born April 5, 1801, Tours, France
died April 8, 1860, Rennes
French biologist.
His studies of microscopic animal life frequently found in decaying organic materials led him in 1834 to propose a new group of one-celled animals that he called Rhizopoda . He named the seemingly formless life substance that oozed outward through openings in certain shells sarcode ; later it became known as protoplasm . This work led him in 1835 to argue against Christian Gottfried Ehrenberg 's theory that microscopic organisms have the same organs as higher animals. Dujardin also studied jellyfish, corals, and sea stars; his study of flatworms laid the foundation for the later development of the study of parasites and parasitism.