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  Anton Van Leeuwenhoek Microscopes

Anton Van Leeuwenhoek and his Microscopes:

Anton van Leeuwenhoek (1632 - 1723) a contemporary of Robert Hook was born in Delft, Holland.  Leeuwenhoek was a successful entrepreneur and qualified himself as a examiner and the official wine taster of Delft, Holland and in the year 1660 he was appointed chamber lane to chief judge, the sheriffs and the law officers of Delft. He held the place for thirty-nine years.  He had little proper education and never attended a university.  He was unaware of any language except Dutch. He was lucky that his work was recognized in his lifetime itself.  A society for scientific work publication was established in England and was termed as Royal society. The society invited Leeuwenhoek to communicate his examination to its members.  He was chosen as a fellow of the society in the year 1680.  For approximately fifty years until his death in the year 1723, Leeuwenhoek transmitted his discoveries to the royal society in the form of lengthy letters written in Dutch. Most of his discoveries were transformed and published in English in the proceedings of the royal society. Leeuwenhoek prepared glass lenses by grinding and mounting them into brass contraptions and he termed them as microscopes and almost spherical lens (a) was mounted among two small metal plates. The specimen was located on the adjustable needle mounted above the lens. The needle is a blunt pin (b) and was brought into focus by manipulating two screws (c) and (d) (shown in figure).No change of magnification was possible and the magnifying power of all microscope being an intrinsic property of its lens.

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                                      Figure: Drawings of a microscope employed by Anton van Leeuwenhock

He was capable to view the specimens on the blunt pin by holding the microscope very near to his eye and squinted via the lens. His microscope was capable to magnify from around 50 to 300 times. Leeuwenhoek made hundreds of such instruments. Microscopy was an attractive hobby for Leeuwenhoek and he spent a big part of his life making microscopes, observing the microscopic world and sustained records of his observations in simple language. He made explanation on the structure of seed and embryos of plants, small invertebrate animals, Red blood cells, and spermatozoa.

Although his biggest discovery is of the microbial world of ani-malcules. He sends the 18th letter to the society on October 9, in the year 1676 and provides the first description of unicellular animals like protozoa and the smaller microorganisms like bacteria. He looked at water samples from fresh water from river, well-water, seawater and rainwater.

His explanations were accurate. One of Leeuwenhoekís most publicized observations was of bacteria from human mouth (as shown in figure).  He explained rod shaped bacteria as bacilli, spherical bacteria like cocci and bacteria with spiral body which resemble cork screws as spiroketes. Beginning in the 1670s Leeuwenhoek wrote many letters to the Royal society in London and persistent his studies until his death in the year 1723 at the age of 91.

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Figure: Anton Van Leeuwenhoekís drawings of bacteria published in the year 1684 that he termed as ianimalcules.

Nine of the expected 500 Leeuwenhoekís microscopes and all of his drawings still exist.  Leeuwenhoek made microscopes which had a magnification of 266 x. Though from the details of his drawings and sketches it is revealed that he must have made considerably more powerful microscopes which have been lost.

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         Figure: Drawings of Pasteuris swan neck flask employed in spontaneous generations experiment.

Louis Pasteur (1822-1895), a Professor of Chemistry in France, via his famous swan neck flask experiments contradicted the theory of abiogenesis. He boiled the nutrient solution in container with all along narrow swan neck opening and unfiltered or untreated air could pass into the flask. The germs settled in the swan neck and therefore no microbes appeared. He also filtered the air via cotton plug and dropped it in nutrient solution and establishes that micro organisms identical to those in air appeared. Hence he concluded that air contain microbes which contaminated the boiled infusions. Pasteuris experiment contradicted the spontaneous generation theory once for all.  John Tyndall exhibited (1820-1893) which dust contained the germs and when no dust exists, sterile broth remained without microbial growth for a long time. Eventually the theory of abiogenesis was discarded for microbes and also Biogenesis was accepted. Cogniard Latour noticed budding in yeast cell explaining that cells occur from preexisting cells.

 

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