Herophilus of Chalkaidon first described the Pancreas in around the year 300BC. It was not until some four hundred years later in AD100, that Rufus of Ephesus named the organ. Galen, in AD160, considered diabetes to be due to a weakness in the kidneys. He believed that the 'kallikreas' was a protective organ guarding the great veins. In 1642, Wirsung discovered the pancreatic duct in the human body. At the same time Franciscus de la Boe suspected that it was through this duct that the pancreas secreted juice into the intestine. Langerhans first described the endocrine role of the pancreas in 1869. In 1893, Laguesse suggested that the islet cells produce a hormone. Opie in 1900 was able to show the association between diabetes and failure of the islet cells. In 1909 Jean de Meyer suggested the name 'insuline' for the hormone of the islet cells. In 1922, Banting and Best reported the discovery of 'insulin', and the following year Collip purified it. Murlin was the first to discover pancreatic glucagon in 1923.