Matthias Schleiden

Matthias Schleiden was a German botanist who, together with the physiologist Theodor Schwann, formulated cell theory in the late 1830s, one of the foundational unifying concepts of modern biology. Schleiden's own 1838 study of plant tissue proposed that the cell is the basic structural unit from which all plant tissues are built, based on his microscopic observations that plant tissue is composed of distinct individual cells, and he emphasized the central role of the cell nucleus, recently described by botanist Robert Brown, in the process by which new cells form. When Schwann extended this cellular framework to animal tissue shortly afterward, the two scientists' combined work established that all living organisms, plant and animal alike, are built from the same basic unit, the cell, a principle that became one of the central tenets of biology. Schleiden was also known during his lifetime as an outspoken advocate for applying rigorous, exact scientific methods, including the use of the microscope, to botany, at a time when much of the field remained largely descriptive and classificatory.