Not many weeks have elapsed since The Journal announced the death of Sir Patrick Manson, noted as an authority on tropical medicine. Now a cable from Paris announces the passing of Alphonse Laveran, another famous worker in the same cause, and winner of the Nobel prize in 1907. These two men probably did most to further, if not to found, the new science: Manson, with his demonstration that an insect, the mosquito, was the transmitting agent of filariasis (1879), and Laveran, with his discovery that malarial fever was caused by a parasite (1880). These two apparently simple facts were the solid foundation on which the science of tropical medicine was to be erected. Manson and Laveran broke the ground and opened a road which led Finlay to formulate his yellow fever stegomyia theory; Ross to identify the anopheles as the vector of malarial fever; Reed and the American Army Commission to prove so brilliantly Finlay’s hypothesis, and Gorgas, Cruz, Noguchi and many others to put the new facts to practical uses and to venture further into new fields. French, English, American, Cuban and Japanese investigators have participated and cooperated in a series of epoch-making accomplishments which have benefited every spot in the world.