University of Heidelberg physicians, Arnold at lower left.
Julius Arnold (August 19, 1835 – February 3, 1915) was a German pathologist born in Zurich. He was the son of anatomist Friedrich Arnold (1803–1890).
He studied medicine at the Universities of Heidelberg, Prague, Vienna and Berlin, where he was a student of Rudolf Virchow (1821–1902). In 1859 he became a doctor of medicine, and in 1866 he became a professor of pathological anatomy and director of the institute of pathology at Heidelberg. Arnold was the author of 120 articles in the fields of histology and pathological anatomy.
His name is lent to a disorder known as Arnold–Chiari malformation, which occurs when the cerebellar tonsils and the medulla oblongata protrude through the foramen magnum into the spinal canal. Arnold described this malformation in an infant who died shortly after delivery, and published his account in an 1894 paper titled Myelocyste, Transposition von Gewebskeimen und Sympodie. In 1891, Austrian pathologist Hans Chiari (1851–1916) also described this disorder, three years prior to Arnold's findings. In 1907, two of Dr. Arnold's students coined the eponym of "Arnold-Chiari malformation" in honor of both men.
Arnold died in 1915 in Heidelberg.