PLANT-AUTOGRAPHS—BOSE. 437 
The velocity of excitatory impulse in the plant is slower than 
those of higher, but quicker than those of lower animals. The speed 
of the impulse is, however, subject to variation under different 
conditions. One significant result that came out was that while a 
plant carefully protected under glass from outside blows looked 
sleek and flourishing, yet as a complete and perfect organism it 
proved to be a failure. Its conducting power was found atrophied 
or paralyzed. But when a succession of blows rained on this effete 
and bloated specimen, the stimulus canalized its own path of con- 
duction and it became more alert and responsive, and its nervous 
impulses became very much quickened. 
INFLUENCE OF TEMPERATURE ON VELOCITY. 
A decisive experiment to discriminate between the theories of 
mechanical and nervous transmissions consists in the determination 
of the effect of 
temperature 
on the speed of 
transmission. 
Temperature 
has no effect 
on mechanical 
propagation, 
whereas a mod- 
erate varila- 
tion of it pro- 
foundly affects Fi. 14.—Bffect of rising temperature in enhancing velocity of transmission. 
nervous trans- The three records from below upwards are for temperatures 22° C., 28° C., 
ae. The and 31° C., respectively. 
result given in figure 14 is quite conclusive as regards the excitatory 
character of the impulse in plants. It is seen that with rising tem- 
perature the time required for transmission through the same dis- 
tance is continuously reduced. In the present case the velocity is seen 
to be more than doubled by a rise of temperature through 9°. 
The converse experiment is to subject a portion of conducting 
petiole to the action of cold. This retards the speed of conduction. 
Excessive cold temporarily abolishes the conducting power. 
we be eee we bs ee Selle 
INDUCED PARALYSIS AND ITS CURE BY ELECTRIC TREATMENT. 
As an aftereffect of the application of intense cold, the conducting 
power remains paralyzed for a considerable length of time. It is 
a very interesting and suggestive fact that I have been able to 
restore the conducting power quickly by subjecting the paralyzed 
portion of the plant to a measured and moderate dose of electric 
shock. The application of too strong an intensity is, however, very 
detrimental. 
