Complex sentence: America's first biomedical institute, The Rockefeller Institute for Medical Research, was founded in 1901 with Welch as its first scientific director and with Welch's former Hopkins student Simon Flexner as is first director of pathology and bacteriology laboratories.
Split into simpler sentences: America's first biomedical institute, The Rockefeller Institute for Medical Research, was founded in 1901 with Welch as its first scientific director. Welch appointed his former Hopkins student Simon Flexner as is first director of pathology and bacteriology laboratories.