Dr Edward Jenner (1749-1823) of Berkeley, and vaccination against smallpox.

Correspondence to: Professor P M Dunn. Edward Jenner was born on 17 May 1749, the eighth child of the Reverend Stephen Jenner, vicar of Berkeley in the county of Gloucestershire. Both his parents died when he was 5 and he was then looked after by his eldest brother. Educated at Wotton-underEdge and Cirencester, at the age of 13 he was apprenticed for seven years to Daniel Ludlow, a surgeon of Sodbury near Bristol.' In 1770 he travelled to London to become a house pupil of John Hunter and a student at St George's hospital. Three years later, resisting the suggestion that he practise in London, Jenner returned to Berkeley to become a country physician: perhaps because he was a keen naturalist. Besides being both curious and observant, he kept meticulous notes and possessed a happy combination of common sense and scientific logic. Spurred on by John Hunter with whom he had developed a warm friendship and who wrote, 'Why think? Why not try the experiment?', Jenner studied such subjects as the temperature of hibernating hedgehogs, the life history of eels, and the migration of birds. His best known observations were on the cuckoo. This bird was known to lay its eggs in the nests of other birds, particularly the hedgesparrow, and to depend on the foster parents to hatch and feed its chicks. Philosophers since the days of Aristotle had puzzled as to how the foster parent's own chicks came to be ejected from the nest and left to die. Jenner discovered that the cuckoo chick was itselfresponsible and demonstrated by dissection that the latter had a hollow on its back that enabled it to obtain a good purchase. In one instance he recorded observing two cuckoo hatchlings in one nest. He wrote: 'The contest was very remarkable. The combatants alternately appeared to have the advantage, as each carried the other several times to the top of the nest, and then sunk down again, oppressed by the weight of its burden; till at length, after various efforts, the strongest prevailed'. After his findings had been presented to the Royal Society in 1788, he was elected FRS.2 Jenner was a conscientious and successful doctor, a vigorous countryman, and adept at social gatherings. He took pride in his appearance, enjoyed good food, singing and playing the flute and the fiddle, and he wrote poetry about the countryside. In 1788 he married Catherine Kingscote and the following year Dr Edward J7enner in 1801.