Experiments

Redi's Experiment

1668

In 1668, Italian scientist Francesco Redi conducted an experiment to challenge the idea of spontaneous generation. He placed meat in three sets of jars: one open to the air, one covered, and one sealed. Maggots only appeared in the open jars where flies could lay eggs on the meat, refuting the notion that living organisms could arise spontaneously from non-living matter. This experiment was a pivotal step in discrediting the spontaneous generation hypothesis.

Needham Rebuttal

1745

Needham argued for spontaneous generation in the 18th century, attributing microorganism appearance in sealed flasks to a "vital force" and invisible contaminants. However, subsequent experiments by Spallanzani and Pasteur refuted this, showing that life did not spontaneously generate under controlled conditions.

Criticism from Spallanzani

1858

Spallanzani critiqued Needham's spontaneous generation experiments in the 18th century. His sealed flask experiments, emphasizing extended boiling and microscopic examination, contradicted Needham's results. Spallanzani argued that Needham's sealing technique allowed contamination, supporting the rejection of spontaneous generation in favor of biogenesis.

Pasteur puts spontaneous generation to rest

1862

Pasteur's swan-neck flask experiment disproved spontaneous generation by showing that sterile broth exposed to air remained free of microorganisms. This affirmed the principle of biogenesis, stating that life comes from pre-existing life.