
e 
THE SENSITIVE PLANT 135 
Behaviour of the leaves at night or on dark days. 
_ On a dark day the leaves of the sensitive plant are 
folded together; or if we take the plant into a poorly 
lighted room, the leaves will close; then if we bring 
it out to the light they will open again. So at night- 
fall the leaves fold together, and the sunlight of the 
following day is necessary before they will open again. 
This teaches us one of the influences which light exerts 
on plants. This plant is very sensitive to contact with 
other objects or to shock; but we see that it is also 
sensitive to light, for the leaves will open in a short 
time when brought into the light. The mimosa is 
called the sensitive plant because it responds so quickly 
to contact stimulus or shock. In reality, however, 
all plants are more or less sensitive, some being more 
so than others. This we can readily see by observing 
_ the relation of other plants to the light. 
