Ring a ring o’ roses,

A pocket full of posies.

Ashes to ashes.

We all fall down!

In 17th century London children chanted this grim nursery rhyme about the fearsome bubonic plague (black death) that was claiming so many victims in their city.

Until then London had somehow been spared from the effects of this dreaded killer disease that had swept across Asia and Europe several times in the preceding centuries, taking populations of whole towns and villages in its wake. But not this time.

The “ring a ring o’ roses” meant that a victim’s skin had a black spot circled by a bright red ring, a sure sign that a person had the disease. In 1665 the plague claimed thousands of Londoners each month, and doctors were helpless because there was no known cure for the disease.

Some people stuffed their pockets with posies, because they thought that flowers would protect them from the black death. However, it didn’t work, and the victims’ skin turned the color of ashes (“ashes to ashes”) and they soon died. Frightened people fled the overcrowded city, scattering into the countryside. Nearly everyone left to escape when the black death struck, leaving no one to bury the dead. Entire cities became ghost towns.

Friendly people grew to be fearful strangers. One town leader said, “Shut your doors against your friends, and if a man passeth over the fields, avoid him as you would in time of war.”

In September of 1666 London suffered another disaster when the house of the king’s baker on Pudding Lane caught fire. This caused the worst fire in London’s history and within three days four-fifths of the city lay in ashes.

When the smoking embers died down the black death had vanished as mysteriously as it had appeared. People cautiously returned to the city.

Doctors shook their heads, puzzled. They did not know what caused the plague nor could they explain why it left after the fire.

The first steps toward understanding and controlling this puzzling disease were made by Anton van Leeuwenhoek, a young man from Delft, Holland. He ran a dry goods store there and worked as a janitor at the town hall. In his spare time Leeuwenhoek made fine microscopes that proved to be the most precise in the world. His first important discovery came when he examined a drop of canal water. In the water he saw tiny moving creatures (bacteria) that could not be seen with the eyes alone.

“I must say for my part,” he wrote to the Royal Society, England’s meeting place for great scientists, “that no more pleasant sight has ever yet come before my eye. I judge that some of these little creatures are a thousand times smaller than the smallest mite.”

Leeuwenhoek estimated that a drop of water contained a million of the little animals. But Christian Huygens, a scientist of the Royal Society, balked at his report. He, too, was a microscope maker, but he couldn’t see the bacteria described by Leeuwenhoek.

Twenty-six microscopes were sent to the Royal Society by Leeuwenhoek. Then for the first time members of the society were able to see for themselves the little living creatures in a drop of water. Huygens apologized by saying, “I was wrong. The little animals do exist.” And the Royal Society elected Leeuwenhoek a member.

But a more astonishing discovery was yet to come. At the very limit of his microscope’s power, Leeuwenhoek saw strange little rod-shaped bodies that moved and grew and were much smaller than anything previously seen. He discovered that some of the tiny creatures lived on fleas!

These little pests prompted the English writer, Jonathan Swift, to write the following poem:

So, Nat’ralists observe, a Flea

Hath smaller Fleas that on him prey;

And these have smaller fleas to bite ’em

And so proceed ad infinitum.

Leeuwenhoek became famous. Visitors came from far away to meet him and to bring him different objects to observe under his microscopes. The queen of England paid him a visit, as did Peter the Great, ruler of Russia.

Some of the local people, however, complained about Leeuwenhoek’s activities. They thought he was wasting his time. “We suffer from diseases,” they cried, “while he plays with a useless hobby!”

But Leeuwenhoek’s microscopic observations were far from being useless. Without the aid of his precision-built microscopes, the bacteria carried by rats that caused the black death wouldn’t have been discovered, for it was the fleas jumping from rats onto humans that caused the disease to spread. When the great fire killed all the rats in London, the plague of the black death left too.

Today, the bubonic plague can usually be prevented. Special metal disks are slipped around the mooring ropes of ships to keep all rats from boarding the vessels or from being transported to other countries.

Personal cleanliness is important too. It helps to keep our bodies free of fleas and disease-carrying bacteria.

Illustrated by Tom Pratt