In a previous communication it has been shown that among intestinal bacteria of the coliform group Bacillus paracoli and Bacterium coli mutabile are at least four times more common in the insane than in the general community, and that they are to be found in great number in at least one-half of the former during acute phases of illness. It was suggested that both the illness and the increase of these bacteria might be due to a third factor, namely, to the action of some other intestinal organism, since certain workers had found that colon bacilli when grown on phenol varied to the mutabile type, and it is well known that phenol is formed in the intestine by certain bacteria.