Abstract
1. A strain of Bacillus cereus has been isolated that can produce tryptamine when grown in a broth containing tryptophan. 2. The conditions of culture under which this conversion is optimum, as well as the general pathways of tryptophan metabolism by this micro-organism, have been examined, and the information obtained has been used to obtain the first demonstration of cell-free tryptophan-carboxy-lyase activity. 3. The significance of these findings both to the current attempts to elucidate the pathways of metabolism of tryptophan in higher plants and to the published generalizations about the previously studied amino acid carboxy-lyases is discussed.