- Anatomy & Physiology
- Astrophysics
- Earth Science
- Environmental Science
- Organic Chemistry
- Precalculus
- Trigonometry
- English Grammar
- U.S. History
- World History
... and beyond
- Socratic Meta
- Featured Answers
What conclusion did Francesco Redi draw after performing his experiment with flies and meat?
Redi experiment (1665)
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.
As an Amazon Associate we earn from qualifying purchases.
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
© Jan 10, 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.
Origin of Life: Spontaneous Generation
- Spontaneous Generation
Origin of Life
- Introduction
- Early Earth Environment
It was once believed that life could come from nonliving things, such as mice from corn, flies from bovine manure, maggots from rotting meat, and fish from the mud of previously dry lakes. Spontaneous generation is the incorrect hypothesis that nonliving things are capable of producing life. Several experiments have been conducted to disprove spontaneous generation; a few of them are covered in the sections that follow.
Redi's Experiment and Needham's Rebuttal
In 1668, Francesco Redi, an Italian scientist, designed a scientific experiment to test the spontaneous creation of maggots by placing fresh meat in each of two different jars. One jar was left open; the other was covered with a cloth. Days later, the open jar contained maggots, whereas the covered jar contained no maggots. He did note that maggots were found on the exterior surface of the cloth that covered the jar. Redi successfully demonstrated that the maggots came from fly eggs and thereby helped to disprove spontaneous generation. Or so he thought.
In England, John Needham challenged Redi's findings by conducting an experiment in which he placed a broth, or gravy, into a bottle, heated the bottle to kill anything inside, then sealed it. Days later, he reported the presence of life in the broth and announced that life had been created from nonlife. In actuality, he did not heat it long enough to kill all the microbes.
Spallanzani's Experiment
Lazzaro Spallanzani, also an Italian scientist, reviewed both Redi's and Needham's data and experimental design and concluded that perhaps Needham's heating of the bottle did not kill everything inside. He constructed his own experiment by placing broth in each of two separate bottles, boiling the broth in both bottles, then sealing one bottle and leaving the other open. Days later, the unsealed bottle was teeming with small living things that he could observe more clearly with the newly invented microscope. The sealed bottle showed no signs of life. This certainly excluded spontaneous generation as a viable theory. Except it was noted by scientists of the day that Spallanzani had deprived the closed bottle of air, and it was thought that air was necessary for spontaneous generation. So although his experiment was successful, a strong rebuttal blunted his claims.
Pasteurization originally was the process of heating foodstuffs to kill harmful microorganisms before human consumption; now ultraviolet light, steam, pressure, and other methods are available to purify foodsin the name of Pasteur.
Pasteur's Experiment
Louis Pasteur, the notable French scientist, accepted the challenge to re-create the experiment and leave the system open to air. He subsequently designed several bottles with S-curved necks that were oriented downward so gravity would prevent access by airborne foreign materials. He placed a nutrient-enriched broth in one of the goose-neck bottles, boiled the broth inside the bottle, and observed no life in the jar for one year. He then broke off the top of the bottle, exposing it more directly to the air, and noted life-forms in the broth within days. He noted that as long as dust and other airborne particles were trapped in the S-shaped neck of the bottle, no life was created until this obstacle was removed. He reasoned that the contamination came from life-forms in the air. Pasteur finally convinced the learned world that even if exposed to air, life did not arise from nonlife.
Excerpted from The Complete Idiot's Guide to Biology © 2004 by Glen E. Moulton, Ed.D.. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books , a member of Penguin Group (USA) Inc.
To order this book direct from the publisher, visit the Penguin USA website or call 1-800-253-6476. You can also purchase this book at Amazon.com and Barnes & Noble .
- Origin of Prokaryotes and Eukaryotes: Origin of Prokaryotes
Here are the facts and trivia that people are buzzing about.
- 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
- When did science begin?
- Where was science invented?
