experiment de spallanzani

• History & Society
• Science & Tech
• Biographies
• Animals & Nature
• Geography & Travel
• Arts & Culture
• Games & Quizzes
• On This Day
• One Good Fact
• New Articles
• Lifestyles & Social Issues
• Philosophy & Religion
• Politics, Law & Government
• World History
• Health & Medicine
• Browse Biographies
• Birds, Reptiles & Other Vertebrates
• Bugs, Mollusks & Other Invertebrates
• Environment
• Fossils & Geologic Time
• Entertainment & Pop Culture
• Sports & Recreation
• Visual Arts
• Demystified
• Image Galleries
• Infographics
• Top Questions
• Britannica Kids
• Saving Earth
• Space Next 50
• Student Center

• Why is biology important?

Lazzaro Spallanzani

Our editors will review what you’ve submitted and determine whether to revise the article.

• The Embryo Project Encyclopedia - Biography of Lazzaro Spallanzani
• Lazzaro Spallanzani - Student Encyclopedia (Ages 11 and up)

Lazzaro Spallanzani (born Jan. 12, 1729, Modena , Duchy of Modena—died 1799, Pavia, Cisalpine Republic) was an Italian physiologist who made important contributions to the experimental study of bodily functions and animal reproduction . His investigations into the development of microscopic life in nutrient culture solutions paved the way for the research of Louis Pasteur .

Spallanzani was the son of a distinguished lawyer. He attended the Jesuit college at Reggio, where he received a sound education in the classics and philosophy. He was invited to join the order, but, although he was eventually ordained (in 1757), he declined this offer and went to Bologna to study law. Under the influence of his kinswoman Laura Bassi , a professor of mathematics , he became interested in science . In 1754 Spallanzani was appointed professor of logic , metaphysics , and Greek at Reggio College and in 1760 professor of physics at the University of Modena.

Although Spallanzani published in 1760 an article critical of a new translation of the Iliad, all of his leisure was being devoted to scientific research. In 1766 he published a monograph on the mechanics of stones that bounce when thrown obliquely across water. His first biological work, published in 1767, was an attack on the biological theory suggested by Georges Buffon and John Turberville Needham , who believed that all living things contain, in addition to inanimate matter, special “ vital atoms ” that are responsible for all physiological activities. They postulated that, after death, the “vital atoms” escape into the soil and are again taken up by plants. The two men claimed that the small moving objects seen in pond water and in infusions of plant and animal matter are not living organisms but merely “vital atoms” escaping from the organic material. Spallanzani studied various forms of microscopic life and confirmed the view of Antonie van Leeuwenhoek that such forms are living organisms. In a series of experiments he showed that gravy, when boiled, did not produce these forms if placed in phials that were immediately sealed by fusing the glass. As a result of this work, he concluded that the objects in pond water and other preparations were living organisms introduced from the air and that Buffon’s views were without foundation.

The range of Spallanzani’s experimental interest expanded. The results of his regeneration and transplantation experiments appeared in 1768. He studied regeneration in a wide range of animals including planarians, snails, and amphibians and reached a number of general conclusions: the lower animals have greater regenerative power than the higher; young individuals have a greater capacity for regeneration than the adults of the same species; and, except in the simplest animals, it is the superficial parts not the internal organs that can regenerate. His transplantation experiments showed great experimental skill and included the successful transplant of the head of one snail onto the body of another. In 1773 he investigated the circulation of the blood through the lungs and other organs and did an important series of experiments on digestion , in which he obtained evidence that digestive juice contains special chemicals that are suited to particular foods. At the request of his friend Charles Bonnet , Spallanzani investigated the male contribution to generation . Although the spermatozoa had first been seen in the 17th century, their function was not understood until some 30 years after the formulation of the cell theory in 1839. As a result of his earlier investigations into simple animals, Spallanzani supported the prevailing view that the spermatozoa were parasites within the semen . Both Bonnet and Spallanzani accepted the preformation theory . According to their version of this theory, the germs of all living things were created by God in the beginning and were encapsulated within the first female of each species. Thus, the new individual present in each egg was not formed de novo but developed as the result of an expansion of parts the delineation of which had been laid down within the germ by God at the creation. It was assumed that the semen provided a stimulus for this expansion, but it was not known if contact was essential nor if all the parts of the semen were required. Using amphibians, Spallanzani showed that actual contact between egg and semen is essential for the development of a new animal and that filtered semen becomes less and less effective as filtration becomes more and more complete. He noted that the residue on the filter paper retained all its original power if it were immediately added to the water containing the eggs. Spallanzani concluded that it was the solid parts of the secretion, proteinaceous and fatty substances that form the bulk of the semen, that were essential, and he continued to regard the spermatozoa as inessential parasites. Despite this error, Spallanzani performed some of the first successful artificial insemination experiments on lower animals and on a dog.

