{"id":141,"date":"2016-11-04T03:32:43","date_gmt":"2016-11-04T03:32:43","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/microbiology\/?post_type=chapter&#038;p=141"},"modified":"2018-07-11T18:26:25","modified_gmt":"2018-07-11T18:26:25","slug":"spontaneous-generation","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/chapter\/spontaneous-generation\/","title":{"raw":"Spontaneous Generation","rendered":"Spontaneous Generation"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\n<ul>\r\n \t<li>Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms<\/li>\r\n \t<li>Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generations.<\/li>\r\n<\/ul>\r\n<\/div>\r\nHumans 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.\r\n<h2>The Theory of Spontaneous Generation<\/h2>\r\nThe Greek philosopher Aristotle (384\u2013322 BC) was one of the earliest recorded scholars to articulate the theory of <strong>spontaneous generation<\/strong>, the notion that life can arise from nonliving matter. <strong>Aristotle<\/strong> proposed that life arose from nonliving material if the material contained <em>pneuma<\/em> (\"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.[footnote] K. Zwier. \"Aristotle on Spontaneous Generation.\" <a href=\"http:\/\/www.sju.edu\/int\/academics\/cas\/resources\/gppc\/pdf\/Karen%20R.%20Zwier.pdf\" target=\"_blank\" rel=\"noopener\">http:\/\/www.sju.edu\/int\/academics\/cas\/resources\/gppc\/pdf\/Karen%20R.%20Zwier.pdf<\/a>[\/footnote]\r\n\r\nThis theory persisted into the seventeenth\u00a0century, 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 <strong>van Helmont<\/strong>, a seventeenth 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.\r\n\r\nHowever, one of van Helmont\u2019s contemporaries, Italian physician Francesco <strong>Redi<\/strong> (1626\u20131697), 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 1). 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.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1049\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1094\/2016\/11\/03153743\/OSC_Microbio_03_01_Rediexpt.jpg\" alt=\"An open container with meat has flies and the formation of maggots in meat. A cork-sealed container of meat has no flies and no formation of maggots in meat. A gauze covered container of meat has flies and maggots on the surface of the gauze but no maggots in the meat.\" width=\"1049\" height=\"562\" \/> Figure 1. Francesco Redi\u2019s 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. Maggots only appeared on the meat in the open container. However, maggots were also found on the gauze of the gauze-covered container.[\/caption]\r\n\r\nIn 1745, John Needham (1713\u20131781) 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.[footnote] E. Capanna. \"Lazzaro Spallanzani: At the Roots of Modern Biology.\" <em>Journal of Experimental Zoology<\/em> 285 no. 3 (1999):178\u2013196.[\/footnote]\u00a0He 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.\r\n\r\nLazzaro Spallanzani (1729\u20131799) did not agree with Needham\u2019s conclusions, however, and performed hundreds of carefully executed experiments using heated broth.[footnote]R. Mancini, M. Nigro, G. Ippolito. \"Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.\" <em>Le Infezioni in Medicina<\/em> 15 no. 3 (2007):199\u2013206.[\/footnote]\u00a0As in Needham\u2019s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani\u2019s 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\u2019s findings, Needham argued that life originates from a \"life force\" that was destroyed during Spallanzani\u2019s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation (Figure 2).\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Think about It<\/h3>\r\n<ul>\r\n \t<li>Describe the theory of spontaneous generation and some of the arguments used to support it.<\/li>\r\n \t<li>Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<h2>Disproving Spontaneous Generation<\/h2>\r\nThe debate over spontaneous generation continued well into the nineteenth\u00a0century, 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.\r\n\r\nLater, Pasteur made a series of flasks with long, twisted necks (\"swan-neck\" flasks), in which he boiled broth to sterilize it (Figure 3). 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\u2019 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.\r\n\r\nPasteur\u2019s 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 \"<em>Omne vivum ex vivo<\/em>\" (\"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.\"[footnote]R. Vallery-Radot. <em>The Life of Pasteur<\/em>, trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142.