440 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
the records thus obtained I am enabled to say that the automatic 
movements of both plants and animals are guided by laws which are 
identical. ae 
Firstly, when for convenience of experiment we cut off the leaflet, 
its spontaneous movements, like those of the heart, come to a stop. 
But if we now subject the isolated leaflet by means of a fine tube to an 
added internal hydrostatic pressure, its pulsations are renewed and 
continue uninterrupted for a very long time (fig. 16). It is found 
again that the pulsation frequency is increased under the action of 
Fic. 16.—Record of automatic pulsations in Desmodium gyrans. 
warmth and lessened under cold, increased frequency being attended 
by diminution of amplitude and vice versa. Under ether there is a 
temporary arrest, revival being possible when the vapor is blown 
off (fig. 17). More fatal is the effect of chloroform. The most 
extraordinary parallelism, however, lies in the fact thaf those poisons 
which arrest the beat of the heart in a particular way arrest the 
plant pulsation also in a corresponding manner, the arrest produced 
being either at sys- 
tole or diastole, de- 
pending on the char- 
acteristic reaction of 
the poison. Taking 
advantage of the an- 
Fic. 17.—Arrest of pulsation of Desmodium under ether; restoration 3 OL ue : 
of pulsation on blowing off ether. The arrow indicates the time of tagonistic reactions 
application. of specific poisons, I 
have been able to 
revive a poisoned leaflet by the application of another counteracting 
poison. 
Let us now inquire into the causes of these automatic movements, 
so called. In experimenting with certain types of plant tissues 
[ find that an external stimulus gives rise to the same amplitude of 
response, whether the stimulus be feeble or strong. What happens, 
then, to the excess of the incident energy? It is not really lost, 
for these particular plant tissues have the power of storage. In this 
way energy derived in various ways from without—such as light, 
warmth, food, and so on—is constantly being accumulated. When 
a certain point is reached, there is a bubbling overflow, and we call 
this overflow spontaneous movement. Thus what we call automatic 
is really an overflow of what has previously been stored up. When 
this accumulated energy is exhausted, then there is also an end of 
