Born near Dusseldorf, Germany, Schwann attended the University of Bonn, then did post-graduate work under Johannes Muller at the University of Wurzburg and the University of Berlin. He later took a position as the Chair of Anatomy at the University of Louvain, Belgium, moving later to the University of Liege. He never married. Schwann was described as a gentle man who led a simple life and avoided controversy. Schwann's foremost contribution to biology was the generalized cell theory he published in 1839, when he was 29, which showed that animals, like plants, are made entirely of cells. Although Matthias Schleiden had published his findings on plant cell structure earlier, Schwann's work was more comprehensive. Having discussed Schleiden's work over dinner together in October 1838, Schwann said it sounded similar to what he had been seeing in animal cells. After dinner the two went to Schwann's lab and discovered that the cell structure in a dorsal cord was almost the same as that of plants. Schwann concluded that a cell structure was common to all living organic matter, a conclusion that united animal and vegetable biology as one science.
Schleiden and Schwann's cell theory was incomplete in many ways. It was also incorrect. It was incomplete in that it only focused on the cell structure, but didn't explore in great detail the cell contents, nor the chemical processes--dubbed "metabolism" by Schwann--carried out inside the cells.
It was incorrect primarily in terms of cell development. Schwann wholeheartedly accepted Schleiden's assertion that cells were created by a process of crystalization, starting with a nucleus (which Schleiden called a "cytoblast") which gradually grew a protective wall around itself. Once cell formation was complete, they believed, the nucleus would dissolve, leaving a. fluid interior. That theory, of course, was later disproved and replaced with the understanding we have today of cell division. After this work Schwann did not contribute much to the further development of cytology. Schwann's other primary contribution to the world of biology was his work on fermentation. As early as 1680, Leeuwenhoek had seen "crystals" forming in the process of fermentation. Schwann proved that those crystals were in fact living organisms. Most chemists at the time were convinced that alcoholic fermentation was a result of chemical instability. Through a series of controlled experiments, Schwann found that alcoholic fermentation seemed to be dependent on the presence of living organisms (yeasts) in the surrounding air. Other chemists were not quick to accept his conclusions until 1857, when the French chemist Louis Pasteur confirmed and expanded on Schwann's earlier work.
This is the complete article, containing 424 words
(approx. 1 page at 300 words per page).
