This is an unabridged reprint of the Columbia University Biological Series edition. Chapter titles are ...(1) Historical Introduction ...(2) General ...(3) The Sarcodina ...(4) The Mastigophora ...(5) The Sporozoa ...(6) The Infusoria ...(7) Sexual Phenomena in the Protozoa ...(8) Special Morphology of the Protozoan Nucleus ...(9) Some Problems in the Physiology of the Protozoa.