As Spallanzani’s fame grew, he became a fellow of most of the scientific societies in Europe. In 1769 he accepted a chair at the University of Pavia , where, despite other offers, he remained for the rest of his life. He was popular with students and colleagues. Once a small group, jealous of his success, accused him of malpractice in association with the museum that he controlled, but he was soon vindicated . Spallanzani took every opportunity to travel, to study new phenomena, and to meet other scientists. The accounts of his journeys to Constantinople and Sicily still provide interesting reading. Toward the end of his life he conducted further research on microscopic animals and plants that he had started early in his career; he also began studies on the electric charge of the torpedo fish and sense organs in bats. In his last set of experiments, published posthumously, he attempted to show that the conversion of oxygen to carbon dioxide must occur in tissues, not in the lungs (as Antoine-Laurent Lavoisier had suggested in 1787).

3.1 Spontaneous Generation

Learning objectives.

By the end of this section, you will be able to:

• Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms
• Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation

Clinical Focus

Barbara is a 19-year-old college student living in the dormitory. In January, she came down with a sore throat, headache, mild fever, chills, and a violent but unproductive (i.e., no mucus) cough. To treat these symptoms, Barbara began taking an over-the-counter cold medication, which did not seem to work. In fact, over the next few days, while some of Barbara’s symptoms began to resolve, her cough and fever persisted, and she felt very tired and weak.

• What types of respiratory disease may be responsible?

Jump to the next Clinical Focus box

Humans have been asking for millennia: Where does new life come from? Religion, philosophy, and science have all wrestled with this question. One of the oldest explanations was the theory of spontaneous generation, which can be traced back to the ancient Greeks and was widely accepted through the Middle Ages.

The Theory of Spontaneous Generation

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation , the notion that life can arise from nonliving matter. Aristotle proposed that life arose from nonliving material if the material contained pneuma (“spirit” or “breath”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. 1

This theory persisted into the 17th century, when scientists undertook additional experimentation to support or disprove it. By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared. Jan Baptista van Helmont , a 17th century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse populations to flourish.

However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), performed an experiment in 1668 that was one of the first to refute the idea that maggots (the larvae of flies) spontaneously generate on meat left out in the open air. He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Redi left meat in each of six containers ( Figure 3.2 ). Two were open to the air, two were covered with gauze, and two were tightly sealed. His hypothesis was supported when maggots developed in the uncovered jars, but no maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies, not the product of spontaneous generation.

In 1745, John Needham (1713–1781) published a report of his own experiments, in which he briefly boiled broth infused with plant or animal matter, hoping to kill all preexisting microbes. 2 He then sealed the flasks. After a few days, Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures. He argued that the new microbes must have arisen spontaneously. In reality, however, he likely did not boil the broth enough to kill all preexisting microbes.

Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth. 3 As in Needham’s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani’s results contradicted the findings of Needham: Heated but sealed flasks remained clear, without any signs of spontaneous growth, unless the flasks were subsequently opened to the air. This suggested that microbes were introduced into these flasks from the air. In response to Spallanzani’s findings, Needham argued that life originates from a “life force” that was destroyed during Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation ( Figure 3.3 ).

Check Your Understanding

• Describe the theory of spontaneous generation and some of the arguments used to support it.
• Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.

Disproving Spontaneous Generation

The debate over spontaneous generation continued well into the 19th century, with scientists serving as proponents of both sides. To settle the debate, the Paris Academy of Sciences offered a prize for resolution of the problem. Louis Pasteur , a prominent French chemist who had been studying microbial fermentation and the causes of wine spoilage, accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a “life force” to the broth but rather airborne microorganisms.

Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks), in which he boiled broth to sterilize it ( Figure 3.4 ). His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. However, should the necks be broken, microorganisms would be introduced, contaminating the flasks and allowing microbial growth within the broth.

Pasteur’s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “ Omne vivum ex vivo ” (“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that “…life is a germ and a germ is life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” 4 To Pasteur’s credit, it never has.

• How did Pasteur’s experimental design allow air, but not microbes, to enter, and why was this important?
• What was the control group in Pasteur’s experiment and what did it show?
• 1 K. Zwier. “Aristotle on Spontaneous Generation.” http://www.sju.edu/int/academics/cas/resources/gppc/pdf/Karen%20R.%20Zwier.pdf
• 2 E. Capanna. “Lazzaro Spallanzani: At the Roots of Modern Biology.” Journal of Experimental Zoology 285 no. 3 (1999):178–196.
• 3 R. Mancini, M. Nigro, G. Ippolito. “Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.” Le Infezioni in Medicina 15 no. 3 (2007):199–206.
• 4 R. Vallery-Radot. The Life of Pasteur , trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142.

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute OpenStax.

Access for free at https://openstax.org/books/microbiology/pages/1-introduction

• Authors: Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster
• Publisher/website: OpenStax
• Book title: Microbiology
• Publication date: Nov 1, 2016
• Location: Houston, Texas
• Book URL: https://openstax.org/books/microbiology/pages/1-introduction
• Section URL: https://openstax.org/books/microbiology/pages/3-1-spontaneous-generation

© Jul 18, 2024 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.

