What helped Schwann to formulate the cellular theory of the structure of organisms. Why did this theory play a huge role in biology?

The prerequisites for the creation of cell theory were the invention and improvement of the microscope and the discovery of cells (R. Hooke). The works of M. Malpigi, N. Grue, A. Van Levenguk – allowed to see the cells of plant organisms. R. Brown described the nucleus of a plant cell. Ya. E. Purkine introduced the concept of protoplasm. M. Schleiden proved that every cell has a nucleus.
The cell theory allowed us to conclude that the chemical composition of all cells is similar, the general plan of their structure, which confirms the phylogenetic unity of the whole living world.

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