Divisions in Isolated Cells of Palisade Parenchyma of Arachis hypogaea

Abstract

THE exclusive use, up to now, of isolated cells of angiosperms from mechanically separated callus of multicellular origin^1–6 carries the inherent shortcoming that such cells and tissues are patently of artificial origin, environment, and physiology. From every botanical viewpoint, it behoves the investigator of cell morphogenesis to start his experiments with a normal cell. Theoretically, one of the very best starting materials is the mesophyll cell of the angiospermous leaf, the use of which was attempted, unsuccessfully, by Haberlandt⁷ more than 65 years ago. Though Haberlandt reported consistent failure in this early attempt, it is difficult to know the reasons for it, beyond the undeniable fact that axenic conditions were not attained, and indeed, were not considered essential by him. Bobilioff-Preisser⁸ attempted to repeat Haberlandt's trials, with modifications, but had the same failures. Schmucker⁹ reported that the very easily separated mesophyll cells of Macleaya cordata divided, yielding groups of a dozen cells in filter-sterilized grated sap of the same leaf. He published no further observations on it. His results, however, were confirmed by Fiedler¹⁰ (p. 382), who presented no photographs. Kandler¹¹ doubted the foregoing reports and tried the same and other leaves without any success. Once again,, Kohlenbach¹² reported the growth of these isolated mesophyll cells in White's medium with coconut water and 2,4-D. His photomicrograph shows a packet of 6–8 cells which he thought were produced by divisions from a single palisade cell. It appears to us that final proof of divisions in the single isolated mesophyll cell is possible only through a photographic record by time-lapse. This has been provided in the present communication.