Lazzaro Spallanzani (1729-1799)

Lazzaro Spallanzani’s imaginative application of experimental methods, mastery of microscopy, and wide interests led him to significant contributions in natural history, experimental biology, and physiology. His detailed and thoughtful observations illuminated a broad spectrum of problems ranging from regeneration to the genesis of thunderclouds.

Born in the small town of Scandiano in northern Italy on 10 January 1729, Spallanzani grew up in a large, wealthy family and attended local schools until he was fifteen. He then studied at a Jesuit seminary in Reggio Emilia where his intellectual abilities earned him the nickname “the astrologer.” He matriculated in 1749 at the University of Bologna and began working toward a degree in jurisprudence. His love for the natural sciences and mathematics soon led him to change his focus to philosophy, in which he earned his doctorate in 1754. His philosophical studies encompassed metaphysics and theology, which prepared him to take minor orders and be ordained as a priest in the Roman Catholic Church. Spallanzani’s affiliation with the Church provided financial support, but more importantly offered protection from the Italian Inquisition, which often censored work deemed contrary to Catholic doctrine. He continued to officiate mass from time to time until later in life. In 1755 he was appointed to teach humanities at the College of Reggio Emilia and then went on to be professor of philosophy at Modena in the University and College of Nobles. He indicated, however, in a letter to Charles Bonnet, that his teaching responsibilities robbed him of his time, which he preferred to dedicate to scientific pursuits.

Spallanzani read voraciously but was a persistent skeptic, hesitant to believe anything that he could not prove himself. Unconvinced by Needham and Buffon’s description of the genesis of animalcules in plant and animal infusions, Spallanzani carefully replicated their study and showed their techniques were inadequate and therefore that their conclusions about the existence of spontaneous generation were unwarranted. He published his results refuting spontaneous generation in 1765 and thereby initiated a lifelong correspondence with Bonnet. An avid and staunch preformationist, Bonnet seized upon Spallanzani’s results to support his theoretical inclinations and challenged him to carry on his own work investigating regeneration in flatworms. Spallanzani rose to the challenge and returned Bonnet’s letter with an explanation of his many sectioning experiments on a wide variety of animals.

Spallanzani performed hundreds of salamander tail amputations, believing exhaustive repetition was necessary to confirm results. Interested in the origin of regenerating tissue, he closely examined the interface between the stump and the regenerated tail. Observation alone offered no conclusions. He had trouble believing that an organized tail could result from a simple outgrowth, but continued to look for evidence in regenerating tadpole and salamander tails that could support his inclination toward the existence of preformed germs. He openly reported his observations, even those that questioned preformationism, once suggesting that tail regenerates in tadpoles appeared to be the result of an elongation, a comment which surely must have disturbed Bonnet but nevertheless failed to persuade him to consider epigenesis seriously.

Interested in questions about generation, Spallanzani performed the first artificial insemination of a viviparous animal, a spaniel dog, a feat he recognized as one of his greatest accomplishments. These results further convinced him of the ovist preformationist doctrine. He interpreted his many findings as evidence against epigenesis and the role of sperm, which he identified as “animalcules,” in generation.

In 1776 Spallanzani accepted a professorship at the University of Pavia where he remained for the next thirty years and published extensively. He was a member of the ten most distinguished Italian academies and a foreign associate to another dozen scientific societies across Europe. His work has been celebrated for its creative approach and rigorous use of scientific methodologies inspiring many scientists, including Thomas Hunt Morgan, to revisit his studies.

• Dinsmore, Charles E., ed. “Lazzaro Spallanzani: Concepts of Generation and Regeneration.” in A History of Regeneration Research: Milestones in the Evolution of a Science , 67–89. Cambridge: Cambridge University Press, 1991.
• Dolman, Claude E. “Spallanzani, Lazzaro.” Dictionary of Scientific Biography Volume 12: 553–67.

How to cite

Articles rights and graphics.

Copyright Arizona Board of Regents Licensed as Creative Commons Attribution-NonCommercial-Share Alike 3.0 Unported (CC BY-NC-SA 3.0)  

Last modified

Share this page.

Want to create or adapt books like this? Learn more about how Pressbooks supports open publishing practices.

3. The Cell

3.1 Spontaneous Generation

Learning objectives.

• Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms
• Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation

CLINICAL FOCUS: Part 1

Barbara is a 19-year-old college student living in the dormitory. In January, she came down with a sore throat, headache, mild fever, chills, and a violent but unproductive (i.e., no mucus) cough. To treat these symptoms, Barbara began taking an over-the-counter cold medication, which did not seem to work. In fact, over the next few days, while some of Barbara’s symptoms began to resolve, her cough and fever persisted, and she felt very tired and weak.

• What types of respiratory disease may be responsible?

Jump to the next Clinical Focus box

Humans have been asking for millennia: Where does new life come from? Religion, philosophy, and science have all wrestled with this question. One of the oldest explanations was the theory of spontaneous generation, which can be traced back to the ancient Greeks and was widely accepted through the Middle Ages.

