PLANT-AUTOGRAPHS AND THEIR 
REVELATIONS.! 
i answering the questioa whether there is a funda- 
mental unity in the response of plant and animal, 
we have first to find out whether sensitiveness is 
characteristic of only a few plants or whether all 
plants and every organ of every plant is sensitive. 
Then we have to devise apparatus by which visible 
or invisible reactions are detected and_ recorded. 
Having succeeded in this, we have next to survey the 
characteristic reactions in the animal, and observe 
whether phenomena corresponding to these may also 
be discovered in the plant. . 
Thus, when an animal is struck by a blow, it does 
not respond at once. A certain short interval elapses 
between the incidence of the blow and the beginning 
of the reply. This lost time is known as 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 pos- 
sible to make the plant itself write down this exces- 
sively minute time-interval ? 
Next, is the plant excited by various : 
irritants which also excite the animal? a 
If so, at what rate does the excitatory ima) 
coe ia 
impulse travel in the plant? In what | w 
favourable circumstances is this rate of 
transmission. enhanced, and in what ! 
other circumstances is it retarded or 
arrested? Is it possible to make the | 
plant itself record this rate and_ its y) 
variation? Is there any resemblance 
between the excitatory impulse in the 
plant and the nervous impulse in the 
animal ? 
The characteristic effects of various 
drugs are well known in the case of the 
animal. Is the plant similarly suscep- 
tible to their action? Will the effect of 
poison change with the dose? Is it ii 
possible to counteract the effect of one Ao | 
by means of another? ACN 
In the animal there are certain auto- 
matically pulsating tissues like the 
[JULY 23, 1914 
detection and record of the actual response of the 
organism to a questioning shock. By the invention 
of different types of recorders, I have succeeded in 
making the plant itself write an answering script to 
a testing stimulus. Thus the plant attached to the 
recording apparatus is automatically excited by a 
stimulus absolutely constant. In answer to this it 
makes its own responsive records, goes through its 
period of recovery and embarks on the same cycle 
over again, without assistance at any point from the 
observer (Fig. 1). 
The Resonant Recorder, 
In obtaining the actual record of responsive move- 
ments in plants we encounter many serious difficulties. 
In the case of muscle-contraction, the pull exerted is 
considerable and the friction offered by the recording 
surface constitutes no essential difficulty. In the case 
of plants, however, the pull exerted by the motile 
organ is relatively feeble, and in the movement of the 
very small leaflets of Desmodium gyrans or the tele- 
graph plant, for instance, a weight so small as four- 
hundredths of a gram is enough to arrest the pulsa- 
tion of the leaflets. Even in the leaf of Mimosa the 
friction offered is enough to introduce serious errors 
into the amplitude and time-relations of the curve. 
This error could not be removed as long as the writer 
remained in continuous contact with the writing sur- 
face. I was finally able to overcome the difficulty by 
making an intermittent, instead of a continuous con- 
tact. The possibility of this lay in rendering the 
writer tremulous, this being accomplished by an in- 
vention depending on the phenomenon of resonance. 
heart. Are there any such spontaneously Fic, r.—Diagrammatic representation of automatic plant-recorder. Petiole of Mimosa, attached 
beating tissues in the plant? If so, are 
the pulsations in the animal and the 
a similar manner? What is the real 
meaning of spontaneity ? 
Growth furnishes us with another example of auto- 
matism. The rate of growth in a plant is far below 
anything we can directly perceive. How, then, is this 
growth to be magnified so as to be rendered instantly 
measurable? What are the variations in this infini- 
tesimal growth under external stimulus of light and 
shock of electric current? What changes are induced 
by giving or withholding food? What are the con- 
ditions which stimulate or retard growth? 
And, lastly, when by the blow of death life itself is 
finally extinguished, 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. 
The plant is acted upon by storm and sunshine, 
warmth of summer and frost of winter, drought and 
rain. What coercion do they exercise upon it? What 
subtle impress do they leave behind? These internal 
changes are entirely beyond our visual scrutiny. 
I'he possibility of these being revealed to us lies in the 
ats Neca RE Ad at ae delivered at the Royal Institution 
NO. 2334, VOL. 93] 
by thread to one arm of lever L; writing index W traces on smoked glass plate G the 
responsive fall and recovery of leaf. P, primary, and S, secondary, of induction coil. 
E ee Exciting induction shock passes through the plant by electrodes E, E’. A, accumulator. 
plant affected by external conditions in C, clockwork for regulating duration of tetanizing shock. 
completed by plunging rod K dipping into cup of mercury M. 
Primary circuit of coil 
|The principle of my resonant recorder depends on 
_ sympathetic vibration 
_ are exactly tuned, then a note sounded on one will 
If the strings of two violins 
cause the other to vibrate in sympathy. We may 
likewise tune the vibrating writer V, with a reed C 
(Fig. 2). Suppose the reed and the writer are both 
tuned to vibrate a hundred times per second. When 
the reed is sounded the writer will also begin to vibrate 
in sympathy. In consequence of this the writer will 
no longer remain in continuous contact with the 
recording plate, but will deliver a succession of taps 
a hundred times in a second. The record will there- 
fore consist of series of dots, the distance between one 
dot and the next representing one-hundredth part of a 
second. With other recorders it is possible to measure 
still shorter intervals. It will now be understood 
how, by the device of the resonant recorder, we not 
only get rid of the error due to friction, but make 
the record itself measure time as short as may be 
desired. The extraordinary delicacy of this instrument 
will be understood when by its means it is possible to 
record a time-interval as short as the thousandth part 
of the duration of a single beat of the heart. In find- 
