All of the intermediates of the citric acid cycle are shown to be present in the mycelium of 6-day cultures ofP.blakesleeanusgrown on glucose and on ammonium sulfate, and fed non-radioactive acetate on the fourth and fifth days and acetate-1-C14on the fifth day of incubation.The concentration of organic acids and certain amino acids, and their specific activity is reported. The high activity of the latter is thought to indicate the presence of a highly labeled pool of nitrogen compounds persisting from the early anabolic reactions after acetate-1-C14administration.