The Theory of Spontaneous Generation

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation, the notion that life can arise from nonliving matter. Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. [1]

This theory persisted into the 17th century, when scientists undertook additional experimentation to support or disprove it. By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain moulded, mice appeared. Jan Baptista van Helmont , a 17th century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse populations to flourish.

However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), performed an experiment in 1668 that was one of the first to refute the idea that maggots (the larvae of flies) spontaneously generate on meat left out in the open air. He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Redi left meat in each of six containers ( Figure 3.2 ). Two were open to the air, two were covered with gauze, and two were tightly sealed. His hypothesis was supported when maggots developed in the uncovered jars, but no maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies, not the product of spontaneous generation.

In 1745, John Needham (1713–1781) published a report of his own experiments, in which he briefly boiled broth infused with plant or animal matter, hoping to kill all preexisting microbes. [2] He then sealed the flasks. After a few days, Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures. He argued that the new microbes must have arisen spontaneously. In reality, however, he likely did not boil the broth enough to kill all preexisting microbes.

Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth. [3] As in Needham’s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani’s results contradicted the findings of Needham: Heated but sealed flasks remained clear, without any signs of spontaneous growth, unless the flasks were subsequently opened to the air. This suggested that microbes were introduced into these flasks from the air. In response to Spallanzani’s findings, Needham argued that life originates from a “life force” that was destroyed during Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation ( Figure 2 ).

• Describe the theory of spontaneous generation and some of the arguments used to support it.
• Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.

Disproving Spontaneous Generation

The debate over spontaneous generation continued well into the 19th century, with scientists serving as proponents of both sides. To settle the debate, the Paris Academy of Sciences offered a prize for resolution of the problem. Louis Pasteur , a prominent French chemist who had been studying microbial fermentation and the causes of wine spoilage, accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a “life force” to the broth but rather airborne microorganisms.

Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks), in which he boiled broth to sterilize it ( Figure 3.4 ). His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. However, should the necks be broken, microorganisms would be introduced, contaminating the flasks and allowing microbial growth within the broth.

Pasteur’s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “ Omne vivum ex vivo ” (“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that “…life is a germ and a germ is life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” [4] To Pasteur’s credit, it never has.

• How did Pasteur’s experimental design allow air, but not microbes, to enter, and why was this important?
• What was the control group in Pasteur’s experiment and what did it show?

Key Takeaways

• The theory of spontaneous generation states that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks.
• Experimentation by Francesco Redi in the 17th century presented the first significant evidence refuting spontaneous generation by showing that flies must have access to meat for maggots to develop on the meat. Prominent scientists designed experiments and argued both in support of (John Needham) and against (Lazzaro Spallanzani) spontaneous generation.
• Louis Pasteur is credited with conclusively disproving the theory of spontaneous generation with his famous swan-neck flask experiment. He subsequently proposed that “life only comes from life.”

Multiple Choice

Fill in the blank, short answer.

• Explain in your own words Pasteur’s swan-neck flask experiment.
• Explain why the experiments of Needham and Spallanzani yielded in different results even though they used similar methodologies.

Critical Thinking

• What would the results of Pasteur’s swan-neck flask experiment have looked like if they supported the theory of spontaneous generation?

Media Attributions

• OSC_Microbio_03_01_Rediexpt
• https://link.springer.com/content/pdf/10.1007%2Fs10739-017-9494-7.pdf ↵
• E. Capanna. “Lazzaro Spallanzani: At the Roots of Modern Biology.” Journal of Experimental Zoology 285 no. 3 (1999):178–196. ↵
• R. Mancini, M. Nigro, G. Ippolito. “Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.” Le Infezioni in Medicina 15 no. 3 (2007):199–206. ↵
• R. Vallery-Radot. The Life of Pasteur , trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142. ↵

Microbiology: Canadian Edition Copyright © 2019 by Wendy Keenleyside is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

Share This Book

• The Theory of Biogenesis

What is Biogenesis?

An important theory in biology and molecular genetics, Biogenesis postulates the production of new living organisms from pre-existing life. Read ahead as we explore this seminal theory that changed age-old beliefs.

Biogenesis is based on the theory that life can only come from life, and it refers to any process by which a lifeform can give rise to other lifeforms. For instance, a chicken laying eggs, which hatch and become baby chicken.

Meaning of Biogenesis

The term ‘biogenesis’ comes from ‘bio’ meaning ‘life’, and ‘ genesis’, meaning ‘beginning’. Rudolf Virchow, in 1858, had come up with the hypothesis of biogenesis, but could not experimentally prove it. In 1859, Louis Pasteur set up his demonstrative experiments to prove biogenesis right down to a bacterial level. By 1861, he succeeded in establishing biogenesis as a solid theory rather than a controversial hypothesis.

What Was the Idea of Spontaneous Generation?

The belief in a spontaneous generation is age-old, quite literally. Aristotle in Ancient Greece first pronounces the idea. And consequently, the idea also came to be known as Aristotelian Abiogenesis.

The reason behind the resounding faith in this idea was perhaps the elusive and stealthy nature of the creatures attributed to it, i.e, mice, bacteria, flies, maggots, etc.

