. Bulletin. Agriculture; Agriculture -- Arizona. CAUSE AND NATURE OF CROWN-GALL 51 never observed cells in the process of nuclear division when the Plasmodium was evident, although karyokinesis is frequent in adjacent ones. It may be inferred that invisible cytoplasmic portions of the parasite penetrate the cell walls and pass through adjacent cells to some distance from those in which the Plas- modium is first visible, and that they create a stimulus inducing accelerated growth and cell division. Such a stimulus might also be produced by the effect of metabolic products of the Fig.
. Bulletin. Agriculture; Agriculture -- Arizona. CAUSE AND NATURE OF CROWN-GALL 51 never observed cells in the process of nuclear division when the Plasmodium was evident, although karyokinesis is frequent in adjacent ones. It may be inferred that invisible cytoplasmic portions of the parasite penetrate the cell walls and pass through adjacent cells to some distance from those in which the Plas- modium is first visible, and that they create a stimulus inducing accelerated growth and cell division. Such a stimulus might also be produced by the effect of metabolic products of the Fig. 26.—Multiuuclear cells from the meristematic tissue of a young gall. (Magnified same as scale ; scale = 10 ) Karyokinesis frequently occurs in large parenchyma cells, even when poorly supplied with plasmic contents, if they be adjacent to diseased tissue (see Plate), and it is presumed that karyokinesis may occur in any normal parenchyma cell and a new center of growing tissue originate under the stimulus in- duced by the parasite. In such cases nuclear division frequently occurs without the formation of a cell plate, and as a result multiuuclear cells are frequent (Fig. 26). Such cells are usually later divided by the formation of Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original University of Arizona. Agricultural Experiment Station. Tucson : Agricultural Experiment Station, University of Arizona
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