German Neurofisico. He was born in Posen, and died in Kissingen. He studied medicine in Berlin with the anatomist and physiologist Johannes Müller. In 1838 he wrote his doctoral thesis on the microscopic structure of the nervous system. He was Assistant, for four years, from Johann Lucas Schönlein. In 1847, he obtained a Chair as first medical Jew in Prussia. In Berlin he was appointed Professor at the University in 1859.
He discovered the covering of myelin that surrounds the main nerves, noting that the cilindroeje, axon, born in the spinal cord and extends inside the body without discontinuity. It confirmed the presence of a solid structure and flattened in the nerves, (until then it was believed that nerves were hollow and structure). Was the precursor of embryology and one of the first scientists who discovered in detail cell division, stating that animal cells come from other cells already in existence. He was the first to use electricity as a treatment in some diseases.