The 18th-century path-breaking invention of the microscope that allows most of these creatures, so we can observe them under the microscope and de-mystify their origin. By the time Pasteur set about to do his work in the field, macroscopic biogenesis was already accepted by the scientific community at large. He only had to confirm microscopic biogenesis to prove the hypothesis beyond doubt.

Macroscopic Biogenesis: Francesco Redi’s Experiment

Francesco Redi, as far back as 1668, had set out to refute the idea of macroscopic spontaneous generation, by publishing the results of his experimentation on the matter. Instead of his experiment , Redi had placed some rotting meat in two containers, one with a piece of gauze covering the opening, and the other without it.

He noticed that in the container without the gauze, maggots would grow on the meat itself. However, when he provided the gauze, the maggots would appear on the gauze instead of on the meat. He also observed that flies tend to lay eggs as close to a food source as possible. Thus, he surmised the possibility of macroscopic biogenesis.

Microscopic Biogenesis

Spallanzani’s experiment.

Source: Emaze

He solved this problem by drawing out all the air in the container after sealing it. After experimenting with this manner, he achieved his desired results of a broth that had not clouded with bacterial growth, in line with the theory of biogenesis.

However, his inference was countered by critics who asserted that air was indispensable to support life, therefore the lack of bacterial growth should be attributed to the lack of air, rather than the fact that bacteria spread through contamination. For almost a century since this criticism lay unchallenged.

Pasteur’s Experiment   

The caveat of Pasteur’s 1859 experiment was to establish that microbes live suspended in air, and can contaminate food and water, however, the microbes do not simply appear out of thin air. As the primary step to his experiment, Pasteur boiled beef broth in a special flask that had its long neck bent downwards and then upwards.

This interesting contraption ensured the free diffusion of air, and at the same time prevent any bacterial contamination. As long as the apparatus remained upright, the flask remained free of any bacterial growth.

Once we slant the flask, it allows the broth to pass beyond the ‘goose-neck’ bend of the flask’s neck. The broth became clouded with bacterial growth in no time. This path-breaking experiment not only silenced all the criticism based on Spallanzani’s experiment but also cemented the Law of Biogenesis.

Law of Biogenesis Vs. Evolutionary Theory

Scientist fears that the law of biogenesis opposes the theory of evolution. It has surmised that all life stems from inorganic matter from billions of years ago. However, biogenesis simply refutes the theory of spontaneous generation and delves in a matter of generational time-span, and not of what may be achieved over thousands of generations.

While the evolutionary theories take into account the lack of predators, the difference in the chemical composition of the Earth’s atmosphere during the inception of life on Earth, as well as the trial-and-error that had taken place over millions of years to bring us to the stage of life on this planet we witness now, these do not concern the law of biogenesis at all.

Whereas the evolutionary theory demonstrates how life on earth took millions of years of trial-and-error and conducive but very different atmospheric conditions, the theory of spontaneous generation had asserted that complex life could simply appear fully formed in a matter of days. This is the belief that biogenesis had successfully challenged.

Solved Question for You

Q. Who Has Propounded the Theory of Spontaneous Generation?

• Spallanzani

Ans. C. Aristotle. The idea was first propounded by Aristotle in Ancient Greece. Consequently, the idea came to be known as Aristotelian Abiogenesis.

Customize your course in 30 seconds

Which class are you in.

Molecular Genetics

• What are Genotypes and Phenotypes? – Definition and Examples
• Chromatid – Definition, Parts, and Functions
• Chromosome – Definition, Structure, Function, Examples
• Homozygous – Definition, Characteristics, and Examples
• Chargaff’s Rule – What is Chargaff’s Rule of Base Pairing?
• Genetic Diversity – Definition, Importance, Examples
• Heterozygous – Definition and Characteristics
• Difference Between Homozygous & Heterozygous

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Download the App

Scientists Once Dressed Frogs in Tiny Pants to Study Reproduction

In the 18th century, fertility research got particularly creative..

You might value pants for their leg-sheathing, buttock-concealing and pocket-generating powers—but they can also serve as frog genital shackles, and they played a crucial role in 18th-century fertility research.

Reproduction wasn’t always a settled science. Prior to cell theory and the invention of the microscope, inquisitive minds engaged in quite a bit of guesswork over where babies come from. As early as 350 B.C., Aristotle proposed a theory of epigenesis—which was essentially correct. But not everyone cared for the idea of a sperm-and-egg collaboration.

So-called preformationists believed organisms developed from miniature versions of themselves. For instance, in the 17th and 18th centuries, Dutch physicist Nicolaas Hartsoeker took a hardline “spermist” approach, postulating that each sperm contained a complete preformed humanoid, or homunculus . Ovists, on the other hand, believed the egg contained all that was needed and merely required male seed as a chemical trigger. Still others pointed to maggots or fermentation as proof of spontaneous generation, at least in simpler organisms.

