The purpose of this study was to develop a biological system for conversion of natural cellulosic wastes to products that can be utilized as nutrients by animals. Efforts toward development of a fermenter for the growth of an anaerobic cellulolytic bacteria on cellulosic materials were not successful because the yield of bacterial cells and other products was too low. However, a repression mechanism was demonstrated on the synthesis of cellulose that prevents accumulation of sugar from the hydrolysis of cellulose. The strictly anaerobic bacteria Ruminococcus albus was successfully grown on petri plates. Trichoderma viride cultures also were used in laboratory experiments for degradation of cellulose.