Roy Sawyer. Portrait of Dr Roy T. Sawyer, the American zoologist who was mainly responsible for re-establishing the use of leeches in medicine. He is holding two Amazon leeches, Haementeria ghilianii; this is the world's largest species of blood-sucking leech and was rediscovered by Sawyer during an expedition to South America. It is one of several species of leech that Sawyer has studied. He breeds leeches to treat accumulations of blood (haematoma), and extracts drugs from their saliva which prevent blood clotting. He was fascinated by leeches from an early age, and in 1984 founded the world's first large-scale leech farm, Biopharm, in Wales, UK. Photographed in 1986.