. Effects of the rays of radium on plants . Fig. 63. Fig. 64. Experiment 93. Curvatures of Root-Tips of Lupinus albus toward a sealed Glass Tube of Radium Bromide in Water (figure 64), and in a nutrient Solution (figure 63). suspended by threads so as to lie horizontally in the water with the salt distributed evenly over the bottom of the tube. The latter was placed in numerous trials at distances of from 2-25 mm. from the tips of the roots. At a distance of 25 mm. no effects were observed, but at distances of from 10 to 2 mm. curvatures took place toward the tube. Photographs of two of these
. Effects of the rays of radium on plants . Fig. 63. Fig. 64. Experiment 93. Curvatures of Root-Tips of Lupinus albus toward a sealed Glass Tube of Radium Bromide in Water (figure 64), and in a nutrient Solution (figure 63). suspended by threads so as to lie horizontally in the water with the salt distributed evenly over the bottom of the tube. The latter was placed in numerous trials at distances of from 2-25 mm. from the tips of the roots. At a distance of 25 mm. no effects were observed, but at distances of from 10 to 2 mm. curvatures took place toward the tube. Photographs of two of these trials are shown in figures (iT^ and 64. The results in figure 63 are quite similar to the electro- tropic curvatures figured by Plowman. In this instance the tap- water was replaced by a nutrient solution made according to direc- tions given on page 85 of MacDougal's Elementary Plant Physiology. No constant differences were observed between the curvatures in tap-water and culture solution. ever, in the following year, stated that the electrical conductivity of water was not altered by exposure for a short period, but was slightly increased by exposure for as long as two days. The question is referred to further in Chapter XIX.
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