Bandur, Bojana M. (Massachusetts General Hospital, Boston) and Louis Dienes. L forms isolated from a strain of Serratia. J. Bacteriol. 86:829-836. 1963.-In an L culture isolated from a strain of Serratia, two types of colonies developed, one (S-1) similar to the usual L colonies with the centers embedded in the agar and the other (S-2) similar in gross appearance to the usual bacterial colonies. The S-2 colonies consisted almost exclusively of large bodies and were produced by the direct multiplication of the large bodies. This occurred by enlargement, deformation, and segmentation. The organisms in the two types of L colonies were equivalent, and the type of growth was determined by environmental influences. The high viability of the cultures and the relative lack of autolysis permitted the study of the reproductive processes and the resulting growth under varying conditions. The basic reproductive process, as in other L forms and pleuropneumonia-like organisms, seemed to be the multiplication of small granules, either free or in small or large aggregates enclosed in a common envelope. It was possible to observe clearly the growth of small granules from the large bodies.