Biogenesis
Encyclopedia
Biogenesis is the law that living things come only from other living things, e.g. a spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

 lays eggs, which develop into spiders. It may also refer to biochemical processes of production in living organisms.

Spontaneous generation

The ancient Greeks believed that living things could spontaneously come into being from nonliving matter, and that the goddess Gaia
Gaia (mythology)
Gaia was the primordial Earth-goddess in ancient Greek religion. Gaia was the great mother of all: the heavenly gods and Titans were descended from her union with Uranus , the sea-gods from her union with Pontus , the Giants from her mating with Tartarus and mortal creatures were sprung or born...

 could make life arise spontaneously from stones – a process known as Generatio spontanea. Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

 disagreed, but he still believed that creatures could arise from dissimilar organisms or from soil. Variations of this concept of spontaneous generation still existed as late as the 17th century, but towards the end of the 17th century, a series of observations and arguments began that eventually discredited such ideas. This advance in scientific understanding was met with much opposition, with personal beliefs and individual prejudices often obscuring the facts.

Francesco Redi
Francesco Redi
Francesco Redi was an Italian physician, naturalist, and poet.-Biography:The son of Gregorio Redi and Cecilia de Ghinci was born in Arezzo on February 18, 1626. After schooling with the Jesuits, he attended the University of Pisa...

, an Italian physician, proved as early as 1668 that higher forms of life did not originate spontaneously, but proponents of abiogenesis
Abiogenesis
Abiogenesis or biopoesis is the study of how biological life arises from inorganic matter through natural processes, and the method by which life on Earth arose...

 claimed that this did not apply to microbes and continued to hold that these could arise spontaneously. Attempts to disprove the spontaneous generation of life from non-life continued in the early 19th century with observations and experiments by Franz Schulze and Theodor Schwann
Theodor Schwann
Theodor Schwann was a German physiologist. His many contributions to biology include the development of cell theory, the discovery of Schwann cells in the peripheral nervous system, the discovery and study of pepsin, the discovery of the organic nature of yeast, and the invention of the term...

.
In 1745, John Needham
John Needham
John Turberville Needham FRS was an English biologist and Roman Catholic priest.He was first exposed to natural philosophy while in seminary school and later published a paper which, while the subject was mostly about geology, described the mechanics of pollen and won recognition in the botany...

 added chicken broth to a flask and boiled it. He then let it cool and waited. Microbes grew, and he proposed it as an example of spontaneous generation. In 1768, Lazzaro Spallanzani
Lazzaro Spallanzani
Lazzaro Spallanzani was an Italian Catholic priest, biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and essentially discovered echolocation...

 repeated Needham's experiment but removed all the air from the flask. No growth occurred. In 1854, Heinrich Schröder (1810–1885) and Theodor von Dusch
Theodor von Dusch
Theodor von Dusch was a German physician who was the native of Karlsruhe. He was the son of Baden statesman Alexander von Dusch ....

, and in 1859, Schröder alone, repeated the Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...

 filtration experiment and showed that living particles can be removed from air by filtering it through cotton-wool.

In 1864, Louis Pasteur
Louis Pasteur
Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...

 finally announced the results of his scientific experiments. In a series of experiments similar to those performed earlier by Needham and Spallanzani, Pasteur demonstrated that life does not arise in areas that have not been contaminated by existing life. Pasteur's empirical results were summarized in the phrase Omne vivum ex vivo, Latin for "all life [is] from life".

Law of Biogenesis

The Law of Biogenesis, attributed to Louis Pasteur
Louis Pasteur
Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...

, states that life arises from pre-existing life, not from nonliving material. Pasteur's (and others) empirical results were summarized in the phrase Omne vivum ex vivo, Latin for "all life [is] from life", also known as the "law of biogenesis". Pasteur stated: "La génération spontanée est une chimère" ("Spontaneous generation is a dream").
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