The year 1674, marks the birth of microbiology when Anthony van Leeuwenhoek, a Dutch cloth merchant, looked at a drop of lake water through a glass lens which he had ground.
What he observed through this simple magnifying lens was an amazing sight and that was perhaps the first time that man ever had a glimpse of the world of the microbes. In a series of letters to the Royal Society of London, Leeuwenhoek described a variety of organism referring them as 'animalcules', which we know them today as microorganisms such as protozoa, algae, yeast and bacteria. His description was so precise that it is now possible to assign them into specific genera without any additional description.
Leeuwenhoek had little formal education but his keen interest in nature made him to examine a variety of materials. Glass grinding and preparation of lenses was his hobby and this led him to the assembly of about 400 simple microscopes. The earliest microscope the he constructed was made of a sperical lens mounted on two plates. His early microscopes were only magnifying glasses capable of enlarging objects from about 50 to 300 times.
Leeuwenhoek had discovered the microbial world through the use of a simple microscope containing a single biconvex lens of short focal length. His microscopes were too simple and did not magnify the objects sufficiently. Further, understanding the structure and role of the microbes could not have occurred if the microscopes were not improved. Prior to Leeuwenhoek, the Dutch spectackle maker Janssen(1590)had found that a second lens could greatly enlarge the image formed by a primary lens. By this,50-100 fold magnification were possible. Leeuwenhoek had observed the microorganisms with the microscope with multiple lenses and observing biological specimen goes to Robert hook. Athough Hooke's the knowledge of microorganisms and microscopy developed slowly. it was only around 1820, that microscopes which are the forerunners of present day's compound microscope came into being.
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