Word: physarum
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Dates: during 1937-1937
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Slime molds are among the most primitive of living things. Six years ago one of them, a golden yellow mold long known to botanists as Physarum polycephalum, was successfully cultured indoors by Dr. Frank Leslie Howard of Rhode Island State College. Later he turned his molds and his methods over to Dr. Seifriz. Ever since his student days at Johns Hopkins and in England, Germany, Switzerland and France, William Seifriz had hankered for generous supplies of "naked proto-plasm." Physarum polycephalum filled the bill. In a lyrical moment Dr. Seifriz called it a "great big glorious handful...
...Since Physarum produces "fruits" at intervals averaging 14 days (at the end of which it turns into hard, seedlike cells), it is formally classified as a plant. Yet the new little fruits, bundles of protoplasm, have powers of locomotion like an animal. They move by the classical method of protoplasmic streaming-protruding part of their body, pulling the rest after the protrusion...
This protoplasmic streaming interests Dr. Seifriz immensely. The movements of Physarum show a definite pulse, not unlike that of a beating heart. With inadequate motion-picture equipment at Philadelphia, he was not able to see this living rhythm until he went to studv at the Pasteur Institute in France where films had been made and slowed down 100 times. The Physarum pulse was seen to have a period of about 45 seconds. Dr. Seifriz rejects the older theories attributing protoplasmic movement to surface tension, electric potentials, etc. "I ask the reader," he wrote recently in Science, "merely to admit that...
Last summer Dr. Seifriz overwhelmed with gratitude his friends at the Pasteur Institute by taking across the Atlantic a bowlful of Physarum polycephalum. Well might they be pleased with such a thing to study for this mold in many ways is the lowest visible form of life. Bacteria are smaller than the mold cells but their claim to superlative primitiveness is "questionable" and they are harder to study. Amebas are also simple bits of protoplasm, but they have something which Physarum lacks-a contractile vacuole (cavity) which squirts body fluids to the outside...
...primitive Physarum has extraordinary qualities of high resistance to X-ray bombardments and emanations from radium, it resembles the cells of stubborn cancers called fibrosarcomas...