Complex sentence: He retained his post at USNM until 1912 and taught physiology (1903--1904 and 1907--1909) and bacteriology (1909--1915) at Howard University Medical School.
Split into simpler sentences: He retained his post at USNM until 1912. Lyon taught physiology (1903--1904 and 1907--1909) and bacteriology (1909--1915) at Howard University Medical School.