Chapter II: Part III: Tropism in Plants

XXII.--THE BALANCED CRESCOGRAPH.
PAGE.
Principle of the Method of Balance--Compensating movement--
Growth-scale--Sensitiveness of the Crescographic Balance--
Effect of CO_{2}--Effect of anæsthetics 255

XXIII.--ON TROPIC MOVEMENTS.

Complexity of the problem--Contradictory nature of
responses--Two classes of tropic responses--Longitudinal
transmission of effect of stimulus--Transverse transmission
of effect of stimulus--Modification of tropic curvature by
conducting power of tissues and differential excitability
of the organ 268

XXIV.--TROPIC CURVATURE WITH LONGITUDINAL TRANSMISSION OF
EFFECT OF STIMULUS.

Dual impulses, positive and negative, caused by stimulus--
Direct and Indirect stimulus--Tropic effect of Indirect
stimulation 271

XXV.--TROPIC CURVATURE WITH TRANSVERSE TRANSMISSION OF EFFECT
OF STIMULUS.

Turgor variation under transverse transmission of
stimulus-effect--Tropic responses of pulvinated and growing
organs to unilateral stimulation--Direct unilateral
stimulation--Indirect unilateral stimulation--Difference of
effects induced by Direct and Indirect stimulation--Laws of
tropic curvature 279

XXVI.--MECHANOTROPISM: TWINING OF TENDRILS.

Anomalies of mechanotropism--Effects of indirect and direct
electric stimulation on growth of tendril--Effect of direct
and indirect mechanical stimulus--Immediate and after-effect
of stimulus--Inhibitory action of stimulus--Response of
less excitable side of the tendril--Relative intensities
of responses of upper and under sides of tendril of
_Passiflora_--Negative curvature of tendril 288

XXVII.--ON GALVANOTROPISM.

Polar effects of electric current on growth--Effect of anode
and cathode on growth 301

XXVIII.--ON THERMONASTIC PHENOMENA.

Effect of temperature--Different thermonastic organs--Two
types of response: Positive and Negative--Effect of rise of
temperature and of stimulus on thermonastic organs--Law of
thermonastic reaction 305

XXIX.--ON PHOTOTROPISM.

Complexity of problem of phototropic reaction--Action of
light--Positive phototropic curvature of pulvinated
organs--Positive phototropic curvature of growing
organs--Phenomenon of recovery--Immediate and after-effect
of light on growth--Latent period of phototropic reaction--
Growth variation induced by flash of light from a single
spark--Maximum positive curvature under continued action of
light 313

XXX.--DIA-PHOTOTROPISM AND NEGATIVE PHOTOTROPISM.

Differential excitability of two halves of pulvinus of
_Mimosa_--Transformation of positive to negative
curvature--Tropic effect under sunlight--Negative
phototropism of shoot and root 328

XXXI.--RELATION BETWEEN THE QUANTITY OF LIGHT AND THE INDUCED
PHOTOTROPIC CURVATURE.

Effect of increasing intensity of light on pulvinated and
growing organs--Effect of increasing angle--Effect of
duration of exposure 338

XXXII.--THE PHOTOTROPIC CURVE AND ITS CHARACTERISTICS.

Summation of stimulus--General consideration--The general
characteristic curve--Characteristics of simple phototropic
curve--Variation of susceptibility for excitation in
different parts of the curve--Effect of sub-minimal
stimulus--The complete phototropic curves of pulvinated
and growing organs--Limitation of Weber's law 346

XXXIII.--TRANSMITTED EFFECT OF PHOTIC STIMULATION.

Effect of light applied on tip of Setaria--Response of
growing region to unilateral stimulus--Effect of
simultaneous stimulation of the tip and the hypocotyl--
Algebraical summation of effects of direct and indirect
stimuli 362

XXXIV.--ON PHOTONASTIC CURVATURES.

