Definition: A microscopic vegetable organism, belonging to the class
Algae, usually in the form of a jointed rodlike filament, and found in
putrefying organic infusions. Bacteria are destitute of chlorophyll,
and are the smallest of microscopic organisms. They are very widely
diffused in nature, and multiply with marvelous rapidity, both by
fission and by spores. Certain species are active agents in
fermentation, while others appear to be the cause of certain infectious
diseases. See Bacillus.