Synopsis Protozoa, simplest in structure, are the most primitive or first animals of nature. They are heterogeneous assemblage of some 50,000 a cellular or single cell organisms possessing typical (eukaryote) membrane bound cellular organelles. These are commensal, mutualistics, and many parasitic species. The great majority of protozoa are microscopic.This work in three volumes provides encyclopaedic information on the phylum Protozoa. General characters and classification and brief description of other important types of the phylum have been dealt with complete, authentic and up-to-date account presented here will prove a dependable source of reference to students, researchers and academics.