India Company's ships, but also because of the fantastic stories that he relates. An example; Jan de Doot, a blacksmith in Amsterdam, was in such pain from a bladder stone, that he sharpened a knife and removed it himself because he refused to be the victim of the 'stone cutters'. These were the barber-surgeons who performed such procedures but had a high death rate. To everyone's surprise, Jan de Doot survived this operation which was said to produce a stone the size of an egg. A painting illustrating this story is in the collection of the Anatomy Museum of Leiden. Tulp minutely described the condition we know as migraine, the devastating effects of tobacco smoking on the lungs, and reveals an understanding of human psychology in a description of the placebo effect. Tulp also discovered the ileocecal valve at the junction of the large and small intestines, still known as Tulp's valve. While Tulp made observations of various diseases, treatment often continued in the age-old way. His description of the symptoms of Beriberi in a Dutch seaman, for example, went unnoticed until the cause (vitamin B1 deficiency) was recognized two hundred years later by Christiaan Eijkman. Public office Partially as a result of the success of his books, Tulp became Mayor of Amsterdam in 1654, a position he held for four terms. His son Dirck married Anna Burgh, the daughter of Albert Burgh, another Mayor of Amsterdam who had, like Tulp, studied medicine in Leiden in 1614. In 1655 Tulp's daughter Margaretha married Jan Six, whom he helped become a magistrate of family affairs in Amsterdam. Years later, Six would also become Mayor of Amsterdam. Tulp, impressed by his behaviour, invited Paulus Potter to come to Amsterdam, after a quarrel in the Hague. In 1673 Tulp was admitted to the Governing Committee of the Republic in The Hague. Legacy and death Tulp is buried in the New Church of Amsterdam. Joost van den Vondel, a period poet, wrote several verses about him. Besides the famous painting by Rembrandt, there are more paintings, as well as marble and bronze statues of him. The Holstein painter Jurriaen Ovens painted him twice, and also painted his son and daughter. Artus Quellijn also made a portrait. References Amstelredamensis Observationes Medicae, Nicolai Tulpii, Amsterdam Elzevier, 1641 Geneeskundige Waarneemingen van Nikolaas Tulp, Oud Burgermeester der Stad Amsterdam. Naar den zelfden Druk uit het Latyn vertaalt. Hier