[\/footnote]\u00a0To Pasteur\u2019s credit, it never has.\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"650\"]<img class=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1094\/2016\/11\/03153750\/OSC_Microbio_03_01_Pasteur.jpg\" alt=\"a) Photo of Louis Pasteur b) Photo of Pasteur\u2019s flask \u2013 a round flask that is only opened to the outside through a long S-shaped tube. c) A drawing of Pasteur\u2019s experiment. The top diagram shows the swan-neck flask from (b) containing broth that is being boiled to kill microorganisms in the broth. After the boiling process the cooled flask remains sterile because the curve of the flask prevents outside air from entering the flask. So, no contamination occurs. The bottom diagram shows the same flask being boiled. Next, the swan-neck is removed and the flask is opened to the environment. When the neck of the flask is broken off, bacteria reach the sterile broth and organism growth occurs. This is seen as cloudiness in the broth.\" width=\"650\" height=\"660\" \/> Figure 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\u2019s experiment allowed air to enter the flask but prevented the entry of bacterial and fungal spores. (c) Pasteur\u2019s experiment consisted of two parts. In the first part, the broth in the flask was boiled to sterilize it. When this broth was cooled, it remained free of contamination. In the second part of the experiment, the flask was boiled and then the neck was broken off. The broth in this flask became contaminated. (credit b: modification of work by \"Wellcome Images\"\/Wikimedia Commons)[\/caption]\r\n\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Think about It<\/h3>\r\n<ul>\r\n \t<li>How did Pasteur\u2019s experimental design allow air, but not microbes, to enter, and why was this important?<\/li>\r\n \t<li>What was the control group in Pasteur\u2019s experiment and what did it show?<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Key Concepts and Summary<\/h3>\r\n<ul>\r\n \t<li>The theory of <strong>spontaneous generation<\/strong> states that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks.<\/li>\r\n \t<li>Experimentation by Francesco Redi in the seventeenth 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.<\/li>\r\n \t<li>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.\"<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Multiple Choice<\/h3>\r\nWhich of the following individuals argued in favor of the theory of spontaneous generation?\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>Francesco Redi<\/li>\r\n \t<li>Louis Pasteur<\/li>\r\n \t<li>John Needham<\/li>\r\n \t<li>Lazzaro Spallanzani<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"255532\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"255532\"]Answer c. John Needham argued in favor of the theory of spontaneous generation.[\/hidden-answer]\r\n\r\nWhich of the following individuals is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flask?\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>Aristotle<\/li>\r\n \t<li>Jan Baptista van Helmont<\/li>\r\n \t<li>John Needham<\/li>\r\n \t<li>Louis Pasteur<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"900159\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"900159\"]Answer d. Louis Pasteur is credited for definitively refuting the theory of spontaneous generation.[\/hidden-answer]\r\n\r\nWhich of the following experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation.\r\n<ol style=\"list-style-type: lower-alpha\">\r\n \t<li>Aristotle<\/li>\r\n \t<li>Lazzaro Spallanzani<\/li>\r\n \t<li>Antonie van Leeuwenhoek<\/li>\r\n \t<li>Francesco Redi<\/li>\r\n<\/ol>\r\n[reveal-answer q=\"329792\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"329792\"]Answer c. Antonie van Leeuwenhoek\u00a0experimented with raw meat, maggots, and flies.[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Fill in the Blank<\/h3>\r\nThe assertion that \"life only comes from life\" was stated by Louis Pasteur in regard to his experiments that definitively refuted the theory of ___________.\r\n\r\n[reveal-answer q=\"666223\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"666223\"]The assertion that \"life only comes from life\" was stated by Louis Pasteur in regard to his experiments that definitively refuted the theory of <strong>spontaneous generation<\/strong>.[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>True\/False<\/h3>\r\nExposure to air is necessary for microbial growth.\r\n\r\n[reveal-answer q=\"594140\"]Show Answer[\/reveal-answer]\r\n[hidden-answer a=\"594140\"]False[\/hidden-answer]\r\n\r\n<\/div>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Think about It<\/h3>\r\n<ol>\r\n \t<li>Explain in your own words Pasteur\u2019s swan-neck flask experiment.