This jar was made for apothecaries to store leeches. Leeches are part of the Class Annelida of segmented worms which feed on the blood of other animals. Leeches are so well adapted to accessing the blood of mammals that humans, who have been practising bloodletting for 3000 years, began using then for this practice about 2500 years ago.
Bloodletting has been practiced for cultural and medical reasons, the latter becoming a very widely used treatment for innumerable ills. It was a practice heavily associated with the Hippocratic humoral theory of medicine. A healthy body had all of it's elements - blood, yellow bile, black bile and phlegm - in balance. Galen, the Roman physician and philosopher whose theories were the medical canon until the 17th century, believed that many common symptoms now known to be that of the common cold were caused by a build up of blood. Bloodletting was believed to release the excess blood and cool down the body.
Leeches can extract several times their body weight in blood - painlessly, so they were the ideal foil for the bloodletting surgeon's work. Leeching could be practiced at home by anyone, unlike venesection which required a surgeon or cupper.
Although they are no longer used for bloodletting in medicine - the practice ended in the late 19th century - they are used in skin-graft surgery to encourage blood flow and after microsurgeries to reduce swelling.
Damian McDonald, Curator, August 2013
Updated: Stephanie Chinneck, Curatorial Volunteer, March 2017