(1)1838-1839, Schleiden, a German botanist, and Wang Shi, a German zoologist, put forward the cell theory, the basic contents of which are as follows:
① Cells are organisms, and all animals and plants are developed from cells and consist of cells and cell products.
As a relatively independent unit, each cell not only has its own life, but also contributes to the whole life composed of other cells.
(3) New cells can be produced by the reproduction of existing cells.
(2) In1858, Wei Xiaoer made an important supplement to the cell theory, emphasizing that cells can only come from cells. Cell theory is of great significance to the development of biological science. Cell theory, evolution theory and Mendelian genetics are called the three cornerstones of modern biology, and cell theory is the cornerstone of the latter two. Understanding the structure and function of cells is essential for the further development of biology, medicine and its branches.