312 DIONHA WUSCIPUL«. Cuap. XIIL 
creasing darkness; and one of my sons actually saw a 
small insect thus escaping. A moderately large in- 
sect, 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, how- 
ever, would be able to free itself, and Mrs. Treat saw 
this effected by a rose-chafer (Macrodactylus subspi- 
nosus) 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 afterwards re- 
covering its sensibility ; inasmuch as a minute insect 
would afford but little nutriment. It would be 
far better 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 naturally 
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 scolo- 
pendra. Out of these ten insects, no less than eight 
