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  The difference between veins and arteries is discovered.
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  Discovered the difference between measles and small pox.
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  The discovery and distinction of smallpox.
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  People now specialize and get paid for being a surgeon which allows for more in depth study.
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  Invents spectacles.
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  A plague that devastated Europe and wiped out 90% of the population in some areas.
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  He made the Vetruvian Man.
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  Dissected the human body to correct the conceptions from ancient times
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  Microscope was made to help see small bacteria.
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  First to argue that blood circulates around the body.
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  Discovered the small pox vaccine.
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  Stethoscope invented for listening to lungs and heart.
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  A dentist discovers the first anesthetic.
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  Invented pasteurization to prevent organisms causing.
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  Founder of modern nursing.
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  Insulin first used to treat diabetes.
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  Firtst vaccines for pertussis
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  Discovered penicillin (big deal).
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  The virus that causes aids is identified.
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  The first mammal cloned from an adult cell.