body, such as inside the stomach. Harré suggests that van Helmont's theory was "very near to our modern concept of an enzyme". Van Helmont proposed and described six different stages of digestion. Disputed portrait In 2003, the historian Lisa Jardine proposed that a portrait held in the collections of the Natural History Museum, London, traditionally identified as John Ray, might represent Robert Hooke. Jardine's hypothesis was subsequently disproved by William B. Jensen of the University of Cincinnati and by the German researcher Andreas Pechtl of Johannes Gutenberg University of Mainz, who showed that the portrait in fact depicts van Helmont. Honours In 1875, he was honoured by Belgian botanist Alfred Cogniaux (1841–1916), who named a genus of flowering plants from South America, Helmontia (from the Cucurbitaceae family). See also Franciscus Mercurius van Helmont, his son George Thomson (physician) (c. 1619–1676), English physician and notable advocate of Helmontian medicine Timeline of hydrogen technologies Pneumatic chemistry Notes References Further reading Steffen Ducheyne, Johannes Baptista Van Helmonts Experimentele Aanpak: Een Poging tot Omschrijving, in: Gewina, Tijdschrift voor de Geschiedenis der Geneeskunde, Natuurwetenschappen, Wiskunde en Techniek, 1, vol. 30, 2007, pp. 11–25. (Dutch) Friedrich Giesecke: Die Mystik Joh. Baptist von Helmonts, Leitmeritz, 1908 (Dissertation), Digitalisat. (German) Eugene M. Klaaren, Religious Origins of Modern Science, Eerdmans, 1977, . Moore, F. J. (1918). A History of Chemistry, New York: McGraw-Hill. Pagel, Walter (2002). Joan Baptista van Helmont: Reformer of Science and Medicine, Cambridge University Press. Redgrove, I. M. L. and Redgrove, H. Stanley (2003). Joannes Baptista van Helmont: Alchemist, Physician and Philosopher, Kessinger Publishing. Johann Werfring: Die Einbildungslehre Johann Baptista van Helmonts. In: Johann Werfring: Der Ursprung der Pestilenz. Zur Ätiologie der Pest im loimografischen Diskurs der frühen Neuzeit, Wien: Edition Praesens, 1999, , pp. 206–222. (German) The Moldavian prince and scholar, Dimitrie Cantemir, wrote a biography of Helmont, which is now difficult to locate. It is cited in Debus, Allen G. (2002) The Chemical Philosophy: Paracelsian science and medicine in the sixteenth and seventeenth centuries. Courier Dover Publications, on pages 311 and 312, as Catemir, Dimitri (Demetrius) (1709); Ioannis Baptistae Van Helmont physices universalis doctrine et christianae fidei congrua et necessaria philosophia. Wallachia. Debus refers to a suggestion of his colleague William H. McNeill for this information and cites Badaru, Dan (1964); Filozofia lui Dilmitrie Cantemir. Editura Academici Republicii Popular Romine, Bucharest pages 394–410 for further information. Debus further remarks that the work of Cantemir