Spallanzani successfully proved the case against spontaneous generation theory. But the problem is that faulty experiments were still performed & as a result the controversy remained. Francois Apart in the beginning of 19th century made an interesting experiment. Instead of organic infusions he used food stuffs in the air tight bottle and heated it. Thus he was successful in storing or preserving food stuffs for long time which was earlier impossible. This was a practical application of Spallanzani’s experiment and known as canning or “Apertization” (on behalf of Apart) and used extensively to preserve food in that period.
Then another problem or controversy came in front regarding proving the presence of germs against the spontaneous theory. In late 18th century Oxygen was discovered by Priestley, Cavendish & Lavoisier and soon it was found that it is essential for the existence of living being. So many thought that due to the hermetic sealing used by Spallanzani or Apart; the oxygen supply was cut off & that was the reason of no microbial growth in the organic infusion; not the presence of germs in the air. This is really a big problem and is very difficult to deal with. Later it was proved that if germ free air is passed through the pre heated organic infusion then there will be no decomposition of the organic infusion even in the presence of oxygen.