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Summary Article: Spallanzani, Lazzaro (1729-1799)
From The Hutchinson Dictionary of Scientific Biography

Place: Italy

Subject: biography, biology

Italian physiologist who is famous for disproving the theory of spontaneous generation. In his later years Spallanzani became widely renowned for his biological investigations and received many academic honours, including a fellowship of the Royal Society of London in 1768.

Spallanzani was born on 12 January 1729, the son of a distinguished lawyer. He attended the local school until he was 15, when he went to the Jesuit college at Reggio. He was invited to join the Jesuit order, but declined. He then studied law at the University of Bologna where, under the influence of his cousin Laura Bassi, who was professor of physics and mathematics there, Spallanzani became interested in science and broadened his education to include mathematics, chemistry, natural history, and French. In 1754, after obtaining his doctorate, he was appointed professor of logic, metaphysics, and Greek at Reggio College. Three years later he was ordained a priest, but performed his priestly duties irregularly and devoted himself almost entirely to his scientific studies - which were greatly facilitated by the moral protection and financial assistance provided by the church. Spallanzani was professor of physics at Modena University 1760-69, when he became professor of natural history at the University of Pavia, a position he held for the rest of his life. In his later years Spallanzani travelled widely in order to further his scientific investigations. He died in Pavia on 11 February 1799.

Spallanzani is best known for finally disproving the theory of spontaneous generation. The experiments of Francesco Redi (1626-1697) on fly maggots in 1668 proved that complex animals do not arise spontaneously, but until Spallanzani's investigations, it was still generally believed that simple life forms were generated spontaneously from rotting food. After performing hundreds of experiments in which he boiled infusions of vegetable matter in hermetically sealed flasks and found that no micro-organisms had grown in the broth, Spallanzani was able to report in 1765 that this was not the case.

Spallanzani also investigated many other biological problems, such as the physiology of blood circulation. In 1771, while examining the vascular network in a chick embryo, he discovered the existence of vascular connections between arteries and veins - the first time this connection had been observed in a warm-blooded animal. He also studied the effects of growth on the circulation in chick embryos and tadpoles; the influence of gravity and the effects of wounds on various parts of the vascular system; and changes that occur in the circulation of dying animals. In addition, Spallanzani showed that the arterial pulse is caused by sideways pressure on the expansile artery walls from heartbeats transmitted by the bloodstream.

Spallanzani also studied digestion and, after administering food samples in perforated containers to a wide variety of animals and then recovering the containers and examining them, concluded that the fundamental factor in digestion is the solvent property of gastric juice - a term first used by him. In his investigations of reproduction, he showed that the clasp reflex in amphibians persists after the male has been severely mutilated or even decapitated. (The clasp reflex is an automatic action on the part of the male in which he tightly holds the female during mating.) And in 1765 he performed an artificial insemination of a dog. Spallanzani's other biological investigations included the resuscitation of rotifers; the regeneration of decapitated snails' heads; the migration of swallows and eels; the flight of bats; and the electric discharge of torpedo fish (electric rays). In his later years Spallanzani studied respiration, proving that tissues use oxygen and give off carbon dioxide.

In addition to his biological work, Spallanzani also studied various problems in physics, chemistry, geology, and meteorology, as well as pioneering the science of vulcanology.

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