FROM time to time certain organisms, all closely similar, have been encountered in this laboratory which from their unusual occurrence and unfamiliar behaviour presented some difficulty in their identification. An account of some of them and of the cases from which they were derived is here given, and an attempt is made to correlate the organisms. If the result of the investigation shows that they belong to a single group of pathogenic bacilli, the important fact will be illustrated from the short accounts of the cases that a wide range of clinical manifestations may be met with in association with this group of bacteria.