Prominent among the presidential duties specified in the By-Laws of this Society is the delivery of an address at its annual meeting. Fortunately, at least in my own opinion, no restrictions or indications as to its subject matter have been laid down. Consequently, the presidential addresses made during the period of my association with this Society (now more than 30 years) reflect the diverse interests, concerns and drives of my distinguished predecessors in this high office. Some of them have dealt with purely technical considerations of one or more aspects of tropical disease or of basic or applied research in related fields in which they were masters. Others have stressed the importance of tropical medicine and hygiene in world health and economy, or have summarized its accomplishments in the past, or have even ventured to prognosticate its future.