PLANT-AUTOGRAPHS—BOSE. 423 
the latent period. In the plant is there any definite period which 
elapses between the incident blow and the responsive twitch? Does 
this latent period undergo any variation as in the animal, with 
external conditions? Is it possible to make the plant itself write 
down this excessively minute time interval ? 
Next, is the plant excited by various irritants which also excite 
the animal? If so, at what rate does the excitatory impulse travel 
in the plant? Under what favorable circumstances is this rate of 
transmission enhanced, and under what other circumstances is it 
retarded or arrested? Is it possible to make the plant itself record 
this rate and its variation? Is there any resemblance between the 
nervous impulse in the animal and the excitatory impulse in the 
plant ? 
The characteristic effects of various drugs are well known in the 
case of the animal. Is the plant similarly susceptible to their action ? 
Will the effect of poison change with the dose? Is it possible to 
counteract the effect of one poison by means of another ? 
In the animal there are certain automatically pulsating tissues 
like the heart. Are there any such spontaneously beating tissues ih 
the plant? If so, are the pulsations in the animal and the plant 
affected by external conditions in a similar manner? What is the 
real meaning of spontaneity ? 
Growth furnishes us with another example of automatism. The 
rate of growth in a plant is far below anything we can directly per- 
ceive. How, then, is this growthto be magnified so as to be rendered 
instantly measureable? What are the variations in this infinitesimal 
erowth under external stimulus of light and shock of electric current ? 
What changes are induced by giving or withholding food? What 
are the conditions which stimulate or retard growth ? 
And, lastly, when by the blow of death life itself is finally extin- 
cuished, will it be possible to detect the critical moment? And does 
the plant then exert itself to make one overwhelming reply, after 
which response ceases altogether ? 
PLANT SCRIPT. 
We shall first take up the question of recording response of a plant 
like Mimosa. Here, at the joint of the leaf, there is a cushion-like 
mass of tissue known as the pulvinus. This serves as the motile 
apparatus. The swollen mass on the lower side is very conspicuous. 
Under excitation, the parenchyma in this more effective lower half 
undergoes contraction, in consequence of which there is a fall of the 
leaf. This sudden movement constitutes the mechanical response of 
the leaf to the impinging stimulus, just as the contractile movement 
of a muscle in similar circumstances forms its characteristic mechanical 
response. For obtaining a record, the leaf of Mimosa is attached to 
