Microbial Antagonisms and Antibiotic Substances.

The introductory chapters are a summary of the environmental factors which influence the microbiologic population in soils and water basins. It is emphasized that, in the struggle for existence among micro-organisms, one species may gain ascendancy by the production of substances detrimental to the growth of other species. Some of these substances have been isolated and designated as antibiotic. The remainder of the book is principally a review of the literature concerned with the various properties, chemical compositions and modes of action of these substances. Some antibiotics are of only theoretic interest. Others, especially penicillin, streptomycin and tyrothricin, have additional interest because of their effectiveness in the treatment of certain infectious diseases of plants, animals and human beings. The study of these materials, and of the innumerable others, not yet isolated in purified form from their natural sources, has led the author to conclude with good reason that the work