Abstract
The introduction of the air-driven ultracentrifuge described by Beams and his associates 1 affords a means of testing the viscosity and relative specific gravity of many cell components. The authors have been able by the use of this ultracentrifuge to establish the fact that the Nissl bodies of rat ganglion represent a definite material in the cell and are not the result of the action of the fixative used on homogeneous cytoplasm; likewise, for the Golgi apparatus in the uterine gland cells of the guinea pig. In general the nuclei of the cells mentioned above usually show a clearly marked separation of the chromatic from non-chromatic materials in such a way to show that the chromatin is the heavier. The details of this work are to be reported elsewhere. McClendon 2 and Yancey 3 have reported the effect on the division rate of centrifuging various species of Paramecium. McClendon has also described some of the nuclear effects of such treatment.
The ultracentrifuge used in this work was obtained from Professor J. W. Beams of the University of Virginia; the 1 1/8 inch rotor was operated by an air pressure of approximately 15 pounds. Paramecium caudatum and P. multimicronucleata were centrifuged in gum solutions of approximately their specific gravity for varying periods. After 10 minutes most of the animals had disintegrated, a few dead organisms remaining intact. These were dumb-bell shaped (length to width ratio varying from 13:1 to 22:1 compared with the normal 4:1 to 5:1) with prominent knobs on either end. The knob on the centrifugal pole consisted of crystals and the macronucleus, that on the other end of lighter materials of unknown nature. The cytopharynx and contractile vacuoles seemed stretched with the pellicle but otherwise normal in position.
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