Francesco Redi
Our editors will review what you’ve submitted and determine whether to revise the article.
- Court Scientists - Biography of Francesco Redi
- Institute and Museum of the History of Sciences - Biography of Francesco Redi
- Francesco Redi - Student Encyclopedia (Ages 11 and up)
Francesco Redi (born Feb. 18, 1626, Arezzo , Italy—died March 1, 1697, Pisa) was an Italian physician and poet who demonstrated that the presence of maggots in putrefying meat does not result from spontaneous generation but from eggs laid on the meat by flies.
He read in the book on generation by William Harvey a speculation that vermin such as insects, worms, and frogs do not arise spontaneously, as was then commonly believed, but from seeds or eggs too small to be seen. In 1668, in one of the first examples of a biological experiment with proper controls, Redi set up a series of flasks containing different meats, half of the flasks sealed, half open. He then repeated the experiment but, instead of sealing the flasks, covered half of them with gauze so that air could enter. Although the meat in all of the flasks putrefied, he found that only in the open and uncovered flasks, which flies had entered freely, did the meat contain maggots. Though correctly concluding that the maggots came from eggs laid on the meat by flies, Redi, surprisingly, still believed that the process of spontaneous generation applied in such cases as gall flies and intestinal worms. Redi is known as a poet chiefly for his Bacco in Toscana (1685; “Bacchus in Tuscany”).
Francesco Redi: Founder of Experimental Biology
- Chemical Laws
- Periodic Table
- Projects & Experiments
- Scientific Method
- Biochemistry
- Physical Chemistry
- Medical Chemistry
- Chemistry In Everyday Life
- Famous Chemists
- Activities for Kids
- Abbreviations & Acronyms
- Weather & Climate
- Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
- B.A., Physics and Mathematics, Hastings College
Francesco Redi was an Italian naturalist, physician, and poet. Besides Galileo, he was one of the most important scientists who challenged Aristotle 's traditional study of science. Redi gained fame for his controlled experiments. One set of experiments refuted the popular notion of spontaneous generation—a belief that living organisms could arise from nonliving matter. Redi has been called the "father of modern parasitology" and the "founder of experimental biology".
Birth : February 18, 1626, in Arezzo, Italy
Death : March 1, 1697, in Pisa Italy, buried in Arezzo
Nationality : Italian (Tuscan)
Education : University of Pisa in Italy
Published Work s: Francesco Redi on Vipers ( Osservazioni intorno alle vipere) , Experiments on the Generation of Insects ( Esperienze Intorno alla Generazione degli Insetti) , Bacchus in Tuscany ( Bacco in Toscana )
Major Scientific Contributions
Redi studied venomous snakes to dispel popular myths about them. He demonstrated that it is not true that vipers drink wine, that swallowing snake venom is toxic, or that venom is made in a snake's gallbladder. He found that venom was not poisonous unless it entered the bloodstream and that the progression of venom in the patient could be slowed if a ligature was applied. His work paved the foundation for the science of toxicology .
Flies and Spontaneous Generation
One of Redi's most famous experiments investigated spontaneous generation . At the time, scientists believed in the Aristotelian idea of abiogenesis , in which living organisms arose from non-living matter. People believed rotting meat spontaneously produced maggots over time. However, Redi read a book by William Harvey on generation in which Harvey speculated that insects, worms, and frogs might arise from eggs or seeds too tiny to be seen. Redi devised and performed the now-famous experiment in which six jars, half left in open air and half covered with fine gauze that permitted air circulation but kept out flies, were filled with either an unknown object, a dead fish, or raw veal. The fish and veal rotted in both groups, but maggots only formed in the jars open to air. No maggots developed in the jar with the unknown object.
He performed other experiments with maggots, including one where he placed dead flies or maggots in sealed jars with meat and observed living maggots did not appear. However, when he placed living flies were placed in a jar with meat, maggots did appear. Redi concluded maggots came from living flies, not from rotting meat or from dead flies or maggots.
