Physiologie. 
163 
especially on the conception of Stimulus, and much of the Inter¬ 
pretation of response depends upon this. A paragraph may be quoted 
(p. VIII). “From the plausible analogy the firing off a gun.it 
“has been customary to suppose that all responses to Stimulus must 
“be of the nature of an explosive Chemical Charge accompanied by 
“an inevitable run-down of energy. This supposition however over- 
“looks the obvious fact that the plant is not consumed by the inces- 
“sant and multifarious Stimuli of its environment. Rather, as we all 
“know, it is the energy of the environment which is the agent that 
“fashions the microscopic embryo into the gigantic banyan-tree. 
“And it is clear that, for this to be possible, the energy contributed 
“by the blow of external Stimulus must have been largely conserved.” 
The wide distribution of electrical responsiveness not only in 
sensitive plants but throughout all Organs of all plants is well esta- 
blished and detailed comparison is made with the Simplex phenomena 
of the responses of animal tissues. In all 321 experiments are descri- 
bed in the course of the book and there is a useful special index 
to them. 
Some idea of the contents of this book may be given by a short 
summar}^. 
The electromotive response of plants to different forms of Stimu¬ 
lation, such as sudden rise of temperature, pressure, torsion, cutting, 
Chemicals, light and electric currents, the mechanical and electrical 
responses thereto. 
The application of quantitative Stimulus and the relation of 
response to Stimulus. 
Positive and negative turgidity variations of plant Organs upon 
Stimulation and the electrical indications of these; differentiation 
between transmitted wave of hydrostatic tension and transmission 
of wave of true excitation. 
External Stimulus and its relation to internal energy: effective 
Stimulation induces contraction and galvanometric negativity; increase 
of internal energy induces expansion and galvanometric positivity. 
Relation of tonicity to form of response; all types of response 
and fatigue may be obtained from any organ, according to condition. 
Detection of anisotropy of condition by electric response. The 
natural current in anisotropic organs from less to more excitable 
part: variations of current by Stimulation. 
Current of injury and negative Variation; current of death, 
response by positive Variation. Distribution of electric potential in 
plant tissue along a line from living to dead area. 
The Death point; its physical and electrical signs. By various 
methods and various plants the death point was always 59°—60° C. 
Multiple and autonomous electrical response by part of energy 
of impinging Stimulus becoming latent for subsequent expression. 
Comparison of leaf as electrical organ with those of animals. 
Theory of electric organs. 
Response of animal and vegetable skins and other corresponding 
parts. Parallelism between responsive reaction of root and digestive 
organs. Ascent of water and vital physiological process, fundamen- 
tally excitatory in character. 
Responses to Stimulus of light all reducible to reactions of con¬ 
traction or expansion. Electric response of geotropically stimulated 
organs, phvsically restrained. 
Determination of velocity of transmission of excitation in plant 
tissues; This protoplasmic and not hydromechanical. Velocity; in 
