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lustrate their analogous condition. Bees, wasps, 
house flies, butterflies, are well known as diurnal, 
most beetles and moths as nocturnal animals. Many 
plants, it is well known, are nocturnal, as the night- 
flowering stock and cereus. Several expand their 
blossoms with the dawn of day, and close them at 
noon, as anagallis. Tulips and anemones close their 
petals at eve, when cenothere open them. Ferraria 
tigridia expands about three hours before noon, and 
droops in as many after it. But nightly sleep, or a 
condition strikingly analogous to it, may in a cer- 
tain sense be predicated of all plants. I shall ex- 
hibit this proposition in the clear words of Mrs. Mar- 
cet, Conversation VII. on the action of Light and 
Heat on Plants. 
“B. The first rays of the rising sun seem to awaken 
the vegetable creation from a state of repose. 
* C. You do not mean to infer that plants sleep 
during the night ? 
« B. I doubt whether the term sleep be literally 
appropriate to that state of relaxation and inaction 
which appears to afford them repose during that 
season. The leaves and flowers usually change their 
position as soon as it grows dark; in many plants 
the leaves drop; in others they close, as well as the 
petals of the flowers, and are opened by the first 
rays of the morning sun. The leaves then recom- 
mence their chemical operations; the spongioles 
(porous roots) draw up a provision for their labours ; 
every function, which had ceased or diminished dur- 
ing the night, is again renewed, and the whole plant 
