Cuar. XIII. MANNER OF CAPTURING INSECTS. 305 
to reopen after 20 hrs. Lastly another leaf was exposed for 4 m. 
to only four drops of the ether; it was rendered insensible, and 
did not close when its filaments were repeatedly touched, but 
closed when the end of the open leaf was cut off. This shows 
either that the internal parts had not been rendered insensible, 
or that an incision is a more powerfu! stimulus than repeated 
touches on the filaments. Whether the larger doses of chloro- 
form and ether, which caused the leaves to close slowly, 
acted on the sensitive filaments or on the leaf itself, I do not 
know. 
Cyanide of potassium, when left in a bottle, generates prussic 
or hydrocyanic acid. A leaf was exposed for 1 hr. 85 m. to the 
vapour thus formed; and the glands became within this time 
so colourless and shrunken as to be scarcely visible, and I at 
first thought that they had all dropped off. The leaf was not 
rendered insensible; for as soon as one of the filaments was 
touched it closed. It had, however, suffered, for it did not 
reopen until nearly two days had passed, and was not even 
then in the least sensitive. After an additional day it recovered 
its powers, and closed on being touched and subsequently re- 
opened. Another leaf behaved in nearly the same manner after 
a shorter exposure to this vapour. 
On the Manner in which Insects are caught.—We will 
now consider the action of the leaves when insects 
happen to touch one of the sensitive filaments. This 
often occurred in my greenhouse, but I do not know 
whether insects are attracted in any special way by 
the leaves. They are caught in large numbers by the 
plant in its native country. As soon as a filament is 
touched, both lobes close with astonishing quickness ; 
and as they stand at less than a right angle to each 
other, they have a good chance of catching any in- 
truder. The angle between the blade and footstalk 
does not change when the lobes close. The chief seat 
of movement is near the midrib, but is not confined 
to this part; for, as the lobes come together, each 
curves inwards across its whole breadth; the marginal 
spikes however, not becoming curved~ This move 
