Chap. XIII.] MANNER OP CAPTURING INSECTS. 253 



from the iV to the iV of an inch (1.693 to 2.540 mm.) in 

 breadth, according to the size of the leaf, are left open. 

 Thus an insect, if its body is not thicker than these measure- 

 ments, can easily escape between the crossed spikes, when 

 disturbed by the closing lobes and increasing darkness; and 

 one of my sons actually saw a small insect thus escaping. 

 A moderately large insect, on the other hand, if it tries to 

 escape between the bars will surely be pushed back again 

 into its horrid prison with closing walls, for the spikes con- 

 tinue to cross more and more until the edges of the lobes- 

 come into contact. A very strong insect, however, would be 

 able to free itself, and Mrs. Treat saw this effected by a 

 rose-chafer (Macrodactylus subspinosus) in the United 

 States. Now it would manifestly be a great disadvantage to 

 the plant to waste many days in remaining clasped over a 

 minute insect, and several additional days or weeks in after- 

 wards recovering its sensibility; inasmuch as a minute in- 

 sect would afford but little nutriment. It would be far bet- 

 ter for the plant to wait for a time until a moderately 

 large insect was captured, and to allow all the little ones 

 to escape; and this advantage is secured by the slowly 

 intercrossing marginal spikes, which act like the large 

 meshes of a fishing-net, allowing the small and useless fry 

 to escape. 



As I was anxious to know whether this view was correct 

 and as it seems a good illustration of how cautious we 

 ought to be in assuming, as I had done with respect "to the 

 marginal spikes, that any fully developed structure is useless 

 I applied to Dr. Canby. He visited the native site of the 

 plant, early in the season, before the leaves had grown to 

 their full size, and sent me fourteen leaves, containing natu- 

 rally captured insects. Four of these had caught rather 

 small insects, viz. three of them ants, and the fourth a rather 

 small fly, but the other ten had all caught large insects, 

 namely, five elaters, two chrysomelas, a curculio, a thick and 

 broad spider, and a scolopendra. Out of these ten insects, 

 no less than eight were beetles," and out of the whole four- 



" Dr. Canby remarks (' (Jar- after a short time are rejected." 



dener'8 Monthly,' Aug. 1808). I am surprised at this statement. 



" as a general thing beetles and at least with respect to such 



insects .o/ that kind, though ai- beetles as elaters, for the Ave 



ways killed, seemed to be too which I examined were in an 



hard-shelled to serve as food, and extremely fragile and empty con- 



