CHAP. I. ACTION OF THE 1 ARTS. 9 



Preliminary Sketch of the Action of the several Parts, and 

 of the Manner in ivhich 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 

 more 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 

 bmshed, 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 

 ander half an hour. 



* 'Bnt. Zeitung,' 1860, p. 246. 