To reach our current understanding of reproduction, these fanciful theories would need to fall by science’s sword—and fall they did. Physician Francesco Redi’s classic 1668 experiment, in which he separated meat from swarming flies with gauze, struck a crucial blow to spontaneous generation. The ovists and the spermists would prove more difficult to defeat, which brings us to Italian physiologist and priest Lazzaro Spallanzani (1729-1799)—and his tiny frog pants.

Spallanzani was a devoted ovist. As evolutionary geneticist Kenneth Weiss points out in his 2004 paper The Frog in Taffeta Pants , Spallanzani and other microscope-users of the day knew semen contained “wormified beings in a thicker component, and a thinner liquid.” Based on popular theories concerning inheritable intestinal worms, Spallanzani thought the sperm might be mere parasites and that the seminal fluid alone served as a chemical trigger for the all-encompassing egg.

In the 1760s, to better understand the process, Spallanzani repeated a 1736 experiment by French scientist René Antoine Ferchault de Réaumur. In the original experiment, Réaumur enshrouded the posteriors of male frogs in pants made from pig’s bladder and taffeta. He aimed to prevent the dousing of frog eggs and examine any male frog secretions caught in the pants to gain a better understanding of how fertilization works. The frogs’ tendency to wriggle out of the pants made these experiments challenging.

In his follow-up experiment decades later, Spallanzani described the prophylactic garment as “pants,” but without illustration or artifact, we’re left to imagine the most ridiculous possibilities. (Tiny lederhosen, perhaps?). Spallanzani’s pants prevented the thicker portion of the semen from reaching the egg, though he was still loathe to credit its wormlike contents with fertilization.

According to Ernesto Capanna’s Lazzaro Spallanzani: At the Roots of Modern Biology , Spallanzani went on to throw pants on various amphibian species. In each case, he collected semen from the taffeta pants and successfully carried out artificial insemination on a female of the same species. In time, he even upgraded to dogs, but didn’t need special pants for canine semen collection.

Spallanzani remained an ovist his entire life, always finding a way to credit the egg alone as the human “tadpole.” He died of bladder cancer in 1799 and the bladder itself remains preserved in Pavia, Italy .

The scientific understanding of reproduction has changed a great deal over the last two centuries, but animal breeding programs continue. The methods of semen collection remain, if we’re being honest, a bit awkward. Plus, every now and then, a well-meaning scientist busts out a pair of experimental pants. In 1993, Egyptian sexologist Dr. Ahmed Shafik dressed rats in polyester pants to study the fabric’s effects on sexual activity.

Never doubt the research potential of tiny trousers.

For Centuries, People Celebrated a Little Boy’s First Pair of Trousers

Using an ad blocker?

We depend on ad revenue to craft and curate stories about the world’s hidden wonders. Consider supporting our work by becoming a member for as little as $5 a month.

The Giant Frog Farms of the 1930s Were a Giant Failure

See the World’s Most Ordinary Animals as You Never Have Before

Oxford Bags, the Ridiculously Wide-Legged Trousers of the 1920s

How the Skort Went From Rebellious Garment to Athleisure Staple

Follow us on Twitter to get the latest on the world's hidden wonders.

Like us on Facebook to get the latest on the world's hidden wonders.

Pre-Order Atlas Obscura: Wild Life Today!

Add some wonder to your inbox, we'd like you to like us.

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings
• My Bibliography
• Collections
• Citation manager

Save citation to file

Email citation, add to collections.

• Create a new collection
• Add to an existing collection

Add to My Bibliography

Your saved search, create a file for external citation management software, your rss feed.

• Search in PubMed
• Search in NLM Catalog
• Add to Search

[Experiments of Lazzaro Spallanzani on digestion with therapeutic applications of gastric juice]

• PMID: 4131390

PubMed Disclaimer

Similar articles

• [Historical data of gastric physiology. Its current status and physiological aspects of the operated stomach]. Pera Madrazo C, Pera Jiménez C. Pera Madrazo C, et al. Rev Esp Enferm Apar Dig. 1973 Oct 1;41(3):331-50. Rev Esp Enferm Apar Dig. 1973. PMID: 4585495 Spanish. No abstract available.
• The discovery of gastric acid. Baron JH. Baron JH. Gastroenterology. 1979 May;76(5 Pt 1):1056-64. Gastroenterology. 1979. PMID: 374174 No abstract available.
• William Beaumont experiments begun 147 years ago this month. Bittker A. Bittker A. Mich Med. 1969 Jun;68(11):583-9. Mich Med. 1969. PMID: 4892649 No abstract available.
• [Pancreas in the digestive organ system]. Klimov PK. Klimov PK. Klin Med (Mosk). 1980 Feb;58(2):11-8. Klin Med (Mosk). 1980. PMID: 6988640 Review. Russian. No abstract available.
• The development of digestive function in the pig. Manners MJ. Manners MJ. Proc Nutr Soc. 1976 May;35(1):49-55. Proc Nutr Soc. 1976. PMID: 7786 Review. No abstract available.
• Gastric Cancer in History: A Perspective Interdisciplinary Study. Topi S, Santacroce L, Bottalico L, Ballini A, Inchingolo AD, Dipalma G, Charitos IA, Inchingolo F. Topi S, et al. Cancers (Basel). 2020 Jan 22;12(2):264. doi: 10.3390/cancers12020264. Cancers (Basel). 2020. PMID: 31978985 Free PMC article.

