It is more than a hundred years since Magendie (1827) found that fluid fat circulating in the blood stream might obstruct a vessel. Perhaps because of the apparent simplicity of this mechanical obstruction he did little experimental work with circulating fat and no large recognition was given to his discovery. In 1865 Virchow injected oil into the neck vein of a dog and produced a fatal fat embolism, which was accompanied by acute pulmonary edema. A few years later Riedel1produced extensive fat embolism in the lungs by oil, which had been injected into an artery and which had in the meantime passed through other organs. Scriba2demonstrated that droplets of fat could pass through other organs and the lungs as well, without difficulty in certain instances; previously a patent foramen ovale had been considered essential to the passage of embolic fat from the lesser to the greater