CHAPTER XI

The Cell-Theory--Schleiden. Schwann. Schultze, 237

Unifying power of the cell-theory, 237. Vague foreshadowings, 237. The first pictures of cells from Robert Hooke's Micrographia, 238. Cells as depicted by Malpighi, Grew, and Leeuwenhoek, 239, 240. Wolff on cellular structure, 240, 241. Oken, 241. The announcement of the cell-theory in 1838-39, 242. Schleiden and Schwann co-founders, 243. Schleiden's work, 243. His acquaintance with Schwann, 243. Schwann's personal appearance, 244. Influenced by Johannes Müller, 245. The cell-theory his most important work, 246. Schleiden, his temperament and disposition, 247. Schleiden's contribution to the cell-theory, 247. Errors in his observations and conclusions, 248. Schwann's treatise, 248. Purpose of his researches, 249. Quotations from his microscopical researches, 249. Schwann's part in establishing the cell-theory more important than that of Schleiden, 250. Modification of the cell-theory, 250. Necessity of modifications, 250. The discovery of protoplasm, and its effect on the cell-theory, 250. The cell-theory becomes harmonized with the protoplasm doctrine of Max Schultze, 251. Further modifications of the cell-theory, 252. Origin of cells in tissues, 252. Structure of the nucleus, 253. Chromosomes, 254. Centrosome, 256. The principles of heredity as related to cellular studies, 257. Verworn's definition, 258. Vast importance of the cell-theory in advancing biology, 258.