<\/li>\r\n \t<li>Explain why the experiments of Needham and Spallanzani yielded in different results even though they used similar methodologies.<\/li>\r\n \t<li>What would the results of Pasteur\u2019s swan-neck flask experiment have looked like if they supported the theory of spontaneous generation?<\/li>\r\n<\/ol>\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<ul>\n<li>Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms<\/li>\n<li>Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generations.<\/li>\n<\/ul>\n<\/div>\n<p>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.<\/p>\n<h2>The Theory of Spontaneous Generation<\/h2>\n<p>The Greek philosopher Aristotle (384\u2013322 BC) was one of the earliest recorded scholars to articulate the theory of <strong>spontaneous generation<\/strong>, the notion that life can arise from nonliving matter. <strong>Aristotle<\/strong> proposed that life arose from nonliving material if the material contained <em>pneuma<\/em> (&#8220;vital heat&#8221;). 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.<a class=\"footnote\" title=\"K. Zwier. &quot;Aristotle on Spontaneous Generation.&quot; http:\/\/www.sju.edu\/int\/academics\/cas\/resources\/gppc\/pdf\/Karen%20R.%20Zwier.pdf\" id=\"return-footnote-141-1\" href=\"#footnote-141-1\" aria-label=\"Footnote 1\"><sup class=\"footnote\">[1]<\/sup><\/a><\/p>\n<p>This theory persisted into the seventeenth\u00a0century, 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 <strong>van Helmont<\/strong>, a seventeenth 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.<\/p>\n<p>However, one of van Helmont\u2019s contemporaries, Italian physician Francesco <strong>Redi<\/strong> (1626\u20131697), 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 1). 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.<\/p>\n<div style=\"width: 1059px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1094\/2016\/11\/03153743\/OSC_Microbio_03_01_Rediexpt.jpg\" alt=\"An open container with meat has flies and the formation of maggots in meat. A cork-sealed container of meat has no flies and no formation of maggots in meat. A gauze covered container of meat has flies and maggots on the surface of the gauze but no maggots in the meat.\" width=\"1049\" height=\"562\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 1. Francesco Redi\u2019s 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. Maggots only appeared on the meat in the open container. However, maggots were also found on the gauze of the gauze-covered container.<\/p>\n<\/div>\n<p>In 1745, John Needham (1713\u20131781) 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.<a class=\"footnote\" title=\"E. Capanna. &quot;Lazzaro Spallanzani: At the Roots of Modern Biology.&quot; Journal of Experimental Zoology 285 no. 3 (1999):178\u2013196.\" id=\"return-footnote-141-2\" href=\"#footnote-141-2\" aria-label=\"Footnote 2\"><sup class=\"footnote\">[2]<\/sup><\/a>\u00a0He 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.<\/p>\n<p>Lazzaro Spallanzani (1729\u20131799) did not agree with Needham\u2019s conclusions, however, and performed hundreds of carefully executed experiments using heated broth.<a class=\"footnote\" title=\"R. Mancini, M. Nigro, G. Ippolito. &quot;Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.&quot; Le Infezioni in Medicina 15 no. 3 (2007):199\u2013206.\" id=\"return-footnote-141-3\" href=\"#footnote-141-3\" aria-label=\"Footnote 3\"><sup class=\"footnote\">[3]<\/sup><\/a>\u00a0As in Needham\u2019s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani\u2019s 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\u2019s findings, Needham argued that life originates from a &#8220;life force&#8221; that was destroyed during Spallanzani\u2019s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation (Figure 2).<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Think about It<\/h3>\n<ul>\n<li>Describe the theory of spontaneous generation and some of the arguments used to support it.<\/li>\n<li>Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.<\/li>\n<\/ul>\n<\/div>\n<h2>Disproving Spontaneous Generation<\/h2>\n<p>The debate over spontaneous generation continued well into the nineteenth\u00a0century, 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 &#8220;life force&#8221; to the broth but rather airborne microorganisms.<\/p>\n<p>Later, Pasteur made a series of flasks with long, twisted necks (&#8220;swan-neck&#8221; flasks), in which he boiled broth to sterilize it (Figure 3). 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\u2019 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.