viii
CONTENTS
CHAPTER IV
DETERMINATION OF VELOCITY OF ASCENT BY MECHANICAL RESPONSE
PAGE
Difference of velocity of ascent in cut and rooted specimens—Influence of the previous history of the plant—The Duplex
Method—The effect of drought—The effect of physiological anisotropy induced by stimulus—Determination of velocity in the reverse direction—Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
40 | |
CHAPTER V
EFFECT OF PHYSIOLOGICAL VARIATIONS ON ASCENT OF SAP
The Potograph—Effect of physiological agents in modification of ascent—Effect of diminished internal pressure—Effect of stimulus—Modifying influence of tonic condition—Effect of variation of temperature on ascent and on growth—The critical thermometric minimum — Drooping of leaves during frost—Phenomenon
of accommodation—Effect of anæsthetics—Effect of poison—Method of exudation—Strasburger's experiments—Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
51 | |
CHAPTER VI
TRANSPIRATION
Physical evaporation and physiological excretion—Isolation of absorbing, conducting, and excreting organs—The Bubbling Method for measurement of transpiration—Comparison of transpiring activity of different species of plants—Ratio of transpiration from upper and lower surfaces of leaves—Determination of transpiration from a single stoma—Transpiration in the absence of evaporation—The rôle of evaporation—Physiological continuity in stem and leaf—Crucial tests of physiological activity underlying transpiration—Effect of variation of temperature—Effects of sub minimal and maximal stimulus—Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
81 | |
CHAPTER VII
VARIATION OF TRANSPIRATION UNDER PHYSIOLOGICAL CHANGE
The Micro-Transpirograph—Effect of diminution of turgor on transpiration—Effect of stimulus—Opposite effects of stimulation of upper and lower surfaces of leaf—Effect of high frequency Tesla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
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