Swan-neck flask of Pasteur

This led to one of the most famous experiment of microbial history, the “Swan-neck flask” experiment by Pasteur. Please refer the figure for the shape of the flask. Now organic infusion inside the flask was made sterile by heating. Indeed there was no microbial growth in the organic infusion as the microbes cannot ascend the bent neck of the flask. But when the neck is broken or the sterile liquid becomes densely populated with microorganisms. Pasteur’s experiments made it clear that the living organisms are evenly distributed throughout the atmosphere. Thus "Germ Theory" was established and gained over "Spontaneous generation" theory.