theodor schwann (1810 - 1882)
Theodor Schwann was a German cytologist, histologist and physiologist, author of the cell theory.
Schwann's most significant contribution to biology is considered to be the extension of cell theory to animals. Schwann extended Schleiden's theory of the cell as the basic unit of the plant world to animals. In 1839 Schwann published his seminal work on the general theory of the cell as the basis of life, Mikroskopische Untersuchungen ber die Uebereinstimmung in der Struktur und dem Wachsthum der Thiere und Pflanzen ("Microscopic Investigations on the correspondence in the structure and growth of animals and plants"). Schwann's theory can thus be regarded as the progenitor of the school of mechanistic materialism in biology.
Schwann also studied the formation of yeast spores and concluded that the fermentation of sugar and starch was the result of life processes. He also introduced the term metabolism to describe the chemical changes that occur in living tissues, defined the role of microorganisms in putrefaction, and formulated the basic principles of embryology, noting that an egg is a single cell that eventually develops into a complete organism.
