Cuar. L ACTION OF THE PARTS. 9 
Preliminary Sketch of the Action of the several Parts, and 
of the Manner in which Insects are Captured. 
If a small organic or inorganic object be placed on 
the glands in the centre of a leaf, these transmit a 
motor impulse to the marginal tentacles. The nearer 
ones are first affected and slowly bend towards the 
centre, and then those farther off, until at last all 
become closely inflected over the object. This takes 
place in from one hour to four or five or more hours. 
The difference in the time required depends on many 
circumstances; namely on the size of the object and 
on its nature, that is, whether it contains soluble 
matter of the proper kind; on the vigour and age of 
the leaf; whether it has lately been in action; and, 
according to Nitschke,* on the temperature of the 
day, as likewise seemed to me to be the case. A living 
insect is a more efficient object than a dead one, as 
in struggling it presses against the glands of many 
tentacles. An insect, such as a fly, with thin integu- 
ments, through which animal matter in solution can 
readily pass into the surrounding dense secretion, is 
mote efficient in causing prolonged inflection than an 
insect with a thick coat, such as a beetle. The inflec- 
tion of the tentacles takes place indifferently in the 
light and darkness; and the plant is not subject to 
any nocturnal movement of so-called sleep. 
If the glands on the disc are repeatedly touched or 
brushed, although no object is left on them, the 
marginal tentacles curve inwards. So again, if drops 
of various fluids, for instance of saliva or of a solu- 
tion of any salt of ammonia, are placed on the central 
glands, the same result quickly follows, sometimes in 
under half an hour. 
* ‘Bot. Zeitung, 1860, p. 246. 
