Nov 05, 2007 · 1833 – Brown descibed the cell nucleus in cells of the orchid. 1838 – Schleiden and Schwann proposed cell theory. 1840 – Albrecht von Roelliker realized that sperm cells and egg cells are also cells. 1856 – N. Pringsheim observed how a sperm cell penetrated an egg cell.
Nov 11, 2019 · Development of Cell Theory 1840 Albrecht von Roelliker stated that sperm and egg are composed of cells and that all humans are configured from cells. 1849 Louis Pasteur was developing fermentation, a process to kill bacteria, he proved that bacteria are able to multiply and that bacterial cells come from other bacterial cells.