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.