Salmonella typhi or S. paratyphi B were found in very large numbers in the faeces of enteric carriers. Of twenty-four carriers, four were found negative by the fullest examination. Of the twenty found positive almost all harboured many millions of bacilli per gram of faeces.

A minute inoculum of one drop (1/50 ml.) of a 1:1000 dilution of faeces on a culture plate only rarely failed to reveal all the positives without the use of an ‘enrichment’ medium and the result of such a procedure was a culture plate with virtually a pure culture of the pathogen.

I am grateful to the Medical Superintendents of the Mental Hospitals at Cardiff, Bridgend and Denbigh, and the Medical Officer of Health for Brecon for submitting specimens for examination.