Redi: meat in sealed and open flasks (Esperienze intorno alla generazione degl'insetti)
A controlled experiment against spontaneous generation of animals from rotting meat. In 1668 the Italian physician Francesco Redi placed a snake, fish, eels and veal in vessels, some of which he sealed with paper and twine and some left open: maggots appeared only where flies had access.
The refutation is partial: Redi himself kept his belief that trees generate wasps and gallflies (galls). This error is usually held against him (Bernardi); Parke (2014) disputes that Redi here departed from his own rigour.
Why this date
high
Other links
-
The doctrine of spontaneous generation in Aristotle's "Generation of Animals"
refuted by · Confidence: high
Redi's experiments with meat in sealed flasks are regarded as a key contribution to the downfall of belief in spontaneous generation, although Redi himself retained it for gall wasps.
Dispute: The refutation is partial. Parke (2014) shows that Redi did not reject spontaneous generation as such: for galls he accepted it, and this was not a "mistake" but a consistent position within his system. Textbooks present Redi as a complete refutation; historians disagree.
Link sources
- Parke 2014, abstract (2014) Verified 20 Sep 2026
Francesco Redi's seventeenth-century experiments on insect generation are regarded as a key contribution to the downfall of belief in spontaneous generation. Scholars praise Redi for his experiments demonstrating that meat does not generate insects, but condemn him for his claim elsewhere that trees can generate wasps and gallflies.
- Redi 1668, Parke 2014 (2014) Verified 20 Sep 2026, quotation assembled from fragments
I placed in four wide-mouthed flasks a snake, some freshwater fish, four eels from the Arno and a piece of milk-fed veal; then, having closed the openings with paper and twine and sealed them well, I put the same materials in four other flasks and left their mouths open: before long the fish and the meat in the latter flasks became maggoty...but in the sealed flasks I never saw a single maggot born.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong. "Assembled from fragments" means the words do not stand together on the page: we found each fragment separately and joined them with an ellipsis.
- Parke 2014, abstract (2014) Verified 20 Sep 2026
Node sources
- Parke E.C. Flies from meat and wasps from trees. Stud. Hist. Phil. Biol. Biomed. Sci. 45: 34-42 (2014) Verified 5 Oct 2026
in the middle of July I placed in four wide-mouthed flasks a snake, some freshwater fish, four eels from the Arno and a piece of milk-fed veal; then, having closed the openings with paper and twine and sealed them well, I put the same materials in four other flasks and left their mouths open: before long the fish and the meat in the latter flasks became maggoty
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
Further reading
Not evidence: these carry no quotation and support nothing we wrote. They are books and scans to read next.