THE genus Salmonella comprises a large number of gram-negative enteric bacilli pathogenic to both man and animals. They are grouped together by reason of similarities in biochemical behavior, but more definitively by reason of the specific antigens that they possess in common. Differentiation within the group is based on variations, often minor, in these biochemical and antigenic characteristics. The National Salmonella Center has available for distribution over one hundred and sixty different species or types, not all of which, however, have yet been proved pathogenic to man.1 In the accepted classification Salmonella enteritidis falls into Group D, for its somatic . . .