BIO

Francesco Redi

Feb 18, 1626

1626-1697
He was an Italian physician and poet
He made the first serious attack on the idea of spontaneous generation in 1668. At that time, it was widely held that maggots arose spontaneously in rotting meat. To achieve his goal of proving spontaneous generation to be wrong, he set out a controlled experiment such as the one described in this figure:

John Needham

1745

1713-1781
John Needham carried out an experiment: he boiled meat broth to destroy pre-existing organisms and placed it in a container that was not properly sealed, since according to his theory, air was needed for this to take place. After, he observed colonies in the container, which did not contradict the theory of spontaneous generation.
He argued that air was essential for life, including the spontaneous generation of microorganisms, and this had been excluded in the experiments of Lazzaro.

Lazzaro Spallanzani

1780

1729–1799
He was Italian priest, did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth.
Spallanzani poured broth into flasks and sealed them. Next, he boiled the flasks for a long time, to kill present microorganisms.
After some time, the broth did not have any trace of life.
Spallanzani concluded that spontaneous generation was false and microbes came from contaminated air.

Louis Pasteur

1861

He agreed to recreate the experiment and leave the system in the open air.
Designed several bottles.
He placed a nutrient broth in one of the neck bottles, boiled the broth inside the bottle, and observed no life in bottle for a year. He broke the cap off the bottle or tipped the flask, exposing it more directly to the air and trapping particles, he noticed life forms on the brother within days. He reasoned that the contamination came from life forms in the air, not a supposed life force.