Complex sentence: Harry Anslinger denounced Mayor Fiorello La Guardia, the New York Academy of Medicine and the doctors who had worked for more than five years on the research, saying that they should not conduct more experiments or studies on marijuana without his personal permission.
Split into simpler sentences: Harry Anslinger denounced Mayor Fiorello La Guardia, the New York Academy of Medicine and the doctors who had worked for more than five years on the research. Anslinger said that they should not conduct more experiments or studies on marijuana without his personal permission.