Why the World Needs Protists!1

Abstract In this brief review, literature references are given to researches—involving diverse species of protists—that support the author's firm conviction that the biological world of today absolutely requires the presence of numerous of these generally small and unicelled organisms if it is to survive. Examples supplied come from areas within the field of protistology sensu lato as widely separated as basic phycological research on photosynthesis and protozoological/medical/biomedical investigations on malaria and other pathogens of human beings. Emphasis is primarily on the most relevant works of the past 10–15 years, although historically highly significant papers of older vintage require at least indirect—and occasionally direct—citation.