Evolution of the cell theory.

The problem of the nature of life has a long history going back to the Greeks. There was little real progress until the 19th century and Aristotle may have been at home with many 18th century ideas about vital forces and basic units. Although Hooke described cells in 1665 it took a further 200 years for the significance and nature of cells to be appreciated. In the mid 18th century some considered the basic building blocks of living matter to be fibrous. Globular theories, the precursor to the cell theory, were quite popular at the beginning of the 19th century. Many workers, as microscopes improved, had described various cell types and structures including the nucleus but the idea that cells were the universal units is associated with in 1838 and that of Schwann in 1839. However, Schwann mistakenly thought that cells could form de novo. Cell division was established by Remak and others in the 1850s. Mitosis was first understood by Flemming in 1882. The existence of the animal cell membrane was only established by the beautiful experiments of Overton in 1895. The history of the cell theory can be used to show that progress can be based on incorrect but productive ideas. It is one of the most important ideas in all of biology.