Mast, Samuel Ottmar

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(b. Ann Arbor, Michigan, 3 October 1871; d. Baltimore, Maryland, 3 February 1947)


Mast attended elementary school in his home state and received a teaching certificate from the State Normal College in Ypsilanti, Michigan, in 1897. He received a B.Sc. from the University of Michigan in 1899, and in 1906 he obtained his Ph.D. in zoology from Harvard. After graduation from Michigan Mast started an uninterrupted teaching career, which lasted forty-three years. From 1899 to 1908 he was professor of biology an botany at Hope College, Holland, Michigan, and then associate Professor of biology and professor of botany at Goucher College, Baltimore, Maryland, where he remained until 1911. He then joined the faculty of Johns Hopkins University and became the director of the zoological laboratory in 1938, when Jennings retired. Mast published his book Light and the Behavior of Organisms in 1911, and most of his later research was on the reactions of lower organism to stimuli, especially light. His contractile-hydraulic theory of amoeboid movement, proposed in 1926, continue to be basic in the explanation of this phenomenon. His careful study of the metabolism of the colorless in the flagellate Chilomonas paramecium (1933), showing its ability to synthesize organic compounds in the dark, is also a classic in the field.

During his long working life, Mast published almost 200 papers and books. Besides being a member of many scientific societies, he was awarded the Cartwright Prize by Columbia University in 1909. The State Normal College at Ypsilanti awarded him an honorary M.Pd. in 1912, and the University of Michigan the Sc. D. in 1941, a year before he retired.


I. Original Works. Among Mast’s important works are “Structure, Movement, Locomotion and Stimulation in Amoeba,” in Journal of Morphology, 4 (1926), 347–425, written with D. M. Pace; and “Synthesis From Inorganic Compounds of Starch, Fat, Proteins and Protoplasm in the Colorless Animal, Chilomonas paramecium,” in Protoplasma, 202 (1933), 326–358.

II. Secondary Literature. See D. H. Wenrich, “Some American Pioneers in Protozoology,” in Journal of Protozoology,3 (1956), 17; and the obituary notice by C. G. Wilber, “Samuel O. Mast (1871–1947),” in Transactions of the American Microscopical Society67 (1948), 82–83.

Enrique BeltrÁn