Question

what where Redi and Spallanzani's experiment trying to prove or disprove? What theory were they testing in order to conduct those two experiment?

Answer 1

Redi was an Italian physician who performed an experiment of disproving the theory of spontaneous generation. Spontaneous generation theory says that life can originate from nonliving substances. It was proposed by Aristotle. In the experiment, the physician tested the formation of maggots in a container with a piece of meat in it. He tested it in condition, cork sealed condition, and gauze covered condition. He found the maggots formation occur only in the case when the container was open. No formation of maggots in the other containers was disproving the theory of spontaneous generation.

Later in 1745, John Needham performed an experiment in which he boiled plant and animal matter infused broth briefly to kill the pre-existing microbes. He sealed the flask and noticed cloudy broth after a few days. The broth had microbial colonies. From this experiment, he supported the theory of spontaneous generation. However, it was likely that all microbes were not killed during the boiling process.

Lazzaro Spallanzani contradicted Needham’s conclusions by performing hundreds of experiment using heated broth and found that spontaneous growth was absent unless the flasks were open as in open jars microbes can come from air.

Hence, both Redi and Spallanzani were disproving the theory of spontaneous generation.