72 
If we wish to see these flowers in perfection, we 
must choose for our woodland excursion a bright, un- 
clouded day; for tbe Wood Aneraone is a natural 
barometer, closing its petals at the approach of rain. 
It is also one of those plants 
“ Which shrinking from the chilly night 
Droop and shut up, but with fair morning’s touch 
Rise on their stems, ail open and upright.” 
How curious is this function of sleep both in the 
leaves and flowers of plants. It dépends upon a 
spécial law of nature, subject in some degree to the 
effects of light and heat; tbe former appears to be 
the chief stimulus in regulating the expansion of the 
blossom, though neither can be regarded as the first 
cause of this phenomenon. # “ When the sensitive- 
plants are confined in a dark room, their leaflets 
periodically fold and open as usual, excepting that the 
periods are somewhat lengthened ; on the other hand, 
when they are exposed to a continued light, these 
periods are shortened. When exposed to strong lamp- 
light by night, and excluded from ail light by day, 
* Descriptive and Physiological Botany. 
