German Physician, Chemist, and Anatomist
Franciscus Sylvius was the founder of a school of medicine which proposed that all physical events of the body, including disease, are based on chemical reactions. This school of science later became known as "iatrochemistry," coming from the Greek work "iatro," which means to heal. He helped shift the perspective of medicine from mystical speculation and superstition to a rational field based on the universal laws of physics and chemistry.
The Sylvius family was of southern Flemish extraction. His grandfather, a wealthy merchant, emigrated from Cambria in France to Frankfurt-am-Main. Born in Hanau, Prussia, which is now Hanover, Germany, Franciscus Sylvius received his education at Sedan, a Calvinist academy. Because of his ancestry and residence in several countries, Sylvius is also known as Franz Deleboe or Francois Du Bois, of which Franciscus Sylvius is the Latinized version.
He went to several great universities in Europe, including Leiden, Wittenburg, and Jena, and received his doctorate at Basel, Switzerland, in 1637. He went back to Hanau to practice medicine, but soon returned to Leiden to lecture on anatomy.
At first he just lectured using the book Anatomicae intitutiones, written by Caspar Bartholin (1585-1629). Soon he found himself demonstrating dissection and anatomy to a large audience in the botanical garden of the university. Later, he devised physiology experiments for the instruction of his students. William Harvey (1604-1649) had just proposed his new theory of blood circulation, and Sylvius became an enthusiastic supporter and used dogs to demonstrate his belief in the theory. Relating physiology and chemistry, he developed a theory of the interaction between acids and bases in the blood. Also he described the nature and use of body fluids, including blood, lymph, pancreatic juice, and saliva. He was in error to assume all fluids were either acid or bases and, in order to treat disease, the correct balance must be restored.
Sylvius seemed to be limited at Leiden and in 1641 moved to Amsterdam, where he set up a profitable medical practice and became a respected member of the community. A member of the Protestant Walloon Church, he was appointed physician in charge of relief to the poor and supervisor of the Amsterdam College of Physicians. Although a dedicated physician, he did not abandon his anatomy and physiology studies and devoted spare time to his experiments. He discovered the deep cleft separating the temporal area of the brain from the frontal and parietal lobes. The cleft or fissure is named the sylvian fissure.
In 1658 representatives from Leiden persuaded Sylvius to return to accept a professorship at twice the salary offered to other professors. He threw himself into the new task and attracted students from all over Europe. He remained at Leiden from 1658-72 and became one of Europe's outstanding teachers.
He persuaded the hospital to let him try a unique innovation—taking his students with him as he went to the hospitals. He was one of the first professors to instruct future physicians as they made their rounds through the wards.
He also performed autopsies himself. His students were enthusiastic about his teachings and defended them in public debates. He published his main work, Praxeos medicae idea nova, in 1670, but did not live to see the second volume in print. He died on November 16, 1672, at Leiden.
In 1647 Sylvius married Anna de Ligne, the daughter of a lawyer, who was 13 years younger than he. She died in 1657. In 1666, he married a 22-year-old woman, who died three years later. Only one of his children grew to adulthood.
Sometimes the Dutch Sylvius is confused with Jacobus Sylvius (1478-1555) of Paris, a skilled anatomist, teacher, and later opponent of Andreas Vesalius (1514-1564).
Franciscus Sylvius was able to work with the innovations of Harvey but kept them in the general framework of Galen's humoral system. However, in his therapies, he preferred chemical medicines to those of Galen (130-200), using mercury, antimony, and zinc. In this emphasis, his work was pivotal to a new outlook of scientific investigation. He taught many students who went on to be distinguished anatomists, including Jan Swammerdam (1637-1680) and Reinier de Graaf (1641-1673).
EVELYN B. KELLY
"Franciscus Sylvius." Science and Its Times: Understanding the Social Significance of Scientific Discovery. . Encyclopedia.com. (March 18, 2019). https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/franciscus-sylvius
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