所有译文

In the seventeenth century, Antonie van Leeuwenhoek was the first person to see tiny organisms with a microscope.He called them animalcules.Later, scientists in the eighteenth and nineteenth canturies named these animalcules bacteria and protozoa.This was the beginning of the sciences of Bacteriology and Protozoology, the studies of microscopic organismis.Bacteriologists and protozoologists have studied these organisms for many years, but they find it difficult to classify them.