REVERSION OF KELLOGG'S COLONIAL TYPES O F

DIFFERENCES in the colonial morphology of Neisseria gunorrhoeae were first noted by Wassermann (1 898) and Lipschiitz (1 904) ; since then a great deal has been learned about the variations in colonies of gonococci and their significance. In 1925 Atkin described two forms of colony and reported that one of these predominated in recently isolated cultures. Kellogg et al. (1963) showed a clear relationship between colonial morphology and virulence for human volunteers. It is now accepted that Kellogg's colony types 1 and 2 are infective whereas types 3 and 4 are not. Whilst studying the possible determinants of virulence, Jephcott and Reyn (1971) reported a fifth colonial type. Little was known about the pathogenicity of this type, but it was generally believed to be a de-graded type similar to types 3 and 4. With the development of a liquid medium that supported the growth of gonococci for longer periods than did most solid media, an opportunity arose to study the behaviour of different colonial types in the unusual environment of a liquid culture. MATERIAL AND METHODS Media. The liquid medium (Hafiz and McEntegart, 1977) consisted of Proteose Pepton