The experiments with maggots and flies were important not only because they refuted spontaneous generation, but also because they used control groups , applying the scientific method to test a hypothesis.
Parasitology
Redi described and drew illustrations of over one hundred parasites, including ticks, nasal flies, and the sheep liver fluke. He drew a distinction between the earthworm and the roundworm , which were both considered to be helminths prior to his study. Francesco Redi performed chemotherapy experiments in parasitology, which were noteworthy because he used an experimental control. In 1837, Italian zoologist Filippo de Filippi named the larval stage of the parasitic fluke "redia" in honor of Redi.
Redi's poem "Bacchus in Tuscany" was published after his death. It is considered among the best literary works of the 17th century. Redi taught the Tuscan language, supported the writing of a Tuscan dictionary, was a member of literary societies, and published other works.
Redi was a contemporary of Galileo, who faced opposition from the Church. Although Redi's experiments ran contrary to the beliefs of the time, he did not have the same sort of problems. This may well have been because of the different personalities of the two scientists. While both were outspoken, Redi did not contradict the Church. For example, in reference to his work on spontaneous generation, Redi concluded omne vivum ex vivo ("All life comes from life").
It's interesting to note that despite his experiments, Redi believed spontaneous generation could occur, for instance, with intestinal worms and gall flies.
Altieri Biagi; Maria Luisa (1968). Lingua e cultura di Francesco Redi, medico . Florence: L. S. Olschki.
- Understanding Experimental Groups
- 10 Things You Need To Know About Chemistry
- Steps of Transcription From DNA to RNA
- The Difference Between Control Group and Experimental Group
- How to Calculate Experimental Error in Chemistry
- Hypothesis Definition (Science)
- Baggie Chemistry Experiments
- Examples of Diffusion in Chemistry
- What Is an Experimental Constant?
- What Is a Control Group?
- How to Calculate Percent Error
- Scientific Method Vocabulary Terms
- What Is a Testable Hypothesis?
- What Is the Difference Between a Control Variable and Control Group?
- What Is an Experiment? Definition and Design
- Understanding Simple vs Controlled Experiments
What is Redi's conclusion in experiment?
John Needham is credited for tests that gave bearing to the belief of spontaneous generation, or the sudden creation of life. His tests involved boiling broth mixtures to remove any existing bacteria, then cooling them and sealing them. This ended up being debunked, as the broth mixtures not only weren't boiled long enough to actually kill the bacteria, but also were cooled in open air, which would have allowed bacteria in.
What_did_john_needham_conclude_from_his_test_of_redi%27s_findings
Nothing i think hope this helps!!
kissed her in the bathroom
Add your answer:
What is the control group in Redis Experiment?
the control was the open jar with meat
How did francisco redis experiment change science now?
people believed on spontaneous generation and now they don't after his discovery!
What are the results from an experiment called?
The results of an experiment are called your data.
When a scientist does an experiment and draws a conclusion how does the conclusion differ from a theory?
A conclusion is what the experimenter observes from the experiment andwhether your hypothesis was proven correct or not.While the theory is the facts that is known about the experiment
What are the final two steps in an experiment experiment?
1. Conclusion 2. Data analysis
Top Categories
In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation.
Francesco Redi (1626-1698)
Francesco Redi, son of Florentine physician Cecilia de’ Ghinci and Gregorio Redi, was born in Arezzo, Italy, on 18 February 1626. He studied philosophy and medicine at the University of Pisa, graduating on 1 May 1647. A year later, Redi moved to Florence and registered at the Collegio Medico. There he served at the Medici Court as both the head physician and superintendent of the ducal pharmacy and foundry. Redi was also a member of the Accademia del Cimento, which flourished from 1657–1667. It was during this decade that Redi produced his most important works.
