An uncommonly rare leech jar composed of blown glass from Germany.

Bleeding by the application of leeches was common practice throughout Europe in the 17th, 18th, and 19th centuries. According to the humoral theory proposed by Hippocrates circa 400 BC, bloodletting could restore a balance of the four humours (black bile, yellow biles, phlegm, and blood) in order to maintain good health.

The leeches would attach themselves to the inward-pointing glass protrusions, which had perforations at their tips which allowed the leeches enough oxygen to breathe.

Similar examples are held in the Wellcome Collection and the London Science Museum.

• From the Lusignan collection