2'76 PRINCIPLES OF BOTANY, ETC. 
and fall down; if single leaves or the main 
footstalk be touched, they remain contracted for 
some minutes. Almost all triangular leaves, and 
leaves which are composed of several small ones, 
contract at night time, like the above plants, 
in such a manner that one leaf covers the other, 
and the whole becomes, as it were, compressed. 
Whoever will take the trouble to examine the 
plants of a garden at night-time with a lantern in 
his hand, will find several of them in this state, 
which has been compared to sleep, (§ 7). ‘There 
are plants which, at a certain hour in the day, open 
and close their leaves. Du Hamel made experi- 
ments with the Mimosa sesitiva, which at a certain 
hour in the evening shuts its leaves, and again at a 
certain time opens them in the morning. He put 
this plant in a leathern trunk, covered with woollen 
blankets, and found that its leaves opened at a certain 
hour in the morning, and again were shut up in the 
evening. It has been alleged, that this phenomenon 
varies in its period, when going on in vacuo. 
A plant which grows in the marshes of South 
Carolina, known under the name of Dionoea Mus. 
cipula has a singularly constructed leaf. At the apex 
of a lanceolate leaf an elongation is seen armed with 
short prickles, which as soon as an insect or other 
sinall body is put upon it, shuts itself, and does not 
open, till the body caught by it becomes quiet. 
The species of Drosera rotundifolia and longifolia, 
the leaves of which are provided on their margins 
and 
