Complex sentence: In the years 1954-1961 led the Czechoslovak Academy of Sciences Laboratory of Parasitology, in letech 1952-1959 he was the Secretary of the biological section of the Czechoslovak Academy of Sciences, in the years 1960-1961 was its chairman.
Split into simpler sentences: In the years 1954-1961 he led the Czechoslovak Academy of Sciences Laboratory of Parasitology. In letech 1952-1959 he was the Secretary of the biological section of the Czechoslovak Academy of Sciences, and in the years 1960-1961 was its chairman.