Complex sentence: He was a student of Alfred Giard at the Ecole Normale Supérieure and a classmate of Maurice Caullery, and from 1892 worked at the Pasteur Institute, initially as an associate demonstrator.
Split into simpler sentences: He was a student of Alfred Giard at the Ecole Normale Supérieure and a classmate of Maurice Caullery. From 1892 he worked at the Pasteur Institute, initially as an associate demonstrator.