a1 National Institute for Medical Research, London, N.W.3.
1. Two pure strains of Entamoeba coli, differing in their accompanying bacterial flora and experimental history, but identical morphologically, have been tested with emetine hydrochloride in vitro.
2. In a buffered and wholly liquid medium, with a pH varying between 6·8 and 7·2, emetine hydrochloride was found to be toxic to E. coli in dilutions between 1 : 300,000 and 1 : 600,000, the toxicity increasing with the alkalinity of the medium.
3. It is therefore concluded that emetine is about 16 times as toxic in vitro to E. histolytica as it is to E. coli.
(Received August 22 1929)