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Twenty-nine strains of Corynebacterium diphtheriae isolated from throats and 29 strains from skin lesions, the latter mainly from communities of low socio-economic status in tropics and cold climates, have been examined for the property of adherence to human buccal epithelial cells. All throat strains showed adherence. In contrast, strains from skin lesions were predominantly poor adherers. These results indicate that strains of C. diptheriae from throats must now be added to the important group of pathogens which possess the property of adherence to surface epithelial cells of mucous membranes, thus providing an essential first step in the process of colonizing their hosts. The possible role of this phenomenon of adherence to bucco-pharyngeal epithelial cells in the evolution of the host-parasite relationship of C. diphtheriae is discussed.

A method of freeze-drying is described by which the activity of a series of eorynebacteriophages was maintained over a test period of 30 months, whereas some of these strains became inactive if stored as liquid filtered lysates at 4 degrees C., or frozen and held at -25 degrees C.

The exotoxins produced by ten strains of C. ulcerans (two human, six bovine and two equine) have been studied. On the criteria of toxin-antitoxin neutralisation and immunoprecipitation tests using highly specific diphtheria and C. ovis antitoxins with crude toxic filtrates, (NH4)2SO4 concentrates, and partially purified chromatographic preparations of these, together with the presence or absence of inhibition of the action of staphylococcal beta-haemolysin, and the reaction produced when injected intradermally into rabbits, two toxins could be identified, namely diphtheria toxin and C. ovis toxin. There was no evidence for the production of a third toxin specific for C. ulcerans. Five strains produced both diphtheria and C. ovis toxins. In four diphtheria toxin predominated, but in the fifth C. ovis toxin predominated. Two strains produced only diphtheria toxin and two only C. ovis toxin, though there was good but not complete evidence that a third strain (Revell) also fell into this latter group. Considerable variation occurred in the concentration of each toxin and, where both were present, in the proportion of each.