  theodor schwann (7 december 1810 â 11 january 1882) 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 mÃ¼ller. ==contributions== it was during the four years spent under the influence of mÃ¼ller at berlin that schwann's most valuable work was done. mÃ¼ller 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. mÃ¼ller 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 (as had been shown by mÃ¼ller) 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 ac
1810_births 1882_deaths Foreign_Members_of_the_Royal_Society German_Roman_Catholics German_biologists Humboldt_University_of_Berlin_alumni Members_of_the_Royal_Swedish_Academy_of_Sciences People_from_Neuss People_from_the_Rhine_Province Physiologists Recipients_of_the_Copley_Medal University_of_Bonn_alumni University_of_LiA"ge University_of_WA 1/4 rzburg_alumni UniversitA(c)_catholique_de_Louvain