14 TRANSACTIONS OF THE [OCT. 17, 



an insect. In the foregoing exj^eriments the slighter the irri- 

 tation the slighter appeared to be the chances of closing. 



The nature of the irritating object does not appear to effect 

 the rate of closing. 



3. Twenty-five examples similarly irritated but with muscle 

 of insect gave results similar to the foregoing ; the time of 

 closing varied between 1 and 20 seconds, two did not close, ten 

 interlocked. 



Continuous gentle pressure of filiaments by wisp appears to 

 close the trap gently and slowly, a provision perhaj^s of strategic 

 advantage in capturing prey. 



In these experiments was noted how variable appeared to be 

 the seat of sensitiveness. In some instances a single touch of 

 one of the filiaments would render closing instant ; in others all 

 filiaments might be touched without causing the traps to close, 

 or at the best would give rise to most tardy action. In one of 

 the latter cases an accidental touch at the anterior notch in the 

 line of the midrib caused rapid clo.sing. This suggested the 

 following experiments, which show that the point of closing is 

 not altogether localized in and at the base of the filiaments 

 (Cf. Ins. PI. 294). 



4. Ten examples were brushed by wisp along the margin 

 of the face of a lobe without approaching the filiaments. Eight 

 closed within 20 seconds — two of these as rapidly as if the 

 filiaments had been disti;rbed. 



5. Ten examples were irritated by binishing the wisp sharply 

 across the marginal spikes. None closed. 



6. Ten examples were stroked with wisp within the terminal 

 quarter inch of the hinge. All closed within 80 seconds — three 

 very rapidly. 



7. A similar experiment irritating the posterior half of the 

 hinge line gave practically the same results — two closing rapidly. 



In these instances, however, it appears as in the experiments 

 upon the tactile filiaments that especial interest is to be attached 

 to the present condition of each leaf. 



The foregoing experiments lead to the conclusion that the 

 majority of opened leaves would allow insects to pass over them 

 and would not entrap unless the visitor proved a lingering one. 

 It seems further evident that when a leaf has acquired or 

 regained its maximum degree of sensitiveness its instant closing 

 may result from irritation within the trap even when the 

 filiaments may not have been touched. The insect, however, 

 that passes over the trap has in general an exceedingly good 

 chance of escape, even granting that the trap commences to 

 close. Of a number of insects allowed to pass (slowly) ovrr the 



