Although the presence of fungi on stored grain has been known for a long time, the relation of their growth to bin-burning is imperfectly understood. In recent years, however, because of the changes in the methods of handling, much grain has been stored in such condition that molding and bin-burning resulted. Common observation showed that the molding and heatingt occurred approximately at the same time, indicating a possible interdependence of one upon the other. Grain in elevators, in farmers' granaries, and in transit, all were similarly affected with a correspondingly great loss. The problem, therefore, was a broad one, necessitating the consideration of the relationship between the molds found on bin-burned grain and the production of "heating," the environmental factors favorable to mold growth, and the effects produced. It is undoubtedly true that temperatures produced in the bin are due to the interaction of several factors. These include the heat of germination itself and temperatures generated by the growth of molds developing on the grain saprophytically. The present investigation was undertaken with the object of isolating and evaluating the role of each of these two sources of heat in the temperature increases occurring in stored grains. The fact that molds may generate high temperatures when grown on suitable organic substances has often been shown in the past. Mention only need be made of the work of COHN (4) on barley, MORGENTHALER (14) on wheat, rye and speltz, McHARGUE (12) and THOM and LE FEVRE (19) on corn meal, KONIG (10) iwith cotton, and MIEHE (13) on hay to indicate the numerous workers and the wide range of materials on which this phenomenon has been observed. However, there seems to have been some idea that living seeds would not serve as a suitable medium for mold growth.