Francesco-redi-11-25.docx

Dante Q. Dela Cruz Jr.

SCI-14

MWF 1:30

November 25, 2016

BSA-III

“Francesco Redi: His life and Experiment to test the Theory of Spontaneous Generation” Francesco Redi (18 February 1626 – 1 March 1697) was an Italian physician, naturalist, biologist and poet. He is referred to as the "founder of experimental biology", and as the "father of modern parasitology". He was the first person to challenge the theory of spontaneous generation by demonstrating that maggots come from the eggs of flies. Having a doctoral degree and in both medicine and philosophy from the University of Pisa at the age of 21, he worked in various cities of Italy. A rationalist of his time, he was a critic of verifiable myths, such as spontaneous generation. His most famous experiments are described in his magnum opus Esperienze Intorno alla Generazione degl'Insetti (Experiments on the Generation of Insects), published in 1668. He disproved that vipers drink wine and could break glasses, and that their venom was poisonous when ingested. He correctly observed that snake venoms were produced from the fangs, not the gallbladder, as was believed. He was also the first to recognize and correctly describe details of about 180 parasites, including Fasciola hepatica and Ascaris lumbricoides. He also distinguished earthworms from helminths (like tapeworms, flukes, and roundworms). He possibly originated the use of the control method, the basis of experimental design in modern biology. A posthumous collection of his poems Bacco in Toscana ("Bacchus in Tuscany") is considered among the finest works of the 17th-century Italian poetry. Redi is best known for his series of experiments, published in 1668 as Esperienze Intorno alla Generazione degli Insetti (Experiments on the Generation of Insects), which is regarded as his masterpiece and a milestone in the history of modern science. The book is one of the first steps in refuting "spontaneous generation"—a theory also known as Aristotelian abiogenesis. At the time, prevailing wisdom was that maggots arose spontaneously from rotting meat.

Redi's experiment on abiogenesis Redi took six jars and divided them into two groups of three: In one experiment, in the first jar of each group, he put an unknown object; in the second, a dead fish; in the last, a raw chunk of veal. Redi covered the tops of the first group of jars with fine gauze so that only air could get into it. He left the other group open. After several days, he saw maggots appear on the objects in the open jars, on which flies had been able to land, but not in the gauze-covered jars. In the second experiment, meat was kept in three jars. One of the jars was uncovered, and two of the jars were covered, one with cork and the other one with gauze. Flies could only enter the uncovered jar, and in this, maggots appeared. In the jar that was covered with gauze, maggots appeared on the gauze but did not survive He continued his experiments by capturing the maggots and waiting for them to metamorphose, which they did, becoming flies. Also, when dead flies or maggots were put in sealed jars with dead animals or veal, no maggots appeared, but when the same thing was done with living flies, maggots did. Knowing full well the terrible fates of out-spoken thinkers such as Giordano Bruno and Galileo Galilei, Redi was careful to express his new views in a manner that would not contradict theological tradition of the Church; hence, his interpretations were always based on biblical passages, such as his famous adage: omne vivum ex vivo ("All life comes from life").

Redi’s Scientific Method: Observation: When there is raw meat, there are maggots. Statement of the problem: Why do maggots suddenly appear on raw meat? Is it Spontaneous generation? Hypothesis: Flies produce maggots Experiment: Controlled variables: jars, type of meat, temperature, and time. Manipulated variables: gauze covering that kept flies away from the meat. Responding variables: whether maggots appeared on the meat. Analysis of the Data: Redi kept his findings and observations in a scientific journal which showed that maggots only appeared on the meat in jars that were NOT covered with gauze. Conclusion: He used evidence from his experiment that supported his hypothesis: flies produce maggots.