Gerhard Hansen: discoverer of the organism of leprosy.

This year marks the hundredth anniversary of the death, on 12 February 1912, of the Norwegian leprologist, Gerhard Hansen, who was the first to describe the Mycobacterium leprae (Hansen's bacillus). It was, in fact, only the second specific disease-causing organism to be discovered, the first being the bacillus of anthrax.

Sir Samuel Wilks (1824-1911): brilliant observer who 'rediscovered' Hodgkin's disease.

Guy's Hospital and its medical school rejoiced in a remarkable group of physicians in the 19th century. These included Richard Bright, a pioneer in the study of chronic nephritis, Thomas Addison, who described two diseases that bear his name (Addison's disease of the suprarenals and Addison's, or pernicious, anaemia), Thomas Hodgkin, who gave the first clear account of lymphadenoma and Sir William Gull, who documented myxoedema, its relationship to the thyroid and its resemblance to cretinism in children.

Matthew Baillie: pioneer of systematic pathology.

This year is the 250th anniversary of the birth of Matthew Baillie, whose textbook Morbid Anatomy of the Human Body, published in 1793, and its accompanying atlas, published 6 years later, constituted the first textbook which dealt exclusively with system-based pathology. This adopted a new and convenient method of describing pathology according to the organs involved rather than according to symptoms, as Giovanni Morgagni (1682-1771) of Padua had adopted in his De Sedibus et Causis Morborum (On the sites and causes of disease). This, published in 1760, was rightly regarded as the first textbook which correlated symptoms in life with the appearance of the viscera at autopsy.