born July 26, 1815, Posen, Prussia died Aug. 29, 1865, Kissingen, Bavaria German embryologist and neurologist. He discovered and named the three germ layers of cells that develop in the early embryo: the ectoderm, mesoderm, and endoderm. He also discovered Remak fibres (nerve fibres with no myelin sheath) and Remak ganglia (neurons in the heart) and was a pioneer in electrotherapy for nervous diseases. He achieved enough eminence to obtain a lectureship at the University of Berlin despite Prussian laws barring Jews from teaching