<\/p>\n<p>Pasteur\u2019s 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 &#8220;<em>Omne vivum ex vivo<\/em>&#8221; (&#8220;Life only comes from life&#8221;). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that &#8220;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.&#8221;<a class=\"footnote\" title=\"R. Vallery-Radot. The Life of Pasteur, trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142.\" id=\"return-footnote-141-4\" href=\"#footnote-141-4\" aria-label=\"Footnote 4\"><sup class=\"footnote\">[4]<\/sup><\/a>\u00a0To Pasteur\u2019s credit, it never has.<\/p>\n<div style=\"width: 660px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1094\/2016\/11\/03153750\/OSC_Microbio_03_01_Pasteur.jpg\" alt=\"a) Photo of Louis Pasteur b) Photo of Pasteur\u2019s flask \u2013 a round flask that is only opened to the outside through a long S-shaped tube. c) A drawing of Pasteur\u2019s experiment. The top diagram shows the swan-neck flask from (b) containing broth that is being boiled to kill microorganisms in the broth. After the boiling process the cooled flask remains sterile because the curve of the flask prevents outside air from entering the flask. So, no contamination occurs. The bottom diagram shows the same flask being boiled. Next, the swan-neck is removed and the flask is opened to the environment. When the neck of the flask is broken off, bacteria reach the sterile broth and organism growth occurs. This is seen as cloudiness in the broth.\" width=\"650\" height=\"660\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 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\u2019s experiment allowed air to enter the flask but prevented the entry of bacterial and fungal spores. (c) Pasteur\u2019s experiment consisted of two parts. In the first part, the broth in the flask was boiled to sterilize it. When this broth was cooled, it remained free of contamination. In the second part of the experiment, the flask was boiled and then the neck was broken off. The broth in this flask became contaminated. (credit b: modification of work by &#8220;Wellcome Images&#8221;\/Wikimedia Commons)<\/p>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Think about It<\/h3>\n<ul>\n<li>How did Pasteur\u2019s experimental design allow air, but not microbes, to enter, and why was this important?<\/li>\n<li>What was the control group in Pasteur\u2019s experiment and what did it show?<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Key Concepts and Summary<\/h3>\n<ul>\n<li>The theory of <strong>spontaneous generation<\/strong> states that life arose from nonliving matter. It was a long-held belief dating back to Aristotle and the ancient Greeks.<\/li>\n<li>Experimentation by Francesco Redi in the seventeenth 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.<\/li>\n<li>Louis Pasteur is credited with conclusively disproving the theory of spontaneous generation with his famous swan-neck flask experiment. He subsequently proposed that &#8220;life only comes from life.&#8221;<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Multiple Choice<\/h3>\n<p>Which of the following individuals argued in favor of the theory of spontaneous generation?<\/p>\n<ol style=\"list-style-type: lower-alpha\">\n<li>Francesco Redi<\/li>\n<li>Louis Pasteur<\/li>\n<li>John Needham<\/li>\n<li>Lazzaro Spallanzani<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q255532\">Show Answer<\/span><\/p>\n<div id=\"q255532\" class=\"hidden-answer\" style=\"display: none\">Answer c. John Needham argued in favor of the theory of spontaneous generation.<\/div>\n<\/div>\n<p>Which of the following individuals is credited for definitively refuting the theory of spontaneous generation using broth in swan-neck flask?<\/p>\n<ol style=\"list-style-type: lower-alpha\">\n<li>Aristotle<\/li>\n<li>Jan Baptista van Helmont<\/li>\n<li>John Needham<\/li>\n<li>Louis Pasteur<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q900159\">Show Answer<\/span><\/p>\n<div id=\"q900159\" class=\"hidden-answer\" style=\"display: none\">Answer d. Louis Pasteur is credited for definitively refuting the theory of spontaneous generation.<\/div>\n<\/div>\n<p>Which of the following experimented with raw meat, maggots, and flies in an attempt to disprove the theory of spontaneous generation.<\/p>\n<ol style=\"list-style-type: lower-alpha\">\n<li>Aristotle<\/li>\n<li>Lazzaro Spallanzani<\/li>\n<li>Antonie van Leeuwenhoek<\/li>\n<li>Francesco Redi<\/li>\n<\/ol>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q329792\">Show Answer<\/span><\/p>\n<div id=\"q329792\" class=\"hidden-answer\" style=\"display: none\">Answer c. Antonie van Leeuwenhoek\u00a0experimented with raw meat, maggots, and flies.