It has been shown in the preceeding paper¹⁾ that chemotherapeutic agents, comprising of antibiotics and synthetic compounds, may be classified into 3 groups or 6 types according to their ability to produce morphological changes in Escherichia coli strain B. It was found that antitumor agents belonged mostly to the group capable of producing elongation of E. coli cells, i.e. Types A,B and C. The antimicrobial agents belonged to the group causing agglomeration of E. coli cells, i.e. Types D and E. It was also suggested that the phenomenon of cell-elongation can be applied to the screening of anticancer substances. This paper deals with the relationship between the morphological changes in E. coli and antitumor or antimicrobial activity when tested with the culture filtrates of soil streptomyces by several screening methods.

During the course of our study on soil microorganisms for isolation of antibiotic substances, an actinomycete culture which produces sporangia was isolated. It differs from the sporangia produced by the Streptosporangium species described in literature in the respect that in this case the sporangia has the tendency to fuse together.

This report is concerned with the taxonomy of the new species.