Shaking experiments with protozoa

Abstract

DeBary, Hofmeister, Horvath and Meltzer have observed that various species of lower plants (Myxomycetes, Diatoms, Oscillaria and Bacteria) when shaken, are brought to a quiescent condition, for a longer or shorter time or even killed. The present observations were based upon cultures of Paramecium, Euglena, Stylonychia and Spirillum (a species of Schizomycetes). Two methods of shaking were used: (1) Shaking was produced by means of a rotating arm moving in a radius of 25 cm. at a velocity varying from 66 to 83 revolutions per minute and carrying a tube, 6 cm. long within which was a phial holding 2.5 c.c. of the infusion of protozoa. During each revolution, consequently, the protozoa received two shocks from the falling of the smaller phial within the larger one. (2) Following the method of Horvath and adopted by Meltzer in his experiments, a horizontal shaker, making 100 excursions per minute through a path of 8.50 cm. was employed. A 250 c.c. bottle containing 10 c.c. of the infusion and bearing a pycnometer thermometer for registering temperature was fastened in the machine and another bottle similarly equipped was placed near as a check. The animals were shaken for from one to twenty-four hours.