Pellicular fragments were isolated from ethanol-fixed cells of the holotrichous ciliate Tetrahymena pyriformis by the action of digitonin. The isolated pellicles were further fragmented and the basal bodies of the cilia isolated from them by three methods. The preparations, examined in the electron microscope as embedded sections or negatively stained samples, consisted mainly of somewhat deformed pellicular material, the bulk of which was basal body. DNA was determined by the diphenylamine method and by reaction with DNase, and RNA, by the orcinol method. Nucleic acids were isolated by phenol extraction and analyzed spectrophotometrically and by reaction with RNase. The assays indicated 1.2 to 2.6 per cent RNA, similar to previously published work, but only 0.0 to 1.0 per cent DNA, near enough the sensitivity limits to render the presence of DNA in the preparations uncertain. Although the isolation procedure removed nuclear contents and ribosomes, the nucleic acids could still be a residual contaminant bound to the pellicle during the isolation. Hypotheses of basal body self-duplication, moreover, can be constructed both with and without nucleic acids.

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