Complex sentence: In 1883 and in the following 40 years, Émile Roux became closely involved with the creation of what was to be the Pasteur Institute, and shared his time between biomedical research and administrative duties.
Split into simpler sentences: In 1883 and for the following 40 years, Émile Roux became closely involved with the creation of what was to become the Pasteur Institute. He divided his time between biomedical research and administrative duties.