ocr: Protozoa even the simplest forms in nature are often quite complex and very beautiful. Protozoa ares single-celled, microscopic organisms formerly classified as animals, the most broadly known of which are probably amoebae and paramecia. New information gained by the use of electron micro- scopes and techniques of molecular biology has changed our ideas on how to classify this ancient group of eukaryotic, or complex-celled, organisms. They are now assigned to a separate 215