Spontaneous Generation

Experiments
Francesco Redi

Rotting meat was placed in two experimental jars and two control jars.
By Placing Cloth over the experimental jars of rotting meat, Redi was able to test his hypothesis that only flies can produce more flies.
Over time, the control jars were filled with maggots and flies.
However, the experimental jars were free of insects.
Demonstrates the maggots only appear if flies land on meat. (Eggs are laid)
Disproves Spontaneous Generation.

John Needham

Meath Broth is boiled for several minutes to sterilize it.
Broth is poured into two jars. One is sealed, the control, is left unsealed.
Needham hypothesis that if life arises only from life, the heated broth would stay clear, indicating no presence of living organisms.
If life can arise from non-living matter, the heated broth would become cloudy, indicating presence of living organisms.
Within days, the heated broth was cloudy.
He proclaims this as evidence in support of Spontaneous Generation.

Lazzaro Spallanzani

Lazzaro did not agree with Needham’s results.
He repeated the experiment but boiled the broth for longer.
No life appears in the sealed flask.
Disproved Spontaneous Generation Theory.
Others argued that boiling killed a vital principal contained in air. This vital principal is responsible for life arising from non-living matter.

Louis Pasteur He disproves Spontaneous Generation and concludes that living organisms do not arise from non-living matter.
He boiled the broth and no living things grew, when he tipped it, microorganisms grew
He used Swan neck flasks; they caught microorganisms and dust in the neck of the flask.
Final proof that living things come from living things.