Publication types

• Search in MeSH

Personal name as subject

• Citation Manager

NCBI Literature Resources

MeSH PMC Bookshelf Disclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

Digestion, reproduction : les expériences folles de Spallanzani

Pour être un bon scientifique, il faut avoir un petit grain de folie. On a tous en tête la fameuse photo d’Albert Einstein tirant la langue. Certains scientifiques, moins connus qu’Einstein par le grand public, ont réalisé des expériences un peu folles. C’est le cas notamment de Lazzaro Spallanzani, abbé scientifique italien du 18ème siècle, qui étudia rien de moins que la biologie, la zoologie, la géologie, la vulcanologie…autant dire presque rien !

Cet article peut intéresser des élèves de 5ème et 4ème – Programme SVT

Spallanzani est connu de tous les collégiens pour avoir effectué de nombreuses recherches dans le domaine de la digestion. La première expérience un peu folle que je voulais vous présenter concerne en effet ce domaine. Voici ce qu’il écrivit dans son livre intitulé «  Expériences sur la digestion de l’homme et de différentes espèces d’animaux  » publié en 1777 :

«  Ne semblerait-il pas que l’action des suc gastriques humains sur les aliments est aidée par la compression de l’estomac? Pour décider cette question, il fallait mettre les aliments dans de petits tubes, parce que si la digestion ne se faisait pas, ou se faisait mal, c’était une preuve qu’il manquait quelque chose d’utile, et alors il était assez probable que ce serait la force triturante. J’étais donc physiquement obligé d’avaler des tubes ; et comme j’avais vu dans mes précédentes expériences, qu’il ne m’arrivait aucun mal en avalant les petites bourses, je dirais franchement que j’avalais sans crainte les tubes, que je fis faire en bois et non en laiton, craignant quelques accidents fâcheux par leur séjour dans l’estomac ou dans les boyaux (…) . Les sucs gastriques ne les avaient pas rongés, les tubes s’étaient seulement noircis par un long séjour dans l’estomac. Le calibre des petits tubes que j’employais était de trois lignes, leur longueur avait cinq lignes, les parois étaient couvertes de trous, afin que le suc gastrique de mon estomac pût les pénétrer de toutes parts ; je les couvris seulement avec une toile, pour en fermer l’entrée, pendant leur longue traversée des intestins. Je n’avalais d’abord qu’un seul petit tube, où j’avais mis trente-six grains de chair de veau cuite et mâchée : il sortit heureusement au bout de vingt-deux heures, mais il ne contenait plus de chair, ni rien du tout, parce qu’il avait été fort bien fermé par les toiles . »

Notez deux choses de ce petit texte : le dévouement de Spallanzani à la science, qui se sentait «  physiquement obligé d’avaler des tubes  » et son soulagement («  heureusement « ) lorsque le tube en bois ressorti par les voies naturelles. L’abbé italien venait de montrer par cette expérience que la digestion ne se faisait pas grâce à un mécanisme de broyage mais plutôt grâce à une action chimique : le liquide présent dans l’estomac permet de dissoudre à lui seul les aliments.

La seconde expérience farfelue de Spallanzani, dont je voulais vous parler, concerne la reproduction des grenouilles. A l’époque on ne savait pas vraiment comment « se faisaient les bébés » (cela fera peut-être l’objet d’un futur article sur Kidi !). Spallanzani pensait d’ailleurs que le nouvel individu existait déjà dans les ovules de la mère et que finalement le père n’avait aucun rôle dans la reproduction. Afin de confirmer ou non cette hypothèse, l’abbé italien décida de mettre un petit slip en cuir à une grenouille mâle. Après l’accouplement, la grenouille femelle libéra ses œufs mais aucun têtard ne naquit. Spallanzani s’interrogea. Son hypothèse était donc fausse ! Peut-être que le mâle joue un rôle important dans la fécondation ?

En récupérant les petits slips sur les grenouilles mâles, il remarqua la présence d’une substance transparente. Il récupéra cette substance et la mit au contact des œufs pondus par la grenouille femelle. Quelques jours plus tard, il constata la naissance des petits têtards. Il venait de réaliser la première fécondation in vitro de l’histoire en mettant directement en contact des spermatozoïdes et des ovules ! Tout ça grâce à des petits slips en cuir !

Dans le livre « Expériences pour servir à l’histoire de la génération des animaux et des plantes » publié en 1785, Jean Senebier évoqua Spallanzani dans ces termes : «  L’abbé Spallanzani (a su) lutter victorieusement avec la Nature, et produire, par son adresse, les mêmes effets qu’elle a opéré si souvent depuis la création, et dont elle avait su voiler jusqu’aujourd’hui les moyens.  » Bel hommage n’est-ce pas ?

