A neuroscientist might describe a nightmare differently, but an 1810 image by the English engraver Jean Pierre Simon certainly captures the terror. It's one of thousands of medically themed photos and art housed at Wellcome Images, a new gallery from the British biomedical charity the Wellcome Trust.

The site's contemporary collection is the place to search if you want, say, a spectacular photo of dividing cells caught at the moment of parting or an electron micrograph of influenza viruses barging into tracheal cells. To trace changes in medical knowledge and practice, browse the historical collection, whose holdings include rarities such as 15th century Chinese anatomical drawings and a 1920s Soviet propaganda poster on the dangers of typhus. If your intentions are pure (that is, noncommercial), you can download the images free.

Volume 317, Number 5836, Issue of 20 July 2007