The demise of bloodletting.

Bloodletting was a practice favoured by doctors and barber-surgeons for many centuries, and is now, perhaps surprisingly, still employed for a few specific indications. The effectiveness of bloodletting for treating diseases such as pneumonia was convincingly challenged in the mid-nineteenth century, but medical conservatism ensured the practice continued well into the twentieth century. As late as 1942, a famous medical textbook considered bloodletting appropriate treatment for pneumonia.