Laisser un commentaire Annuler la réponse

Votre adresse e-mail ne sera pas publiée. Les champs obligatoires sont indiqués avec *

Commentaire

Prévenez-moi de tous les nouveaux commentaires par e-mail.

Prévenez-moi de tous les nouveaux articles par e-mail.

Ce site utilise Akismet pour réduire les indésirables. En savoir plus sur comment les données de vos commentaires sont utilisées .

© Kidi'science

• Advertise with Us
• Privacy Policy

Pasteur Brewing Louis Pasteur – Science, Health, and Brewing

Spallanzani and louis pasteur – spontaneous generation.

Louis Pasteur’s experiments fueled his scientific work and validating his ideas with careful experimention was his passion. The most famous Louis Pasteur experiment was that which he created to disprove the theory of Sponteneous Generation, the theory that living organisms can be “spontaneously generated” from non-living material. Through his experimentation Louis Pasteur concluded that microscopic organisms are present in the atmosphere. Therefore, any substance or material exposed to the air would be potentially subject to living processes. He created a special “swan neck flask” for this ground breaking experiment.

To allow you to participate in some historically important issues in science, to conduct experiments, and to reason from the data while experiencing the limitations of the data in reaching valid conclusions.

• Wear safety goggles.
• Use caution when handling hot liquids.

Seven 250 ml Erlenmeyer flasks will be set up according to the following conditions:

Flask 1 (Overall Control)

• Add 70 ml of clear broth to this flask. Do not cover.

Flask 2 (Spallanzani’s Control)

• 70 ml of clear broth to which has been added 10 ml of water.
• Boil gently for 15 minutes (about 10 ml of water should evaporate). Check the liquid level with the control flask and adjust, if necessary.
• LEAVE OPEN.

Flask 3 (Spallanzani’s Experiment)

• Add 10 ml of water to the 70 ml of clear broth.
• Boil gently for 15 minutes with a solid rubber stopper resting at an angle in the mouth of the flask (a loose plug).
• At the end of the boiling period, plug the flask with the rubber stopper.
• Seal with melted wax or paraffin.

Flask 4 (Pasteur’s Control)

• Heat the 70 ml of clear broth in a pressure cooker or autoclave for 15 minutes at 15 psi. LEAVE OPEN.

Flask 5 (Modified Pasteur’s Control)

• Flask with 70 ml of clear broth is plugged with a one-hole stopper into which has been inserted a straight glass tube (8-10 cm long, 7-8 mm diameter).
• Repeat the autoclaving procedure as listed for Flask #4.
• After autoclaving, seal the stopper to the neck of the flask as well as around the glass tube exiting the stopper, using melted wax or paraffin.

Flask 6 (Pasteur’s First Experiment)

• Add 70 ml of clear broth to the flask.
• Plug the flask with a one-hole stopper into which is inserted a J-shaped glass tube.
• Autoclave as done with Flasks #4 and #5.
• Seal stopper and glass tube as in Flask #5.

Flask 7 (Pasteur’s Final Experiment)

• Flask with 70 ml of clear broth is plugged with a one-hole stopper and an S-shaped glass tube.
• Autoclave the apparatus as in Flasks #4-#6. Seal as in Flask #5.
• Place all flasks in an area with reasonably constant temperature and away from sunlight and excessive heat.

Post-Laboratory Activity

• Look for changes in the flasks each day for 1 week (cloudiness is a sign of the presence of microorganisms; other changes include appearance of “scum” and mold). Record the day/date for each change.
• Continue observations weekly for 5 weeks.
• For flasks that have changed over 5 weeks, open the flasks and note any odors.
• For flasks that show no change, continue to observe indefinitely.

Data Analysis

• What happened in Flasks #2 and #3 (Spallanzani’s eperiment)? Were there any differences between the two flasks over the 5-week period?
• In Spallanzani’s experimentation, he found that no turbidity or foul odor developed in sealed Flask #3. His critics claimed that this did not refute the concept of spontaneous generation; it did not show that microbes had to get into the broth from the outside. How would these critics have to argue to defend their point of view in light of the evidence?
• For the work of Pasteur in Flasks #4-#7, what is the function of Flask #4?
• Why did Pasteur provide openings in his flasks? How does this relate to supporters of the idea of spontaneous generation and critics of Spallanzani?
• How do you explain the results obtained in Flask #7? Does this refute the concept of spontaneous generation? (See the introductory historical reading for this laboratory exercise.)
• Compare the results found in Flask #1 with those of Flasks #2 and #4. Are the results in agreement with what you would predict as a spontaneous generation believer? As a Pasteurian? Would the issue of spontaneous generation be resolved with these three setups?

Related Articles

Pasteur Swan Neck Flask Experiment

Louis Pasteur, Francesco Redi, and Spontaneous Generation for Kids

Francesco Redi and Spontaneous Generation

Summary Report of the Experiments Conducted at Pouilly-le-Fort, Near Melun, on the Anthrax Vaccination

 by Louis Pasteur (with the Collaboration of Mr. Chamberland and Mr. Roux) Originially published in …

Leave a Reply

You must be logged in to post a comment.