<P> Bloodletting gradually declined in popularity over the course of the 19th century, becoming rather uncommon in most places, before its validity was thoroughly debated . In the medical community of Edinburgh, bloodletting was abandoned in practice before it was challenged in theory, a contradiction highlighted by physician - physiologist John Hughes Bennett . Authorities such as Austin Flint I, Hiram Corson, and William Osler became prominent supporters of bloodletting in the 1880s and onwards, disputing Bennett's premise that bloodletting had fallen into disuse because it didn't work . These advocates framed bloodletting as an orthodox medical practice, to be used in spite of its general unpopularity . Some physicians considered bloodletting useful for a more limited range of purposes, such as to "clear out" infected or weakened blood or its ability to "cause hæmorrhages to cease"--as evidenced in a call for a "fair trial for blood - letting as a remedy" in 1871 . </P> <P> Some researchers used statistical methods for evaluating treatment effectiveness to discourage bloodletting . But at the same time, publications by Philip Pye - Smith and others defended bloodletting on scientific grounds . </P> <P> Bloodletting persisted into the 20th century and was recommended by Sir William Osler in the 1923 edition of his textbook The Principles and Practice of Medicine . </P> <P> Today it is well established that bloodletting is not effective for most diseases . Indeed, it is mostly harmful, since it can weaken the patient and facilitate infections . Bloodletting is used today in the treatment of a few diseases, including hemochromatosis and polycythemia; however, these rare diseases were unknown and undiagnosable before the advent of scientific medicine . It is practiced by specifically trained practitioners in hospitals, using modern techniques . In most cases, phlebotomy now refers to the removal of small quantities of blood for diagnostic purposes . However, in the case of hemochromatosis, which is now recognized as the most common hereditary disorder in European populations, bloodletting (venesection) has become the mainstay treatment option . In the U.S., according to an academic article posted in the Journal of Infusion Nursing with data published in 2010, the primary use of phlebotomy was to take blood that would one day be reinfused back into a person . This person chosen did not have to be established at the time of the procedure, but this was possible . </P>

Who advocated bleeding to maintain balance of the humours