THE DISCOVERY OF MICROORGANISMS

• Some investigators suspected their existence and responsibility for disease.
• Roman philosopher Lucretius (about 98–55 B.C.) and the
  physician Girolamo Fracastoro (1478–1553) suggested that disease  caused by invisible living creatures. 
• Earliest microscopic observations appears between 1625 and 1630 on bees and weevils by the Italian Francesco Stelluti,
  using a microscope probably supplied by Galileo. 
• In 1665, First drawing of microorganism was published in Robert Hooke'S Micrographia.
• First person to publish,accurate observations of microorganisms was the amateur microscopist Antony van Leeuwenhoek (1632–1723) of Delft, The Netherlands.
• Leeuwenhoek earned his living as a draper and haberdasher  spent much of his spare time constructing simple microscopes composed of double convex glass lenses held between two silver plates.
  
• His microscopes could magnify around 50 to 300 times, and he may have illuminated his liquid specimens by placing them between two pieces of glass and shining light on them at a 45° angle to the specimen plane.
• A form of dark-field illumination in which the organisms appeared as bright objects against a dark background and made bacteria clearly visible.
• Beginning year 1673, Leeuwenhoek describing his discoveries to the Royal Society of London. It is clear from his descriptions that he saw both bacteria and protozoa.
• Leeuwenhoek’s observations was the development of microbiology essentially languished for next 200
  years.
• Little progress made primarily because microscopic
  observations of microorganisms do not provide sufficient information to understand their biology.
• Techniques for isolating and culturing microbes in the laboratory were needed.
• Many of these techniques began to be developed as
  scientists grappled with conflict over the Theory of
  Spontaneous Generation. 
• This conflict and  subsequent studies on the role played by microorganisms in causing disease ultimately led to what is now called the Golden Age of Microbiology.  

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