Credit: Wellcome Library, London. Wellcome Images images@wellcome.ac.uk http://wellcomeimages.org Dogs with their keepers at the Physiology Department, Imperial Institute of Experimental Medicine, St Petersburg.

Ivan Petrovich Pavlov (1849-1936) was a Russian physiologist who won the Nobel Prize in 1904 for his research work on digestion. Most of his research was carried out on dogs. He would attach a tube to the salivary gland (under the dog's ear), and measure the amount of saliva produced in response to different stimuli. For instance, if before giving the dog food, Pavlov rang a bell, the dog would eventually salivate when the bell was rung even if no food was offered. The salivation was given a Russian name meaning "conditional reflex", i.e. an involuntary action which always occurred under particular conditions. Pavlov was able to carry out this work thanks to two wealthy philanthropists: Prince A.P. Ol'denburgskii, who paid for the building of the Imperial Institute of Experimental Medicine at St Petersburg in 1891, and the Swedish industrialist Alfred Nobel, who paid for the construction of a large new physiology building in 1893-1894. It was in that building, with a spacious animal house, that Pavlov was able to employ a relatively large staff to help with his experiments. It was important for the experiments that the dogs were in as normal a state as possible, hence the importance of taking them out on walks to keep them fit and happy. Photograph 1904 Published: [1904]