Relevant scientists

Aristotle

1500

400 B.C. He was the first to believe in spontaneous generation.

Jean Baptiste Van Helmont

1620

He strongly believed in the theory of spontaneous generation and invented the method of making mice with dirty rags and grains. This is one of the main reasons why everybody believed in this theory.

Francesco Redi

1668

An Italian poet and physician named Francesco Redi decided to conduct an experiment against the spontaneous generation theory. Redi believed that maggots came from the eggs that were laid by flies so he put meat in various jars and sealed a few and left a few open. As he expected, only the jars that were open to air had maggots in it. This proved his theory because when the jars are sealed, flies were unable to lay eggs on the meat so there were no maggots.

Anton Van Leeuwenhoek

1674

Leeuwenhoek used his microscope to add on to Hooke’s research. He discovered bacteria and used his finding to prove how cells and bacteria generate themselves and don’t come from random nonliving things.

Lazzaro Spallanzani

1745

In the same year John Needham conducted the chicken broth experiment, an Italian clergyman was not convinced. He modified Needham’s experiment and vacuumed the air out before sealing the chicken broth and boiling it. During that experiment, no microorganisms grew. However, some believers disagreed with Spallanzani and said he simply just proved that the theory needs air to work

John Needham

1745

John Needham conducted an experiment to boil chicken broth to prove spontaneous generation. When he boiled chicken broth and put it in a sealed jar and microorganisms grew, people were more certain about the theory of spontaneous generation.

Rudolf Virchow

1855

Virchow discovered that cells only generate from other cells. This discredited the theory of spontaneous generation a lot because he proved that living things can’t come from non-living things since they don’t have cells.

Louis Pasteur

1859

A French chemist Pasteur proved the spontaneous generation theory wrong. He performed a combined experiment of Needham’s and Spallazani’s. He boiled meat in a flask and heated the neck of the flask and bent it to an S shape. This allowed air to go into the flask but does not allow air borne microorganisms because they will settle on the S. Since no microorganisms grew, Pasteur proved the spontaneous generation theory wrong and also demonstrated microorganisms are everywhere.