The evolution of screening

Botany is usually considered to be the gentlest of sciences with botanists being regarded as people who study relatively safe specimens, compared with , for example, anthropologists or microbiologists. However, botanists have their moments, particularly when collecting new species. The great botanist s of the eighteenth and nineteenth centuries risked their lives in collecti ng and bringing back species, which we now take for granted, and Robert Bro wn was one of these adventurers, a young Scot who accompanied Sir Joseph Ba nks to New Holland. It was not, however, for his adventurous lifestyle that Brown is remembered but for his startling observation of the movements of pollen grains on a m icroscope slide. He noted that the pollen grains were in perpetual agitated motion, without purpose or direction but full of energy. This motion, call ed Brownian motion, arises from the movement of molecules, and Brownian mot ion is the term that has been applied to much of healthcare, including many screening programmes, which have in the past been marked more by the amoun t of energy and activity than by a clear sense of direction or positive ach ievement. Copyright (C) 2001 John Wiley & Sons, Ltd.