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Redi, Francesco


(b. Arezzo, Italy, 18 February 1626; d. Pisa, Italy. 1 March 1697 or 1698)

entomology, parasitology, toxicology.

Redi was the son of Gregorio Redi, a renowned Florentine physician who also worked at the Medici court, and Cecilia de’ Ghinci. He graduated in philosophy and medicine from the University of Pisa on 1 May 1647. On 26 April 1648 he registered at the Collegio Medico in Florence. He served at the Medici court as head physician and superintendent of the ducal pharmacy and foundry. Friend, counselor, and virtual secretary to his employers, he was also a member of the small Accademia del Cimento, which flourished actively, although intermittently, at the Medici court from 1657 to 1667. This decade at the Academy coincided with the period in which Redi produced his most important works.

In 1664 there appeared the Osservazioni intorno alle vipere, which was closely related to the doctrine of the circulation of the blood. Redi was by then superintendent of the ducal pharmacy, where snakes were widely used in the preparation of theriaca. Contrary to prevailing belief, Redi held that snake venom was completely unrelated to its bile. It was rather the yellow humor produced by “two glands, which I have found in all vipers.” The humor stagnates in the “two sheaths in which the viper conceals its fangs” and, “when the viper bares its fangs and strikes, it is of necessity spurted on the wound” He also exonerated the viper’s animal spirits, which had been considered responsible for the effects of the bite inflicted by the enraged and vindictive serpent.

Sucking the tissues bitten by the viper was harmless, Redi discovered, since the poison was ineffective if swallowed: to be effective it had to be inoculated into the animal’s tissues and enter the bloodstream. Hence he considered it advantageous to make “a tight ligature not far above the wound so that the poison is not carried to the heart by the circular movement of the blood and all the blood infected.”

To achieve these results, which mark the first stirrings of experimental toxicology, Redi performed countless experiments on the effects of snakebite. With the venom obtained from living as well as dead snakes, he poisoned other animals. He either sprinkled liquid or powdered venom on wounds, or inserted into the flesh “sharp slivers of broom” soaked with the poison. The animal was not rendered poisonous to eat; and Redi examined the viscera in vain in an attempt to discover the mechanism of action of the fatal toxin.

Redi’s masterpiece is considered to be Esperienze intorno alia generazione degli insetti (1668), in which he disproved the doctrine of spontaneous generation in insects, inherited from Aristotle and still considered dogma. The microscope revealed in insects an organization as marvelous as it was unsuspected. Redi prepared and observed the egg-producing apparatus in insects, and he also used the microscope to good advantage in observing the morphological elements characteristic of the eggs of each species.

Redi then set out to attack the doctrine of spontaneous generation in the lower animals. Even if decaying animals or plants appeared to “give birth to an infinity of worms [larvae]” the reality was quite different, he held. It must be assumed “that flesh and plants and other things whether putrefied or putrefiable play no other part, nor have any other function in the generation of insects, than to prepare a suitable place or nest into which, at the time of procreation, the worms or eggs or other seed of worms are brought and hatched by the animals; and in this nest the worms, as soon as they are born, find sufficient food on which to nourish themselves excellently.” These organic bodies “never become verminous if they are kept in a place where flies and gnats cannot enter.” Redi demonstrated this in experiments of almost unique simplicity, using wide-mouthed flasks containing such organic substances as meat or cheese.

Contagion by insects was therefore necessary before decaying substances could develop worms. Redi supposed it was necessary in living plants and animals as well—the worms and insects found in fruit, in the galls of plants, and inside the bodies of animals, for instance, the liver fluke (Fasciola hepatica and the larva of the gadfly. After proposing these highly significant examples of entozoa, Redi ended Esperienze with a long review of ectozoa. observed in various animals, which he also felt “more inclined to believe … are born from the eggs laid by their mothers, fertilized by coitus,” Despite Redi’s research, the question remained open. Led astray by various observations—especially by the “many fibers and threads” that from the wall of the “gall run to the egg, almost like so many veins and arteries which convey the material suitable for formation of the egg and worm and for the nutriment of which they have need” —Redi confined himself, provisionally, to attributing a zoogenic property to vegetable organisms and even to living animals. The insects in galls were, like those in the cherry, “generated by the same spirit and the same natural power that give birth to the fruits of plants.” It was left to Malpighi (1679) to deny spontaneous generation also for the insects of galls.

Redi’s major parasitological treatise, Ossenazioni intorno agli animali viventi. che si trovano negli animali viventi (1684), was an abundant compilation of endo-parasitic helminths found in the organs of different classes of animals, including mollusks and crustaceans. Jules Guiart, who in 1898 attempted to identify the parasites described by Redi, compiled a list of 108 items, two-thirds of which were endoparasitic helminths, and one-third cctoparasitic insects and acarids. In the 1684 Ossenazioni Redi also formulated the idea of an evolutionary cycle of parasitic worms.

Redi’s studies on the generation of insects and on parasitism, which culminated in the acarian etiology of scabies, were extended by the physician Giovanni Cosimo Bonomo and the apothecary Giacinto Cestoni. Their results were presented in a full and concise formulation that had been subjected to Redi’s corrections and embellishments: the Osservazioni intorno a’ pellicelli del corpo umano (1687).

