Primary Objective: To find a medium, defined as clearly as possible in terms of its nitrogenous components, which will support growth of a cellulolytic rumen bacterium. Secondary Objectives: 1. To test an hypothesis that the optimum nitrogenous nutrient balance for a strongly heterotrophic organism is that mixture of the basic structural molecules ( amino acids, purines, and pyrimidines ) which most closely approximates the composition of the organism itself. 2. To apply this hypothesis toward the goal set in the first objective. / Master of Science