap to turn black and decay instead of opening. However, the death of a trap does not spell demise for the entire plant as new traps are in the process of forming during the growing season (70°-100°F), at the base of the rosette.

The glands are structurally identical. Observations indicate the trap will not close unless a single trigger hair is stimulated at least twice, or two hairs stimulated simultaneously or in close succession of 1 to 20 seconds.

This reaction, snapping shut and the leaf closing around the insect, occurs in about half a second in normal daytime temperatures. The spikes interlock, and the insect is trapped. After suitable prey is captured, within thirty minutes a narrowing phase begins in which the lobes become tightly pressed together and the outline of captured prey is visible while soft-bodied insects are crushed. This is followed by the release of digestive enzymes within the trap's interior whilst a protective seal is produced just below the marginal spines. If the insect has not been crushed by the lobes, it is likely the insect drowns in the digestive fluids.

The leaf then forms what may be referred to as a "temporary stomach" of sorts. With the insect imprisoned, the Flytrap's glands pour out a red acidic secretion or "sap" containing an enzyme that will dissolve the soft body parts. This digestive enzyme is similar to that which is produced by the leaves of the Sundew plant.

The Venus Flytrap grows from a bulb-like rootstalk and bears slender flower stalks which reach about a foot in height, producing a corymbs of white flowers which sprout in May and bloom in June. The stalk may bear between 1-15 white flowers. Each flower consists of 5 green sepals, 5 white petals, typically 15 stamens and 1 compound pistil. The leaves grow two to eight inches long and located at the base of the plant in a spreading rosette.

During the changing seasons the plant takes on varying characteristics. During the spring, leaves tend to be green with broad petioles which lateral extensions are referred to as "wings". Red coloration is limited or absent, if it is present, it is restricted to the glands on the inner surface of the traps. When late spring becomes summer, the spring leaves are terminated by flowering. When flowering has completed, the summer leaves are produced which are as long or longer, much more narrow and almost wingless. The summer leaves produce the largest traps which tend to grow vertically. With the onset of fall, winter-like leaves are produced which are the smallest. Frost may kill the leaves during the winter. Those which survive winter, tend to be prostrate and about the size of spring to summer leaves.

The bright red coloration in some flytraps seems to be influenced by its exposure to light. Though genetic factors play a role, flytraps thrive well in intense light with most of the plants developing the deep red maroon coloration in the traps, however, when there is insufficient lighting, the plants tend to develop with less healthy characteristics and remain a green pigmentation throughout. Although light contributes to their overall preferred health, direct sunlight is discouraged when cultivated in enclosed containers.

Venus Flytrap is the only known species in the genus Dionaea, therefore making it monotypical.

Kingdom	Plantae – plants
Subkingdom	Viridaeplantae – green plants
Infrakingdom	Streptophyta – land plants
Division	Tracheophyta – vascular plants
Subdivision	Spermatophytina – seed plants
Infradivision	Angiospermae – flowering plants
Class	Magnoliopsida
Superorder	Caryophyllanae
Order	Caryophyllales
Family	Droseraceae – sundews
Genus	Dionaea (J. Ellis) – Venus flytrap, Venus fly trap
Species	Dionaea muscipula (J. Ellis) – Venus fly trap, Venus flytrap

References and Further Reading

Charles Darwin, Insectivorous Plants, 1875

M. Shene, Biology of Flowering Plants, 1924

ITIS.gov, Taxonomical Database

Venus Flytrap

American Grayling ( Thymallus arcticus )

American Grayling
Thymallus arcticus.

The American Grayling's is a small fresh water fish of the salmon family and genus Thymallus, common in northern streams and distinguished by its dorsal fin which is disproportionately large in ratio to its body size. The dorsal fin contains between 13 to 23 rays.

The appearance of the fish is often in dispute from various sources, depending on factors which are influenced by its diet and food supply including lighting at a given time. The Grayling has a small mouth with few teeth, and feeds on insects. Some have stated its coloring is lavender while others might say its green, others claim it is gold, bronze or silver in coloration. Some sources claim the Graying has the appearance of a Rocky Mountain whitefish and half trout, which is fairly accurate due to its whitefish body and trout head and mouth. However, the Graying's overall coloration is what makes it memorable.

Primarily the distinguishing features are silvery with a limited number of black spots speckling its sides, mostly on the forward half of the body. Except for the spotted dorsal fin which is distinctively colored, all the fins are usually dark. Like some fish with silvery coloration, they reflect the colors that are nearby.

Graylings rarely get very large. However in the Canadian Northwest, some American Graylings reach up to 1.5 to 3 pounds as a general estimate. The male grows larger than females. The male's dorsal fin is larger than the female, it is small and rounded in the front and rises to a peak toward the end of the fin. The dorsal fin of the female begins tall and tapers off.

Graylings are commonly found in Alaska, Montana, Wyoming, Utah and Idaho. Some other states have transplanted this species, but populations are limited.