Like Galileo, Redi used the Italian language with mastery, both in his scientific works and in the “consultations” he composed as a practicing physician. His great knowledge of his mother tongue, including rare and obsolete terms, was a great help in his contributions to a revision of the dictionary of the Accademia della Crusca. But his literary contributions, unlike his scientific, were marked by fabrications; and he took pleasure in defending the correctness of terms he had invented himself. Even the history of science was not spared by these fabrications, since his apocryphal version of the invention of spectacles was accepted for over two centuries.


I. Original Works. Redi’s works include Osservazioni intorno alle vipere serine in una lettera a Lorenzo Magalotti (Florence, 1664); Esperienze intorno alia generazione degli insetii scritte in una lettera a Carlo Dati (Florence, 1668); Lettera sopra aleune opposizioni fatte alle sue Osservazioni intorno alle vipere seritta alii Ab. Bourdelot Sig. di Conde e S. Leger e Alessandro Moro (Florence, 1670); Esperienze intorno a diverse eose naturali, e particolarmente a quelle che ei sono portate dairindie, seritte in una lettera al P. Atattasio Chircher (Florence, 1671); Lettera intorno all’in-venzione degli occhiali seritta a Paolo Faconieri (Florence, 1678); Osservazioni intorno agli animali viventi che si trovano negli animali viventi (Florence, 1684).

For other editions, works, and collections of works, see Dino Prandi, Bibliografia delle opere di Francesco Redi (Reggio Emilia, 1941).

II. Secondary Literature. On Redi and his work, see Luigi Belloni, “Francesco Redi, biologo,” in Celebrazione del’ Aceadetnia del Cimento nel tricentenariodella fondazione(Domus Gatilacana, 1957) (Pisa, 1958), 53–70; “Francesco Redi als Vertreter der italienischen Biologie des XVII. Jahrhunderts,” in Munchener Medizinische Wochenschrift, 101 (1959), 1617–1624; and “L’influence exercée sur la médecine clinique par les sciences de base développées par l’école Galiléienne (génération spontanée et ‘contagium vivunV dc la Gate),” in Clio medica, 8 (1973), 143–149; Andrea Corsini, “Sulla vita di Francesco Redi. Nuovo contributo di notizie,” in Riviista di storia critica delle scienze mediehe e naturali, 13 (1922), 86–93; Jules Guiart, “Francesco Redi,” in Archives de parasitologie,1 (1898), 420–441; Dino Prandi, Bibliografia delle opere di Francesco Redi (Reggio Emilia, 1941); Ugo Viviani, Vita ed opere inedite di Francesco Redi, 3 vols. (Arezzo, 1928–1931); and “L’autopsia e la data della morte di Francesco Redi,” in Archeion, 16 (1934), 181–185; and Nella Volterra, “Sulla malattia e suila morte di Francesco Redi,” ibid., 15 (1933), 73–77.

A further bibliography on Redi is contained in Viviani (I, 103–117) and in Prandi (pp. v-vi).

On Redi’s literary falsifications and their influence on the history of the invention of spectacles, see Giuseppe Albertotti, “Note critiche e bibliografiche riguardanti la storia degli occhiali,” in Annali di ottalmologia e clinica oculistica, 43 (1914), 328–356; and “Lettera intorno alia invenzione degli occhiali scritta da Giuseppe Albertotti Senatore Isidoro del Lungo,” ibid., 50 (1922), 85–104; Isidoro del Lungo, “Le vicende d’un’im-postura erudita (Salvino degli Armati),” in Archivio storico italiano, 78 (1920), 5–53; and Chi l’inventore degli occhiali? (Bologna, 1921); and Guglielmo Volpi, “Lc falsificazioni di Francesco Redi nel vocabolario dclla Crusea,” In Atti della R. Accademia dclla Crusca (1915–1916), 33–136.

Luigi Belloni

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"Redi, Francesco." Complete Dictionary of Scientific Biography. . 29 Apr. 2017 <>.

"Redi, Francesco." Complete Dictionary of Scientific Biography. . (April 29, 2017).

"Redi, Francesco." Complete Dictionary of Scientific Biography. . Retrieved April 29, 2017 from

Redi, Francesco

Francesco Redi (fränchās´kō rā´dē), 1626?–1698?, Italian naturalist, poet, philologist, and court physician to the dukes of Tuscany. Through controlled experiments he demonstrated that certain living organisms, notably maggots in rotting meat, did not arise, as had been alleged, through spontaneous generation. His Generation of Insects (1668, tr. 1909) is included in the nine-octavo edition (1809–11) of his complete writings. His chief poetical work was the dithyrambic ode Bacchus in Tuscany (1685; tr. by Leigh Hunt 1825).

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"Redi, Francesco." The Columbia Encyclopedia, 6th ed.. . 29 Apr. 2017 <>.

"Redi, Francesco." The Columbia Encyclopedia, 6th ed.. . (April 29, 2017).

"Redi, Francesco." The Columbia Encyclopedia, 6th ed.. . Retrieved April 29, 2017 from