<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Fill in the Blank<\/h3>\n<p>The assertion that &#8220;life only comes from life&#8221; was stated by Louis Pasteur in regard to his experiments that definitively refuted the theory of ___________.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q666223\">Show Answer<\/span><\/p>\n<div id=\"q666223\" class=\"hidden-answer\" style=\"display: none\">The assertion that &#8220;life only comes from life&#8221; was stated by Louis Pasteur in regard to his experiments that definitively refuted the theory of <strong>spontaneous generation<\/strong>.<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>True\/False<\/h3>\n<p>Exposure to air is necessary for microbial growth.<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q594140\">Show Answer<\/span><\/p>\n<div id=\"q594140\" class=\"hidden-answer\" style=\"display: none\">False<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox key-takeaways\">\n<h3>Think about It<\/h3>\n<ol>\n<li>Explain in your own words Pasteur\u2019s swan-neck flask experiment.<\/li>\n<li>Explain why the experiments of Needham and Spallanzani yielded in different results even though they used similar methodologies.<\/li>\n<li>What would the results of Pasteur\u2019s swan-neck flask experiment have looked like if they supported the theory of spontaneous generation?<\/li>\n<\/ol>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-141\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>OpenStax Microbiology. <strong>Provided by<\/strong>: OpenStax CNX. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/e42bd376-624b-4c0f-972f-e0c57998e765@4.2\">http:\/\/cnx.org\/contents\/e42bd376-624b-4c0f-972f-e0c57998e765@4.2<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Download for free at http:\/\/cnx.org\/contents\/e42bd376-624b-4c0f-972f-e0c57998e765@4.2<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section><hr class=\"before-footnotes clear\" \/><div class=\"footnotes\"><ol><li id=\"footnote-141-1\"> K. Zwier. \"Aristotle on Spontaneous Generation.\" <a href=\"http:\/\/www.sju.edu\/int\/academics\/cas\/resources\/gppc\/pdf\/Karen%20R.%20Zwier.pdf\" target=\"_blank\" rel=\"noopener\">http:\/\/www.sju.edu\/int\/academics\/cas\/resources\/gppc\/pdf\/Karen%20R.%20Zwier.pdf<\/a> <a href=\"#return-footnote-141-1\" class=\"return-footnote\" aria-label=\"Return to footnote 1\">&crarr;<\/a><\/li><li id=\"footnote-141-2\"> E. Capanna. \"Lazzaro Spallanzani: At the Roots of Modern Biology.\" <em>Journal of Experimental Zoology<\/em> 285 no. 3 (1999):178\u2013196. <a href=\"#return-footnote-141-2\" class=\"return-footnote\" aria-label=\"Return to footnote 2\">&crarr;<\/a><\/li><li id=\"footnote-141-3\">R. Mancini, M. Nigro, G. Ippolito. \"Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.\" <em>Le Infezioni in Medicina<\/em> 15 no. 3 (2007):199\u2013206. <a href=\"#return-footnote-141-3\" class=\"return-footnote\" aria-label=\"Return to footnote 3\">&crarr;<\/a><\/li><li id=\"footnote-141-4\">R. Vallery-Radot. <em>The Life of Pasteur<\/em>, trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142. <a href=\"#return-footnote-141-4\" class=\"return-footnote\" aria-label=\"Return to footnote 4\">&crarr;<\/a><\/li><\/ol><\/div>","protected":false},"author":17,"menu_order":3,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"OpenStax Microbiology\",\"author\":\"\",\"organization\":\"OpenStax CNX\",\"url\":\"http:\/\/cnx.org\/contents\/e42bd376-624b-4c0f-972f-e0c57998e765@4.2\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at http:\/\/cnx.org\/contents\/e42bd376-624b-4c0f-972f-e0c57998e765@4.2\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-141","chapter","type-chapter","status-publish","hentry"],"part":51,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/chapters\/141","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":8,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/chapters\/141\/revisions"}],"predecessor-version":[{"id":2132,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/chapters\/141\/revisions\/2132"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/parts\/51"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/chapters\/141\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/wp\/v2\/media?parent=141"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/pressbooks\/v2\/chapter-type?post=141"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/wp\/v2\/contributor?post=141"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-mcc-microbiology\/wp-json\/wp\/v2\/license?post=141"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}