Any branch of biology depends for its progress on the development of new
concepts and to a lesser, but sometimes crucial, extent on the
elimination of erroneous notions. Understanding the roles of bacteria
required first the observation that such minute creatures existed, and
subsequently the exper- imental demonstrations that their presence was
necessary for the occurrence of particular phenomena. In this first
volume, the authors review the development of scientific understanding
of the role of microbes as agents of diverse natural processes. Notably
absent is a separate review of the history of microbes as agents of
disease, a his tory available in many other publications. Regrettably
absent is a review of the his tory of microbes as agents of inorganic
transformations, a serious omission that resulted from the illness of
the prospective author late in the preparation of this volume. The topic
will of course be treated in later volumes, although not predominantly
in a historical manner. Otherwise, the emphasis in this volume is on the
history of understanding interrelationships between modes of bacterial
existence and the inanimate environment. These relationships were
established long be fore multicellular, differentiated or- ganisms
appeared as potential microbial habitats, and their recognition and
elucidation contributed greatly to the widened appreciation of bacterial
di- versity and the importance of these simpler creatures to the
physiochemical conditions of the biosphere.