Science: Glorious Handful

SCIENCE

Dr. William Seifriz of the University of Pennsylvania lives a quiet bachelor’s life in Chester Springs, collects old Italian bronze and French porcelain, permits no telephone in his house. At his ground-floor laboratory in Philadelphia he good-humoredly allows an impertinent squirrel to come in by the window, make off with chocolate bars and filter paper. Squirrels, however, are not Dr. Seifriz’ favorite pets. On a far greater favorite of his he last week performed an experiment with extraordinary results.

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 protoplasm is alive, for in so doing, he tacitly grants that it exhibits irritability, in other words, nervous response.”

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.

As 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.

It shows no ill effects when subjected to 12,000 X-ray units, whereas a rat succumbs under 1,000 units. When a radium needle shooting powerful gamma rays is dipped in a dish containing the mold, the protoplasm bundle comes close, hesitates for 24 hours, then embraces the needle for three or four days, finally departs like a child bored with a game. Dr. Seifriz is interested in what might kill such a tough living thing. He has already found that colloidal solutions of gold and silver kill the mold, but that this is not due to colloidal particles but to ions of metal salts. He and his associates are now investigating the effects on Physarum of nitrogen, oxygen, carbon dioxide, carbon monoxide, chlorine, hydrogen, ultraviolet rays.

Last week Dr. Seifriz subjected his mold, which had shown such extraordinary powers of maintaining life, to an attack by ethylene gas. This gas is used as a ripener for citrus fruits, occasionally as an anesthetic for man. Overdoses are deadly. Physarum, however, lived in an ethylene atmosphere for 24 hours without the slightest harm. Only after two or three days in the gas chamber did it begin to dry up, disappear.

Dr. Seifriz. who likes to grapple with fundamentals, is not particularly interested in such side issues as the resemblance between tough Physarum and tough cancer cells, although he is willing to dish out samples of the mold to other investigators for researches of their own. What he himself is looking for is the lowest common denominator of life.