page_title: Theodor Schwann
section_title: Career
hierarchical_section_title: Theodor Schwann / Career
caption_attribution_description: English: Bronze statue of Theodor Schwann (1810-1882), founder of the cell theory for all living organisms (1839), Institute of Zoology, Liege, Belgium.
context_page_description: Theodor Schwann was a German physician and physiologist. His most significant contribution to biology is considered to be the extension of cell theory to animals. Other contributions include the discovery of Schwann cells in the peripheral nervous system, the discovery and study of pepsin, the discovery of the organic nature of yeast, and the invention of the term metabolism.
context_section_description: From 1834-1839, Schwann worked as an assistant to Müller in at the Anatomisch-zootomische Museum at the University of Berlin. Schwann carried out a series of microscopic and physiological experiments focused on studying the structure and function of nerves, muscles and blood vessels. In addition to performing experiments in preparation for Müller's book on physiology, Schwann did research of his own. Many of his important contributions were made during the time that he worked with Müller in Berlin.
  Schwann used newly powerful microscopes to examine animal tissues.  This enabled him to observe animal cells and note their different properties. His work complemented that of Matthias Jakob Schleiden in plants and was informed by it; the two were close friends.
  Described as quiet and serious, Schwann was particularly gifted in the construction and use of apparatus for his experiments. He was also able to identify important scientific questions and design experiments to systematically test them.  His writing has been described as accessible, and his logic as a "clear progression". He identified the question that he wanted to answer and communicated the importance of his findings effectively to others. His co-worker Jakob Henle spoke of him as having an "inborn drive" to experiment.
  By 1838, Schwann needed a position with a more substantial salary.  He hoped to return to Bonn, a Catholic city.  He attempted to gain a professorship there in 1838 and again in 1846, but was disappointed. Instead, in 1839, Schwann accepted the chair of anatomy at the Université Catholique de Louvain in Leuven, Belgium, another Catholic city.
  Schwann proved to be a dedicated and conscientious professor.
  With his new teaching duties, he had less time for new scientific work.  He spent considerable time perfecting experimental techniques and instruments for use in experiments. He produced few papers. One exception was a paper in 1844 that reported on a series of experiments on dogs and established the importance of bile in digestion.
  In examining processes such as muscle contraction, fermentation, digestion, and putrefaction, Schwann sought to show that living phenomena were the result of physical causes rather than "some immaterial vital force". Nonetheless, he still sought to reconcile "an organic nature" with  "a divine plan." Some writers have suggested that Schwann's move in 1838, and  his decreased scientific productivity after that, reflect religious concerns and perhaps even a crisis relating to the theoretical implications of his work on cell theory. However, other authors regard this as misrepresenting his thinking, and reject the idea that Schwann went through an existential crisis or a mystical phase. Ohad Parnes uses Schwann's laboratory notebooks and other unpublished sources along with his publications to reconstruct his research as a unified progression. Florence Vienne draws on unpublished writings to discuss the ways in which cell theory, as a "unifying principle of organic development", related to the philosophical, religious, and political ideas of various proponents including Schwann.
  In 1848, Schwann's compatriot Antoine Frédéric Spring convinced him to transfer to the University of Liège, also in Belgium. At Liège, Schwann continued to follow the latest advances in anatomy and physiology but did not himself make major new discoveries. He became something of an inventor.  One of his projects was a portable respirator, designed as a closed system  to support human life in environments where the surroundings  cannot be breathed.
  By 1858 he was serving as professor of physiology, general anatomy and embryology. As of 1872, he ceased to teach general anatomy, and as of 1877, embryology. 
  He retired fully in 1879.
  Schwann was deeply respected by his peers.  In 1878, a festival was held to celebrate his years of teaching and his many contributions. He was presented with a unique gift: a book containing 263 autographed photographic portraits of scientists from various countries, each of them sent by the scientist to be part of the gift 
caption: Bronze statue of Theodor Schwann at the entrance of the Institute of Zoology, University of Liege, Belgium
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