. Carnegie Institution of Washington publication. 156 Hydration and Growth. It will be seen by reference to the records of growth cited in table 116 that the higher temperature lies above the point at which the most rapid elongation or thickening takes place, a matter which might be due to excessive water-loss or to the action of residual acids at high temperatures. TABLE 117. TABLE 116. Swelling of bean pods. 18° C. 38° C. p. ct. p. ct. Distilled water 2 Citric acid, N. 2 Shrinkage. Swelling of beans. 18° C. 38° Distilled water p. ct. 11 p. ct. Citric acid,
. Carnegie Institution of Washington publication. 156 Hydration and Growth. It will be seen by reference to the records of growth cited in table 116 that the higher temperature lies above the point at which the most rapid elongation or thickening takes place, a matter which might be due to excessive water-loss or to the action of residual acids at high temperatures. TABLE 117. TABLE 116. Swelling of bean pods. 18° C. 38° C. p. ct. p. ct. Distilled water 2 Citric acid, N. 2 Shrinkage. Swelling of beans. 18° C. 38° Distilled water p. ct. 11 p. ct. Citric acid, Beans nearly mature but still in the process of enlargement were removed from green pods, the ends of the cotyledons cut away, and then a slice removing the hypocotyl; the remainder of the cotyledons came away free from the outer coating or mem- brane. The average diameter of trios of such sec- tions was 3 to mm., and their swelling was as given in table 117. The amount of hydration was less at the higher temperature in distilled water, suggesting that the point of maximum imbibition or swelling lies be- low 38° C. In the presence of acid the amount of water absorbed is distinctly less than at 18° C. These data being available, attention may now be profitably turned to the features of enlargement of the pods. Preparations were made by which delicately weighted auxographs recorded the variations in thickness of pods in the stage when about half the final length had been reached. The end of the bearing-lever rested over an enlarging bean, and variation during a week is shown in figure 40. The localization of growth had been previously determined by the well-known expedient of mark- ing a young pod which was in the stage of initial growth of the young beans into four 1-centimeter intervals (fig. 41). Swelling tests had been made FIG. 40.—Arrangement of f ,, •, . ,,. , /, u i -i-tf*\ rn j vertical lever of auxo- of the pods in this stage (table 116). Ten days later t
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