AP BIOLOGY

Detailed explanation-1: -Schleiden argued that cells form around nuclei, with cell membranes growing out of nuclear structures. Schwann, meanwhile, thought that animal cells tended to “crystallize” out of the material between previously existing cells, which he called the cytoblastema.

Detailed explanation-2: -The classical cell theory was proposed by Theodor Schwann in 1839. There are three parts to this theory. The first part states that all organisms are made of cells.

Detailed explanation-3: -Credit for developing cell theory is usually given to three scientists: Theodor Schwann, Matthias Jakob Schleiden, and Rudolf Virchow. In 1839, Schwann and Schleiden suggested that cells were the basic unit of life. Their theory accepted the first two tenets of modern cell theory (see next section, below).

Detailed explanation-4: -Four of them stand out: Charles Robin, Aristide Verneuil, Paul Broca, and Eugène Follin. In the 1850s, they formed the core group of this micrographic school, and for a long time-with the notable exception of Robin-they were the first proponents of the idea of the cancer cell. All of them firmly opposed cell theory.