In 1664 Redi wrote his Osservazioni intorno alle vipere to his friend Lorenzo Magalotti, secretary of the Accademia. In this work Redi states that snake venom is unrelated to the snake’s bile, an idea contrary to popular belief. Redi performed countless experiments on the effects of snakebites, discovering that venom was only effective when introduced into the bloodstream via a bite. In order to prevent the passage of venom into the heart, Redi applied concepts relating to blood circulation to conclude that a tight ligature above the wound would help to reduce the amount of venom that reached the heart. Redi’s work on snakebites marked the beginning of experimental toxicology.
In 1668 Redi completed what is viewed as his masterpiece, Esperienze intorno alla generazione degl’insetti , and sent it to Carlo Dati, a Florentine nobleman and secretary of the Accademia del Cimento . In this work, Redi provided experimental evidence against spontaneous generation in insects, an Aristotelian idea that at the time was widely accepted. This popular idea possibly arose from the observations that worms and other parasites seemed to simply “emerge” from decaying plants and animals. However, using microscopy, Redi discovered an intricate system of reproduction in insects. He examined the egg-producing apparatus and observed the structures of the eggs of a variety of insect species. As a consequence of this work, Redi sought to challenge the doctrine of spontaneous generation in lower animals. He concluded in Esperienze that animals more likely “are born from the eggs laid by their mothers, fertilized by coitus” than through spontaneous generation.
In 1684 Redi published his parasitological treatise, Osservazioni intorno agli animali viventi, che si trovano negli animali viventi . Redi’s research on the generation of insects and parasitology was extended by physician Giovanni Cosimo Bonomo and apothecary Giacinto Cestoni, and their results were presented in Osservazioni intorno a’ pellicelli del corpo umano in 1687. After years of work on toxicology, parasitology, and entomology, Francesco Redi died on 1 March 1697 in Pisa, Italy.
- Belloni, Luigi. “Redi, Francesco.” Dictionary of Scientific Biography , 11: 341–43.
- Cobb, Matthew. The Egg and Sperm Race . London: Free Press, 2006.
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
- Advertise with Us
- Privacy Policy
Pasteur Brewing Louis Pasteur – Science, Health, and Brewing
Louis pasteur, francesco redi, and spontaneous generation for kids.
Where do cells come from? If a cut of meat is let out, over time it will putrefy and begin to teem with microorganisms and possibly with larger organisms like maggots. Prior to the mid-to-late 19th century, the origin of microorganisms in decaying matter was in question. Some maintained that microbes arose from other microbes that landed on the food from the air. Other supported the hypothesis of spontaneous generation, which states that living organisms can arise spontaneously from nonliving matter.
Redi’s Experiment
In the 1600’s, Francesco Redi sought to test the hypothesis of spontaneous generation by applying what came to be known as the scientific method–a process of making observations, asking questions, formulating a hypothesis and designing experiments to test the hypotheses.
Redi and others observed that flies and then maggots could be seen around pieces of meat that were left out in the open. He therefore asked the following questions: Where do flies come from? Is the rotting meat transformed into the flies? From these questions, Redi formulated the hypothesis that only flies can make flies, and that rotting meat cannot be transformed into flies.
Redi sought to test his hypothesis by performing the following experiment. He placed pieces of meat into three glass jars. The first jar was left open, the second was covered with a loos netting, and the third was completely sealed. All jars were exposed to flies in the surrounding room. Redi predicted that if meat could not be transformed into flies, then the sealed containers should not produce either maggots or flies. Whereas if the meat can be so transformed, then the sealed jar should also develop maggots and flies.
Redi recorded the presence or absence of flies and maggots in each of the three types of jars. As he predicted, neither flies nor maggots were found in the sealed jars, whereas in the open jars, maggots and flies were abundant. In the jars covered with netting, maggots were found within the netting itself, but not on the meat inside the jar. Redi concluded that meat could not transform into flies, only flies could produce flies. The theory of spontaneous generation could not be supported and was therefore incorrect.
