Science WebQuests

     Born in Hamburg and educated in law at Heidelberg, Schleiden left law practice to study botany, which he then taught at the University of Jena from 1839 to 1862. A man who liked to start heated arguments, he scorned the botanists of his day who limited themselves to merely naming and describing plants. Schleiden investigated plants on a microscopic level and conceived that plants were made up of recongnizable units, or cells.

   

   Schleiden concluded that all plant tissues are composed of cells and that young plants arise from a single cell.  He declared that the cell is the basic building block of all plant matter. This statement of Schleiden was the first generalizations concerning cells.  He also forecasted that plant growth takes place by the generation of new cells somehow involving the nucleus. Although his idea of how cell division took place was not correct, he was definitely on the right track!

​

     In 1837, he stated that plant growth came about through the production of new cells and that new offspring came from the nuclei of old cells.  While he was correct about the production of new cells, later discoveries proved that his theory of the role of the nucleus in mitosis was incorrect.  His ideas of the cell as the common structural unit of plants had the profound effect of shifting scientific attention to living processes as they happened on the cellular level-a change that initiated the field of embryology. A year after Schleiden published his cell theory on plants, his friend Schwann extended it to animals, thereby bringing botany and zoology together under one unifying theory.