Chap.XIIL MANNEK OF CAPTURING INSECTS. 



307 



instantly if their sensitive filaments are touched. 

 How many times a leaf is capable of shutting and 

 opening if no animal matter is left enclosed, I do 

 not know ; but one leaf was made to close four times, 

 reopening afterwards, within six days. On the last 

 occasion it caught a fly, and then remained closed for 

 many days. 



This power of reopening quickly after the filaments 

 have been accidentally touched by blades of grass, 

 or by objects blown on the leaf by the wind, as 

 occasionally happens in its native place,* must be of 

 some importance to the plant; for as long as a 

 leaf remains closed, it cannot of course capture an 

 insect. 



When the filaments are irritated and a leaf is made 

 to shut over an insect, a bit of meat, albumen, gela- 

 tine, casein, and, no doubt, any other substance con- 

 taining soluble nitrogenous matter, the lobes, instead 

 of remaining concave, thus including a concavity, 

 slowly press closely together throughout their whole 

 breadth. As this takes place, the margins gradually 

 become a little everted, so that the spikes, which at first 

 intercrossed, at last project in two parallel rows. The 

 lobes press against each other with such force that I 

 have seen a cube of albumen much flattened, with 

 distinct impressions of the little prominent glands; but 

 this latter circumstance may have been partly caused 

 by the corroding action of the secretion. So firmly do 

 they become pressed together that, if any large insect 

 or other object has been caught, a corresponding pro- 

 jection on the outside of the leaf is distinctly visible. 

 When the two lobes are thus completely shut, they 



* According to Dr. Cui-tis, in 'Boston Journal of Nat. Hist.' 

 vol. i. 1837, p.l23. 



