mistrusted and their significance not conceived. As microscopic
organisms, there were no reasons for considering them of any more
importance than any other small animals or plants, and their
extreme minuteness and simplicity made them of little interest to
the microscopist. On the other hand, their causal connection with
fermentative and putrefactive processes was entirely obscured by
the overshadowing weight of the chemist Liebig, who believed that
fermentations and putrefactions were simply chemical processes.
Liebig insisted that all albuminoid bodies were in a state of
chemically unstable equilibrium, and if left to themselves would
fall to pieces without any need of the action of microscopic
organisms. The force of Liebig's authority and the brilliancy of
his expositions led to the wide acceptance of his views and the
temporary obscurity of the relation of microscopic organisms to
fermentative and putrefactive processes. The objections to
Liebig's views were hardly noticed, and the force of the
experiments of Schwann was silently ignored. Until the sixth
decade of the century, therefore, these organisms, which have
since become the basis of a new branch of science, had hardly
emerged from obscurity. A few microscopists recognised their
existence, just as they did any other group of small animals or
plants, but even yet they failed to look upon them as forming a
distinct group. A growing number of observations was accumulating,
pointing toward a probable causal connection between fermentative
and putrefactive processes and the growth of microscopic
organisms; but these observations were known only to a few, and
were ignored by the majority of scientists.

It was Louis Pasteur who brought bacteria to the front, and it was
by his labours that these organisms were rescued from the