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It's Catching! The Infectious World of Germs and Microbes

It's Catching! The Infectious World of Germs and Microbes — page 7
Secrets of the INVISIBLE WORLD Microbes are invisible to the naked eye but when we zoom in for a closer look we can see their world is a pretty busy place Pull a hair off your head You have about a hundred thousand of them losing one won’t hurt Take a close look at it Pretty thin isn’t it Your hair is about 0 1 millimeters or 100 microns in diameter How does the size of our miniature microbial friends compare Parasites are the biggest of the microbes The average parasite cell measures 10 microns so you could fit ten across a single strand of hair The smallest microbes Viruses The tiniest viruses known to scientists parvoviruses are so little you could fit five thousand of them across the width of one hair Zoom in To actually see microbes scientists need a microscope The first microscope was believed to have been invented by Dutch lensmakers Hans and Zacharias Janssen in 1595 This invention was later improved by Italian scientist Galileo Galilei in 1609 the same basic design is still in use today These machines called optical microscopes or light microscopes illuminate a sample from underneath Light shines through the sample and passes through a series of glass lenses that act like magnifying glasses making the sample appear larger 1010