Answer:
Louis Pasteur disproved the theory of spontaneous generation by swan neck experiment.
Step-by-step explanation:
He showed that in the flask which was open to air, new living organisms arose while no life appeared in the flask which was not open to air (in the flask with swan neck). He showed that life did not come from the killed yeast in the flask with curved neck where as in the other flask which was open to air, new organisms arose from killed yeast.
The purpose was not to show that new organisms came from killed yeast but to explain that it was actually the "air" in which living organisms were present that entered the flask when it was kept open to air. Thus life comes from pre-existing living organisms.