UNRAVELING DROPSY - FROM MALPIGHI,MARCELLO DISCOVERY OF THE CAPILLARIES (1661) TO HALES,STEPHEN PRODUCTION OF EDEMA IN AN EXPERIMENTAL-MODEL (1733)

A modern understanding of oedema formation traditionally begins with S tarling's description in 1898 of hydrostatic and oncotic forces acting on the capillary membrane. Clearly, hypotheses of oedema formation pr edating the knowledge of the existence of capillaries must have been i ncomplete. Marcello Malpighi first described capillaries in 1661, but although he displayed a good grasp of the principles of the Harveian c irculation and believed that oedema fluid (the clinical entity dropsy) was derived from the blood rather than the tissues, we have found no evidence that he realised the central role played by his discovery. Ho wever, only 60 years later, Stephen Hales' Haemastaticks reveals the c reation of an experimental model for dropsy which led him towards an u nderstanding of oedema formation not far behind Starling.