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Jhon Needham
John Needham was an English naturalist and Roman Catholic priest who lived in the 18th century. He wrote several works on natural history and philosophy, including "An Account of Some New Microscopical Discoveries" and "Experiments upon Vegetables". His work on spontaneous generation and his dispute with Lazzaro Spallanzani contributed to the development of the germ theory of disease. -
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Lazzaro Spallanzani
Lazzaro Spallanzani's experiment in the 18th century involved boiling beef broth and sealing it in flasks, which prevented the growth of microorganisms. His findings challenged the theory of spontaneous generation and supported the theory of biogenesis, which states that living organisms can only arise from other living organisms. Spallanzani's work highlighted the importance of sterilization through heating to prevent the growth of microorganisms. -
Needham's rebuttal
In response to Redi's experiment, John Needham conducted an experiment in which he boiled meat broth in a sealed flask and observed the growth of microorganisms. Needham claimed that this experiment supported spontaneous generation, as the microorganisms seemed to appear without any visible source. However, later experiments showed flaws in Needham's methods, such as not boiling the flask long enough to kill all microorganisms or allowing air to enter the flask after boiling. -
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Louis Pasteur
Louis Pasteur was a French microbiologist and chemist who lived in the 19th century. He made significant contributions to the fields of microbiology and immunology, including the development of pasteurization, a process to prevent the growth of harmful microorganisms in food and drink. His work on germ theory, vaccination, and fermentation led to numerous breakthroughs in medicine and chemistry. -
Pasteur, spontaneous generation
Louis Pasteur's experiments in the mid-19th century provided conclusive evidence against the theory of spontaneous generation. He used curved-neck flasks to trap microorganisms and prevent air from entering. When the flasks were tipped and the necks exposed to air, microorganisms grew, but not when the necks remained sealed. Pasteur's work showed that microorganisms only arise from pre-existing microorganisms and laid the foundation for the germ theory of disease. -
Criticism from Spallanzani
Lazzaro Spallanzani criticized John Needham's experiment on spontaneous generation, arguing that the experiment was flawed and air was the source of the microorganisms. He conducted his own experiments where he sealed flasks of broth before boiling, which resulted in no growth of microorganisms. Spallanzani also criticized Needham for not boiling his flasks for long enough and for exposing the flasks to air, which could introduce microorganisms. -
Francesco Redi and his experiments
Redi did an experiment in the 17th century to disprove the theory of spontan. generation, which suggested that life could arise from non-living matter. He used three jars of meat, one left open, one sealed, and one covered with gauze. Maggots appeared only in the open jar, leading Redi to conclude that they were produced by flies laying eggs on the meat. Redi's experiment helped disprove spontaneous generation and paved the way for further scientific discoveries about the role of microorganisms.