a1 Bureau of Animal Population, Oxford University
1. The six ‘viruses’, Liverpool, Danysz, London, Ready Rat Relief, Institut Pasteur and Ratin, which are the principal bacterial cultures at present employed for anti-rodent control in Great Britain, have been examined. 2. By means of reciprocal absorption tests all these six strains were found to be serologically identical with S. enteritidis Gaertner, antigenic structure, IX:gom:—. 3. From the results of the fermentation tests, which may be used to subdivide this serological type, Liverpool, Danysz, Ready Rat Relief and Ratin were assigned to the var. danysz subgroup; while the London and Institut Pasteur strains could not be distinguished from the classic S. enteritidis type. 4. Both of these subgroups are pathogenic for man, and evidence is cited which shows quite clearly that human cases of gastro-enteritis have been caused by the use of virus preparations. There are, also, reasonable grounds for believing that these bacterial types may be pathogenic for a number of domestic animals, including some poultry.