Chap. XIII.] MANNER OP CAPTURING INSECTS. 24:9 



filaments having been touched, or if it includes an object not 

 yielding soluble nitrogenous matter, the two lobes retain 

 their inwardly concave form until they re-expand. The re- 

 expansion under these circumstances that is when no or- 

 ganic matter is enclosed was observed in ten cases. In all 

 of these, the leaves re-expanded to about two-thirds of the 

 full extent in 24 hrs. from the time of closure. Even the 

 leaf from which a portion of one lobe had been cut off opened 

 to a slight degree within this same time. In one case a leaf 

 re-expanded to about two-thirds of the full extent in 7 hrs., 

 and completely in 32 hrs.; but one of its filaments had been 

 touched merely with a hair just enough to cause the leaf 

 to close. Of these ten leaves only a few re-expanded com- 

 pletely in less than two days, and two or three required even 

 a little longer time. Before, however, they fully re-expand, 

 they are ready to close 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, gelatine, casein, 

 and, no doubt, any other substance containing soluble nitrog- 

 enous matter, the lobes, instead of remaining concave, thus 

 including a concavity, slowly press closely together through- 

 out 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 impres- 

 sions of the little prominent glands; but this latter circum- 

 stance may have been partly caused by the corroding action 



>* According to Dr. Curtis, in ' Boston Journal of Nat. Hist.' roi. 

 I. 1837, p. 123. 



