132 LIFE OF A TREE. 
flowers, some of which lie asleep when all the 
rest of the sun-lit world 1s awake and astir, and 
only put forth their beauties to the air of night. 
Dr. Lindley tells us that the wnotheras unfold 
their blossoms to the dews of evening, but 
wither away at the approach of day. And the 
splendid cereus, from which we lately parted, 
also only displays its glowing colours and exqui- 
site form in the darkness of the conservatory. 
That however, in the generality, the sleep of 
plants is due to the withdrawal of the sun’s rays, 
is sufficiently evident from some curious ex- 
periments performed by the French botanist De 
Candolle. He found that he could reverse the 
order of opening in flowers, by means of artificial 
light, and caused those which he experimented on 
to close during the day by keeping them in the 
dark, and to open at night by exposing them 
to the blaze of lamps and candles. We are 
unable to explain how light acts in this remark- 
able way; and from the exceptions just mentioned 
to the general rule, we can only conjecture that 
it cannot be altogether due to the influence of 
light, but that some other cause must exist, which 
has something to do in the production of the 
