He conducted a series of experiments in the mid-1800s using swan-neck flasks. He boiled beef broth in the flasks, which sterilized the broth. Some flasks had their necks bent into an S-shape, trapping airborne microbes. Others had their necks broken, exposing the broth to the air.
He observed that the broth in the swan-neck flasks remained clear, while the broth in the broken-neck flasks became cloudy due to microbial growth. This demonstrated that the microbes were not spontaneously generated in the broth, but rather came from the air.
This experiment was a crucial step in disproving the theory of spontaneous generation and supporting the theory of biogenesis, which states that all living organisms originate from pre-existing living organisms.
