BAILLON, GUILLAUME DE French physician, studied in Paris, and became physician to the Dauphin, son of Henry IV. He has a place in the history of epidemiology on account of two books posthumously published (1640) on epi demics, in which he revived the Hippocratic doctrine of "epidemic constitutions" which seems to have influenced Sydenham's work. Baillon first described whooping-cough (1578), and he differen tiated between rheumatism and gout, as Hippocrates had done. His works include : Definitionur medicinalium Tiber (1639), a glossary of Hippocratic terms; Consilia ; treatises on gynaecology (1643), gout and calculus (1643) and two books on epidemics and ephemeral diseases (1640). His name is also spelt Baillou.