Simplify the following text for a Grade 9 native English-speaking person.
Original: Theodor Heinrich Boveri ( 12 October 1862 â `` 15 October 1915 ) was a German biologist who made discoveries in cytology , embryology and genetics .
Simplified: Theodor Heinrich Boveri ( 12 October 1862 â `` 15 October 1915 ) was a German biologist .