When Did Antoni van Leeuwenhoek Discover Bacteria With a Microscope and Where Do Beasties Come From?

In 1683, Antoni van Leeuwenhoek made his greatest discovery. He called them “beasties.”

One day, he put a drop of stagnant rainwater under his microscope and saw “dozens of little animals, swimming and wriggling in that tiny drop of water, wretched beasties, a thousand times smaller than you can see with the naked eye.”

Van Leeuwenhoek had discovered bacteria.

Leeuwenhoek conducted more experiments to see where the beasties had come from because he did not think the rain had brought them.

After weeks of experiments with water from many different sources, he realized that bacteria and other microbes, living things visible only under a microscope, are in the air around us and they fall to Earth on particles of dust.

Leeuwenhoek also found bacteria in human saliva.

In a remarkable observation way ahead of its time, he found that drinking hot coffee seemed to kill off some of the bacteria.

In experiments with shellfish, Leeuwenhoek saw bacteria destroy living things many times their size, but he did not fully understand the significance of these findings.

Neither did his successors, it would be nearly 200 years before French chemist Louis Pasteur convinced the world of the connection between bacteria and disease.

Antoni van Leeuwenhoek used his knowledge of lens grinding to create amazing microscopes that allowed him to view bacteria, which he called “beasties.”

Peter, Czar of Russia, and Queen Anne of England both visited Leeuwenhoek wanting to peer through his microscopes.

Leeuwenhoek was reluctant to let anyone touch his instruments, but since they were royalty, he allowed it.