“…Large body formation in P. vulgaris OX19 occurs in the same manner under the influence of penicillin as previously described under normal cultural conditions by Stempen and Hutchinson (1951). The lack of further development of the large bodies on nutrient agar containing penicillin is in agreement with reports on other strains of Proteus (Qrskov, 1947;Dienes, 1949;Tulasne, 1949a;Fleming et at., 1950;Pulvertaft, 1953;von Prittwitz and Gaffron, 1953) in which development into rods was obtained only when the spherical forms were transferred to media not containing penicillin.…”