Phototropic response of anisotropic organs--Positive
para-heliotropism--Negative para-heliotropism--Responses
of pulvinated and growing organs to light 378

XXXV.--EFFECT OF TEMPERATURE ON PHOTOTROPIC CURVATURE.

Effect of temperature on excitability--Effect of temperature
on conduction--Phototropic response of tendrils--Seasonal
variation of phototropic curvature--Antagonistic effects of
light and of rise of temperature 388

XXXVI.--ON PHOTOTROPIC TORSION.

Torsional response to light--Effect of different modes of
lateral stimulation--Effect of differential excitability on
the direction of torsion--Laws of torsional response--
Complex torsion under light--Advantages of the Method of
Torsional Response--The Torsional Balance--Determination
of the direction of stimulus 397

XXXVII.--RADIO-THERMOTROPISM.

Effect of infra-red radiation--Positive radio-thermotropism--
Dia-radio-thermotropism--Negative radio-thermotropism 410

XXXVIII.--RESPONSE OF PLANTS TO WIRELESS STIMULATION.

Effects of different rays of spectrum on growth--The wireless
system--Mechanical and electrical responses of _Mimosa_ to
Hertzian waves--Effect of wireless stimulation on growth of
plants 416

XXXIX.--GEOTROPISM.

Direction of the stimulus of gravity--The Geotropic
Recorder--Determination of the character of geotropic
reaction--Theory of statoliths--Determination of the latent
period--The complete geotropic curve--Determination of
effective direction of stimulus of gravity--Algebraical
summation of effects of geotropic and photic stimulus--
Analogy between the effects of stimulus of light and of
gravity--Relation between the directive angle and geotropic
reaction--Differential geotropic excitability 425

XL.--GEO-ELECTRIC RESPONSE OF SHOOT.

Electric response to direct and indirect stimulation--
Experimental arrangement for obtaining geo-electric
response--Geo-electric response of the upper and lower
sides of the organ--Method of Axial Rotation--Characteristics
of geo-electric response--Physiological character of
geo-electric response--Effect of differential excitability
of the organ--Law determining the relation between angle
of inclination and geotropic effect--Method of Vertical
Rotation--Electric response through an entire cycle--
Relation between angle of vertical rotation and intensity
of geo-tropic reaction 442

XLI.--MECHANICAL AND ELECTRICAL RESPONSE OF ROOT TO VARIOUS
STIMULI.

Mechanical and electrical response to Direct stimulation--
Mechanical and electrical response to Indirect stimulation--
Effect of unilateral stimulation applied at the root-tip 461

XLII.--GEO-ELECTRIC RESPONSE OF ROOT.

Geo-electric response of the root-tip--Electric response in
the growing region of root--Differential effect between the
tip and the growing region--Geo-perception at the root-tip 467

XLIII.--LOCALISATION OF GEO-PERCEPTIVE LAYER BY MEANS OF THE
ELECTRIC PROBE.

Principle of the method of electric exploration--The
Electric Probe--Electric exploration of the geo-perceptive
layer--Geo-electric reaction at different depths of
tissues--Microscopical examination of the maximally excited
layer--Influence of season on geo-electric response--Tests
of insensitive specimens--Reaction at lower side of the
organ--The Method of Transverse Perforation 478

XLIV.--ON GEOTROPIC TORSION.

Arrangement for torsional response--Algebraical summation of
geotropic, and phototropic effects--Balance of geotropic by
phototropic action--Comparative balancing effects of white
and red lights--Effect of coal gas on photo-geotropic balance 503

XLV.--ON THERMO-GEOTROPISM.

Necessary conditions for geotropic curvature--Modifying
influence of temperature on geotropic curvature--Magnetic
analogue--Tropic equilibrium under varying intensities of
stimulus--Effect of variation of temperature on geotropic
torsion--Variation of apo-geotropic curvature under thermal
change--Effect of variation of temperature on dia-geotropic
equilibrium 509