THE EVER-ACTIVE PLANT 133 
world, animal as well as vegetable, depends.* 
Utilizing the energy which comes through space from 
the sun, it builds up organic compounds; from the 
energy thus stored comes all the varied life and vital 
movement which fill our world—the opening of 
flowers, the hum of insects, the march of armies, and 
our own restless thought; while its work in the distant 
past, laid by in coal and oil, warms our houses and 
drives our trains, factories, and steamships. 
The work of the living chlorophyll accomplished, 
the food materials produced by its agency are sent by 
the pipe-system to all parts of the plant, for present 
use, or to be stored in root, stem, or leaf for future 
requirements. 
Nor is our plant the passive, motionless thing that 
it may appear to be in comparison with animals and 
their larger movements. Active motion, local and 
general, though usually of relatively small amount, 
accompanies all plant-growth. Throughout root, 
stem, leaf, and flower transference of material is going 
forward vigorously. The root hairs and stomata are 
working at high pressure; the chlorophyll never 
ceases its activities while daylight lasts. Externally, 
the growing branches, leaves, and flowers also display 
incessant movement, sweeping the air in small circles, 
or in the case of climbing plants in curves of con- 
siderable amplitude. Alterations of illumination or 
of temperature produce other movements—bendings 
towards or away from light, the drooping of leaves 
and closing of flowers at nightfall, and so on. 
* To beaccurate, certain groups of Bacteria, the lowest forms of 
organized life, must be excluded. They appear capable of building 
up their bodies directly out of inorganic substances, 
