a reminder to myself about thinking

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In 1668, Francesco Redi, an Italian physician, did an experiment with flies and wide-mouth jars containing meat. This was a true scientific experiment — many people say this was the first real experiment — containing the following elements

-Observation: There are flies around meat carcasses at the butcher shop.

-Question: Where do the flies come from? Does rotting meat turn into or produce the flies?

-Hypothesis: Rotten meat does not turn into flies. Only flies can make more flies.

-Prediction: If meat cannot turn into flies, rotting meat in a sealed (fly-proof) container should not produce flies or maggots.

-Testing: Wide-mouth jars each containing a piece of meat were subjected to several variations of “openness” while all other variables were kept the same.
control group — These jars of meat were set out without lids so the meat would be exposed to whatever it might be in the butcher shop.
experimental group(s) — One group of jars were sealed with lids, and another group of jars had gauze placed over them.
replication — Several jars were included in each group.

-Data: Presence or absence of flies and maggots observed in each jar was recorded. In the control group of jars, flies were seen entering the jars. Later, maggots, then more flies were seen on the meat. In the gauze-covered jars, no flies were seen in the jars, but were observed around and on the gauze, and later a few maggots were seen on the meat. In the sealed jars, no maggots or flies were ever seen on the meat.

-Conclusion(s): Only flies can make more flies. In the uncovered jars, flies entered and laid eggs on the meat. Maggots hatched from these eggs and grew into more adult flies. Adult flies laid eggs on the gauze on the gauze-covered jars. These eggs or the maggots from them dropped through the gauze onto the meat. In the sealed jars, no flies, maggots, nor eggs could enter, thus none were seen in those jars. Maggots arose only where flies were able to lay eggs. This experiment disproved the idea of spontaneous generation for larger organisms.