Theodor Schwann was a German physiologist. His many contributions to biology include
the development of cell theory, 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.
Early life Schwann was born in Neuss. His father was
a goldsmith, later a printer. Schwann studied at the Jesuits College in Cologne, and then
at Bonn, where he met physiologist Johannes Peter Müller.
Contributions It was during the four years spent under the
influence of Müller at Berlin that Schwann's most valuable work was done. Müller was at
this time preparing his great book on physiology, and Schwann assisted him in the experimental
work required. Schwann observed animal cells under the microscope, noting their different
properties. Schwann found particular interest in the nervous and muscular tissues. He discovered
the cells which envelope the nerve fibers, now called Schwann cells in his honor.
Schwann discovered the striated muscle in the upper esophagus and initiated research
into muscle contraction, since expanded upon greatly by Emil du Bois-Reymond and others.
Müller directed Schwann's attention to the process of digestion, and in 1837 Schwann
isolated an enzyme essential to digestion, which he called pepsin.
In his later years, Schwann found growing interest in theological issues. Schwann died
in Cologne on 11 January 1882. Cell theory
In 1837, Matthias Jakob Schleiden viewed and stated that new plant cells formed from the
nuclei of old plant cells. While dining that year with Schwann, the conversation turned
on the nuclei of plant and animal cells. Schwann remembered seeing similar structures in the
cells of the notochord and instantly realized the importance of connecting the two phenomena.
The resemblance was confirmed without delay by both observers, and the results soon appeared
in Schwann's famous Microscopic Investigations on the Accordance in the Structure and Growth
of Plants and Animals, in which he declared that "All living things are composed of cells
and cell products". This became cell theory or cell doctrine.
In the course of his verification of cell theory, Schwann proved the cellular origin
and development of the most highly differentiated tissues including nails, feathers, and tooth
enamel. Schwann established a basic principle of embryology by observing that the ovum is
a single cell that eventually develops into a complete organism.
Schwann's theory and observations became the foundation of modern histology. In 1857, pathologist
Rudolf Virchow posed the maxim Omnis cellula e cellula—that every cell arises from another
cell. By the 1860s, cell doctrine became the conventional view of the elementary anatomical
composition of plants and animals. Schwann's theory and observations became the foundation
of modern histology. Vitalism and germ theory
Schwann was the first of Johannes Peter Müller's pupils to break with vitalism and work towards
a physico-chemical explanation of life. Schwann also examined the question of spontaneous
generation, which led to its eventual disconfirmation. In the early 1840s, Schwann went beyond others
who had noted simply the multiplication of yeast during alcoholic fermentation, as Schwann
assigned the yeast the role of primary causal factor, and then went further and claimed
it was alive. Embattled controversy ensued as eminent chemists alleged that Schwann was
undoing scientific progress by reverting to vitalism.
After publishing anonymous mockery in a journal of their own editorship, they published a
purely physicochemical if also hypothetical explanation of the interaction resulting in
fermentation. As both the rival perspectives were hypothetical, and there was not even
an empirical definition of 'life' to hold as a reference frame, the controversy—as
well as interest itself—fell into obscurity unresolved. Pasteur began fermentation researches
in 1857 by approximately just repeating and confirming Schwann's, yet Pasteur accepted
that yeast were alive, thus dissolving the controversy over their living status, and
then Pasteur took fermentation researches further.
In retrospect, the germ theory of Pasteur, as well as its antiseptic applications by
Lister, can be traced to Schwann's influence. References
This article incorporates text from a publication now in the public domain: Chisholm, Hugh,
ed.. "Schwann, Theodor". Encyclopædia Britannica. Cambridge University Press.
Further reading Aszmann, O. C.. "The life and work of Theodore
Schwann". Journal of reconstructive microsurgery 16: 291–5. doi:10.1055/s-2000-7336. PMID 10871087.
Florkin, M.. "Episodes in medicine of the people from Liège: Schwann & the stigmatized".
Revue médicale de Liège 13: 627–38. PMID 13591909. Florkin, M.. "1838; Year of crisis in the
life of Théodore Schwann". Revue médicale de Liège 12: 503–10. PMID 13466730.
Florkin, M.. "Discovery of pepsin by Theodor Schwann". Revue médicale de Liège 12: 139–44.
PMID 13432398. Florkin, M.. "Schwann as medical student".
Revue médicale de Liège 6: 771–7. Florkin, M.. "Schwann at the Tricoronatum".
Revue médicale de Liège 6: 696–703. PMID 14883601. Florkin, M.. "The family and childhood of
Schwann". Revue médicale de Liège 6: 231–8. PMID 14845235.
Haas, L. F.. "Neurological stamp. Theodore Schwann". J. Neurol. Neurosurg. Psychiatr.
66: 103. PMC 1736145. PMID 9886465. Hayashi, M.. "Theodor Schwann and reductionism".
Kagakushi kenkyu. Journal of the history of science, Japan 31: 209–14. PMID 11639601.
Kiszely, G.. "Theodor Schwann". Orvosi hetilap 124: 959–62. PMID 6343953.
Kosinski, C. M.. "Theodor Schwann". Der Nervenarzt 75: 1248–1248. doi:10.1007/s00115-004-1805-5.
PMID 15368056. Kruta, V.. "The idea of the primary unity
of elements in the microscopic structure of animals and plants. J. E. Purkynĕ and Th.
Schwann". Folia mendeliana 22: 35–50. PMID 11621603. Lukács, D.. "Centenary of the death of Theodor
Schwann". Orvosi hetilap 123: 864–6. PMID 7043357. Watermann, R.. "Theodor Schwann accepted the
honorable appointment abroad". Medizinische Monatsschrift 27: 28–31. PMID 4576700.
Watermann, R.. "Theodor Schwann as a maker of lifesaving apparatus". Die Medizinische
Welt 50: 2682–7. PMID 13783359. External links
Short biography and bibliography in the Virtual Laboratory of the Max Planck Institute for
the History of Science Schwann, Theodor and Schleyden, M. J. 1847.
Microscopical researches into the accordance in the structure and growth of animals and
plants. London: Printed for the Sydenham Society "Theodor Schwann". Catholic Encyclopedia.
New York: Robert Appleton Company. 1913.