We are learning  about Microbiology. This  is the study of bacteria, viruses, and other microbes that are invisible to the eye. These tiny creatures are everywhere, even on you and in you! Don’t worry, most microbes are harmless to humans.

Less than 500 years ago, people believed that illnesses were caused by evil spirits or poisonous gases. Today, we know that many illnesses are caused by germs and microscopic viruses and bacteria that we cannot see. This is possible because of the microscope.

The first microscope was probably invented by Hans and Zacharias Jansen in the 1600s. These early microscopes had compound lenses, which means they used two pieces of glass. The microscopes were not very powerful. They could magnify something only 20 times.

In the late 1660s, Antony van Leeuwenhoek made his own powerful microscope from one lens. His microscope could magnify things up to 200 times. He discovered cells in blood, animal tissue and plant tissue. He even discovered bacteria by looking at plaque from his own teeth.

Today, people still use compound microscopes, but they are much improved.

There are trillions of mini-animals and microbes that you cannot see. The microscopic world includes viruses, bacteria, protists, microscopic fungi and mini-animals.

Today’s compound microscopes use light to illuminate organisms. Light microscopes are so powerful that they can magnify something by 1,000 times.

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A micrograph is a photograph of something seen in a microscope.