It is my privilege to speak on behalf of the International Federation of Electron Microscope Societies, to welcome you to this International Congress, which is the Fourth of its kind, but the first to be held under the auspices of the Federation. The first meeting of an international character, with published proceedings, took place in Delft in 1949 and the second in Paris in 1950. These gatherings were organised informally by the active electron microscopists in the respective countries. By 1954, steps had been taken to set up a Joint Commission for Electron Microscopy, as part of the International Council of Scientific Unions, and the London Conference of that year was held under its name. Unfortunately, it soon became clear that the formal structure of a Joint Commission, which must consist primarily of delegates appointed by individual unions of ICSU, was not suited to the needs of an actively developing branch of research, already firmly established in national organizations. After prolonged discussion and negotiation, the Joint Commission was dissolved and its place was taken by a body directly representative of the various national societies for electron microscopy, — the International Federation of Electron Microscope Societies. The governing body of the Federation is the Assembly, consisting of delegates elected by the affiliated societies in proportion to the size of their membership. The Assembly will be meeting on Saturday next, to consider the future programme of meetings, to re-consider its constitution in the light of the experience of the past four years, and elect the President, Secretary and Committee members. Our first President, as you will remember, was Professor von BORRIES. His untimely death in 1956 was a tragic loss to electron microscopy as a whole, and to the Federation in particular.