How did Louis Pasteur experimentally disprove the concept of spontaneous generation?

Louis Pasteur's work on disproving spontaneous generation is pivotal in the history of microbiology. He conducted a series of important experiments using flasks that had long, curved necks, often referred to as swan-neck flasks. These designs allowed air to enter the flask while preventing dust and microorganisms from contaminating the nutrient broth within.

By leaving the broth exposed to the air in these specially designed flasks, Pasteur demonstrated that, when the necks remained intact, no microbial growth occurred in the broth. This suggested that microorganisms from the air were the source of contamination, rather than the broth itself spontaneously generating life. When he broke the necks of the flasks, allowing direct exposure to the air, microbial growth did occur, further supporting the idea that microorganisms were coming from the environment, not arising spontaneously.

This demonstrated that life does not just appear from non-living matter under the conditions he tested, thereby providing strong experimental evidence against the theory of spontaneous generation. The structure of the flask and its maintenance of a barrier to contamination were critical elements in his argument. Other methods or modifications to the flask, such as simply sealing it from air, would not have effectively addressed the source of microbial life that motivated his experiments. Through this work