Ernst Haeckel was born in Potsdam, Germany, the son of a Prussian government official. After graduating from the cathedral gymnasium in Merseberg in 1852, he entered the University of Berlin as medical student. Haeckel took occasional semesters at the University of Würzburg to study under Franz Leydig (1821-1908), Rudolf Virchow (1821-1902), and Albert von Kölliker (1817-1905), but was particularly influenced by Johannes Müller (1801-1858) at Berlin. Never intending to become a practicing physician, he directed his efforts as much as possible toward comparative anatomy, embryology, cell biology, and marine zoology.

After receiving his medical degree in 1857, Haeckel continued his training in zoology under Müller. Only temporarily frustrated by his mentor's untimely death, he soon found a new mentor in Carl Gegenbaur (1826-1903) at the University of Jena. Named professor of zoology at Jena in 1862, he became a controversial figure, much honored...