Pasteur’s Experiment
Unfortunately, Redi’s experiment did not convince everyone. Some argued that while spontaneous generation might not apply to larger organisms like maggots and flies, it might still be applicable to smaller microbes. The question was finally answered definitively in the late 1800s by Louis Pasteur, in his now classic experiment.
Pasteur’s hypothesis was that if cells could arise from nonliving substances, then they should appear spontaneously in sterile broth.
To test his hypothesis, he created two treatment groups: a broth that was exposed to a source of microbial cells, and a broth that was not. For his control treatment, Pasteur used a straight-necked flask that allowed particles in the air to fall into the broth stored in the flask. For his experimental treatment, Pasteur used a swan-necked flask. The neck shaped and length assured that no cells could enter the broth from the air.
By changing a single variable–the shape of the flask neck–Pasteur was able to conclude that cells were not generated spontaneously but were actually entering the broth from the surrounding air. Microorganisms, carried by dust particles, fell into the straight-necked flask. However, the swan neck trapped the particles, preventing cells from entering the broth.
Related Articles
Louis Pasteur Activity Book and Video for Kids
Pasteur Swan Neck Flask Experiment
Louis Pasteur Experiment: Grow Your Own Bacteria
Louis Pasteur Word Search
This word search is great for kids to learn some of the key terms used …
Leave a Reply
You must be logged in to post a comment.
 Alexander Oparin ResourcesSee the additional sources and recommended reading list below, or check the physics books page for a full list. Whenever possible, I linked to books with my amazon affiliate code, and as an Amazon Associate I earn from qualifying purchases. Purchasing from these links helps to keep the website running, and I am grateful for your support! |
IMAGES
VIDEO
COMMENTS
Maggots and flies don't spontaneously generate from rotting meat Prior to Francesco Redi's experiment in 1668, it was supposed that life could be generated spontaneously, that maggots could simply appear on a piece of rotting meat, for instance. In fact, this was a theory that had been around since the time of Aristotle (and he died in 322 BC, so it was an idea nearly 2000 years old). Redi ...
Redi experiment (1665) As late as the 17th century, some biologists thought that some simpler forms of life were generated by spontaneous generation from inanimate matter. Although this was rejected for more complex forms such as mice, which were observed to be born from mother mice after they copulated with father mice, there remained doubt for such things as insects whose reproductive cycle ...
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 ...
Redi's Experiment and Needham's Rebuttal. In 1668, Francesco Redi, an Italian scientist, designed a scientific experiment to test the spontaneous creation of maggots by placing fresh meat in each of two different jars. One jar was left open; the other was covered with a cloth. Days later, the open jar contained maggots, whereas the covered jar ...
Francesco Redi (born Feb. 18, 1626, Arezzo, Italy—died March 1, 1697, Pisa) was an Italian physician and poet who demonstrated that the presence of maggots in putrefying meat does not result from spontaneous generation but from eggs laid on the meat by flies.. He read in the book on generation by William Harvey a speculation that vermin such as insects, worms, and frogs do not arise ...
The Francesco Redi Experiment. Francesco Redi was able to disprove the theory that maggots could be spontaneously generated from meat using a controlled experiment. Spontaneous generation, the theory that life forms can be generated from inanimate objects, had been around since at least the time of Aristotle.
Figure 3.1.3 3.1. 3: (a) French scientist Louis Pasteur, who definitively refuted the long-disputed theory of spontaneous generation. (b) The unique swan-neck feature of the flasks used in Pasteur's experiment allowed air to enter the flask but prevented the entry of bacterial and fungal spores. (c) Pasteur's experiment consisted of two parts.
Redi devised and performed the now-famous experiment in which six jars, half left in open air and half covered with fine gauze that permitted air circulation but kept out flies, were filled with either an unknown object, a dead fish, or raw veal. The fish and veal rotted in both groups, but maggots only formed in the jars open to air.
