Osler's influence on haematology.

Osler's influence in haematology was twofold: as an original observer both in the laboratory and the ward, and his encouragement of the establishment of clinical laboratories with the consequent development of clinical and laboratory haematologists. In 1870, when Osler entered McGill Medical School at the age of 21, he was already an experienced microscopist from his school days, but now his interest shifted from pond life to parasites and clinical microscopy. His post-graduate year with Burdon-Sanderson was to have been a study of leucocyte function, but instead came his research on platelets, continued and expanded when he returned to Montreal in 1874, together with much of his laboratory haematology--his comprehensive studies of pernicious anaemia and work on leukaemia, Hodgkin's disease etc. The move to Philadelphia in 1884 saw the establishment of a clinical laboratory, work on malaria, arsenic in anaemia and the blood disease chapter for Pepper's System. At Baltimore he had a rewarding clinical microscopy department, distinct from Welch's Institute, and this is the period, continued at Oxford, of Osler's accounts of clinical syndromes--polycythaemia, telangiectasia, mastocytosis and 'splenic anaemia'.