Bubonic plague infection causes tiny blood vessels in the hands and fingers to clog up and cut off circulation. Without blood, the flesh dies and turns black (called "gangrene"). This is why in the Middle Ages bubonic plague was called "the Black Death." In the 14th century it killed an estimated 25 million people, or 30–60% of the European population.
Thanks to the miracle of animated gifs, we can unambiguously describe the progression of The Plague! With the addition of Asia to the map, you really get a sense for how truly widespread this pandemic was. It was not simply European or English history as I was taught in school (though it did wipe out 50% of the English population!) but in fact ravaged large portions of Asia, Africa, and Europe.
10 things you (probably) didn’t know about the Black Death - It is one of the worst catastrophes in recorded history – a deadly plague that ravaged communities across Europe, changing forever their social and economic fabric. But how much do you know about the Black Death? | History Extra
Ring Around The Rosie. This rhyme dates back to the Great Plague of London in 1665. The symptoms of bubonic plague included a rosy red ring-shaped rash, which inspired the first line. It was believed that the disease was carried by bad smells, so people frequently carried pockets full of fresh herbs, or "posies." The "ashes, ashes" line is believed to refer to the cremation of the bodies of those who died from the plague.