6. Francesco redi experiment conclusion. The aim of Redi's experiment was to test the hypothesis that " maggots could spontaneously arise from decaying meat. Three wide-mouthed glass jars with lids: Redi used three glass jars to hold the meat, one of which was left open to the air, one covered with gauze, and one sealed completely.
Francesco Redi (18 February 1626 - 1 March 1697) was an Italian physician, naturalist, biologist, and poet. He is referred to as the "founder of experimental biology", and as the "father of modern parasitology". He was the first person to challenge the theory of spontaneous generation by demonstrating that maggots come from eggs of flies.. Having a doctoral degree in both medicine and ...
What is Redi's conclusion in experiment? John Needham is credited for tests that gave bearing to the belief of spontaneous generation, or the sudden creation of life. His tests involved boiling ...
Francesco Redi was born in Tuscany, Italy on February 18, 1626. In 1647, at the age of 21, Redi graduated with his doctoral degree in medicine and philosophy from the University of Pisa. After ...
To test our hypothesis, we set up an experiment like the one Redi carried out in 1668. We took three 1000-L glass beakers and put two 2-inch cubes of raw beef in the bottom of each beaker. The beef had been purchased 1 week before the experiment was set up, and had been refrigerated until the setup day.
Redi's Experiment. Francesco Redi is famous for his demonstration of the use of controlled experiments and his challenge to the theory of spontaneous generation. In this experiment Francesco took eight jars, placed meat in all the jars, but covered four of the eight jars with cotton fabric weave. A few days later maggots developed in the open ...
Francesco Redi, son of Florentine physician Cecilia de' Ghinci and Gregorio Redi, was born in Arezzo, Italy, on 18 February 1626. He studied philosophy and medicine at the University of Pisa, graduating on 1 May 1647. A year later, Redi moved to Florence and registered at the Collegio Medico. There he served at the Medici Court as both the head physician and superintendent of the ducal ...
Redi's Esperienze intorno alla generazione degl'insetti (1668) was pub- ... At last he came to the conclusion that "serpents ... are born only of coitus; all other serpentine generations ... of experiment with all sorts of other meat from mammals, birds and frogs, both raw and cooked. He always obtained the same result.
A key event in the conceptual development of modern biology was the publication of Francesco Redi's (1626-1697) paper entitled "Experiments on the Generation of Insects" in 1668. He hypothesized that spontaneous generation did not occur. ... this objection would invalidate Pasteur's conclusions. Clearly an experiment to address that ...
Redi's Experiment and Needham's Rebuttal In 1668, Francesco Redi, an Italian scientist, designed a scientific experiment to test the spontaneous creation of maggots by placing fresh meat in each of two different jars. One jar was left open; the ... Name several elements included in a well-written conclusion.
Francesco Redi's experimental setup consisted of an open container, a container sealed with a cork top, and a container covered in mesh that let in air but not flies. ... (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 ...
The idea of a controlled experiment is that two tests are identical in every aspect, except for one factor. When carried out simultaneously, the hypothesis is that this differing factor (called the "manipulated variable") is the cause of the different results in each experiment. Redi's Experiment Explained. 1.
Redi's Experiment. In the 1600's, Francesco Redi sought to test the hypothesis of spontaneous generation by applying what came to be known as the scientific method-a process of making observations, asking questions, formulating a hypothesis and designing experiments to test the hypotheses. Redi and others observed that flies and then ...
Antonie van Leeuwenhoek. Traditional religion attributed the origin of life to deities who created the natural world. Spontaneous generation, the first naturalistic theory of abiogenesis, goes back to Aristotle and ancient Greek philosophy, and continued to have support in Western scholarship until the 19th century. The theory held that "lower" animals are generated by decaying organic substances.
Alexander Oparin was a Russian biochemist, notable for his contributions to the theory of the origin of life on Earth, and particularly for the "primordial soup" theory of the evolution of life from carbon-based molecules.Oparin also devoted considerable effort to enzymology and helped to develop the foundations of industrial biochemistry in the USSR.