The flagellates: historical perspectives
ABSTRACT Although references to flagellates en masse are apparently recorded in biblical and other early texts, the earliest authenticated observations of individual flagellates using a microscope are attributed to Antony van Leeuwenhoek during the second half of the seventeenth century. Leeuwenhoek is credited with seeing, for the first time, an impressive range of free-living and parasitic species. Otto Friderich Muller, in two major works dated 1773 and 1786, is one of the first authors to record flagellates with formal (latinized) descriptions using the system of nomenclature devised by his Scandinavian contemporary Carl von Linnaeus. Many of the taxa that Muller described are still recognized today. The nineteenth century was a time of great expansion in science and witnessed the publication of major works on the protozoa in general, and the flagellates in particular. The monographs of Christian Gottfried Ehrenberg, Felix Dujardin, Fredrich Ritter von Stein, William Saville Kent and Otto Butschli are of particular note. By the end of the nineteenth century an ordered systematics of the protozoa was established and this remained in place, with a few modifications, for the better part of a century. However, from the earliest attempts to devise such a system for the protozoa, our understanding of the evolutionary relationships between the many free-living and parasitic flagellates has remained problematical because of the exceptional degree of paraphyly displayed by these organisms.