Europeans are more familiar with the European Grayling which is widely distributed in the frigid lakes and streams, and often considered to be more the sporting fish, than the American counterpart, as it is a highly esteemed fish in European waters located in the Alpine regions of France, Germany, Austria and Italy. Both American and European Graylings share the same family, but are entirely different species. Two fish that are referred to at times, the Montana Grayling (Thymallus montanus) and Michigan Grayling (Thymallus tricolor) are likely sub-species of the American Grayling. The only populations native to the lower 48 states were in Michigan and Montana, and the Michigan population is now extinct. Another North American species is the Alaska Grayling (Thymallus signifer) found in Alaska and Canada.

Kingdom	Animalia – Animal
Phylum	- Chordata
Subphylum	Vertebrata – vertebrates
Superclass	Osteichthyes – bony fishes
Class	Actinopterygii – ray-finned fishes, spiny rayed fishes
Subclass	Neopterygii – neopterygians
Infraclass	Teleostei
Superorder	Protacanthopterygii
Order	Salmoniformes – salmons
Family	Salmonidae – salmonids, trouts and salmons
Subfamily	Thymallinae
Genus	Thymallus (Linck, 1790 – graylings)
Species	Thymallus arcticus (Pallas, 1776), Arctic grayling, ombre arctique
*Direct Children*:
Subspecies	Thymallus arcticus arcticus (Pallas, 1776)
Subspecies	Thymallus arcticus baicalensis (Dybowski, 1874)–baikal graying
Subspecies	Thymallus arcticus pallasi (Valenciennes in Cuvier and Valenciennes, 1848) –east siberian grayling

References

Arctic Grayling - Thymallus arcticus

A Field Guide to Fly Fishing by Dennis Bitton

Thymallus arcticus, (Pallas, 1776) Taxonomic Serial No.: 162016

Johann Ludwig Faber (17th Century) Glassmaker

Beaker with View of Kraftshof near Nuremberg. Clear glass, black enamel painting. Summary: In the mid-17th century Johann Schaper of Nuremberg transferred the black vitreous painting technique known from stained-glass painting to hollow glassware and ceramic materials. He and a number of successors decorated glasses and faiences in this manner, often with coats-of-arms, vistas and townscapes, and mythological scenes. Today they are known as 'Hausmaler', because in contrast to their colleagues who were employed in manufactories they worked at home and on their own account.
Johann Ludwig Faber

Johann Ludwig Faber
17th Century German glass maker.

References

Flashback: Hausmaler Decoration on Fayence and Porcelain

Glas mit Ansicht von Kraftshof bei Nürnberg (Kugelfußbecher)

Goblet and cover, Johann Ludwig Faber, 1690. Museum no. 1835-1855

fabrikoid

Pronunciation key
(fab′ri-koid′)

fab•ri•koid n.

A fabric with cloth base but pyroxylin surface, inpervious to water or other fluid.
A fabric made to resemble leather, used for upholstery, etc.
A trademark or tradename.

"Fabrikoid was one of DuPont’s first non-explosives products. Produced by coating fabric with nitrocellulose and marketed as artificial leather, Fabrikoid was widely used in upholstery, luggage and bookbindings during the early 20th century. In the 1920s, Fabrikoid became the preferred material for automobile convertible tops and seat covers."

References

Artificial Leather : 1910

Fabricius ab Aquapendente, Geronimo Fabrici (1537-1619) Anatomist

Fabricius ab Aquapendente

Geronimo Fabrici, Girolamo Fabrizio or Fabrizi (Hieronymus Fabricius ab Aquapendente)

Born May 20, 1537 in Aquapendente, Italy. Died May 21, 1619 in Padua, Italy.

An outstanding surgeon and Renaissance anatomist which helped found modern embryology. The majority of his life was spent at the University of Padua where after a course of philosophy, he studied medicine under the anatomist Gabriel Fallopius. As successor to Fallopius to the chair of surgery and anatomy (1562-1613), Fabricius built a reputation that attracted students from all over Europe.

Among his pupils there was the English anatomist, William Harvey, who later elaborated the circulation of the blood. In De Venarum Ostiolis (1603); "On the Valves of the Veins," Fabricius gave the first clear description of the semilunar valves of the veins, which later provided Harvey with a crucial point in his famous argument for circulation of the blood.

Fabricius' De Formato Foetu (1600); "On the Formation of the Fetus", summarizing his investigations of the fetal development of many animals, including man, contained the first detailed description of the placenta and opened the field of comparative embryology. He also gave the first full account of the larynx as a vocal organ and was first to demonstrate that the pupil of the eye changes its size.

When he gave up his chair of surgery in 1609, Fabricius maintained a large practice so that he might continue to develop improved surgical techniques. His Opera Omnia Anatomica et Physiologica "Complete Anatomical and Physiological Works" was first published in 1625.

References

Girolamo Fabrici, AKA Hieronymus Fabricius ab Aquapendente

Fabricius, ab Aquapendente, ca. 1533-1619