PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 129 



ground, and many wingless insects are thus induced to climb up the alluring path 

 and to enter the cavity of the pitcher. Darlingtonia, on the other hand, is 

 destitute of honey on its decurrent ridge, and only provides the sweet meal at the 

 top in the vicinity of the orifice, where it is available for flying insects, which, as a 

 rule, only visit nectar-secreting flowers. The purplish-red scale, shaped like a fish's 

 tail, and hung out like the sign-board of an inn in front of the entrance to the 

 pitcher, constitutes an instrument for the attraction, from afar, of these winged 

 creatures, which are endowed with a vivid sense of colour; and, as experience 

 shows, it does not fail in its object. 



What significance is to be attributed to the spiral torsion of Darlingtonia 

 leaves (see fig. 21 2 ) it is difficult to say. Perhaps the escape of animals once 

 imprisoned in the depths of a pitfall is hereby rendered more remote. It would at 

 all events be much more difficult for an insect trying to escape by the use of its 

 wings to ascend a canal which, in addition to being lined with decurved points, 

 was spirally wound, than a similar canal, straight and widened towards the top. 

 We must not omit to mention that a few flies and a small moth have selected as 

 their ordinary habitat the pitchers of both the plants just described, in spite of their 

 being so fatal to most insects. The grubs of a blow-fly (Sarcoj>haga Sarraceniai), 

 in particular, live in large numbers amidst the heaps of decaying insect bodies at 

 the bottom of the pitchers, and are there nourished just as are the grubs of allied 

 species in the rotten flesh of birds and mammals. When mature, the grubs quit 

 the environment of dead remains, passing through holes which they bore in the 

 side wall of the pitcher, and turn into chrysalises in the earth. But the fly itself 

 can without danger pass in and out of the pitfalls, which are so perilous in the case 

 of other insects, and it is enabled to do this by means of the special structure of its 

 feet. On the last joint of each foot it has a long claw and sole-like attachment-lobe, 

 and it is able to push these appendages between the sharp, slippery, decurved hairs 

 lining the inner surface of the pitcher, and so to hook itself to the deeper strata of 

 the wall. This apparatus may be likened to the grapple-like climbing irons of 

 Tyrolese mountaineers, and, thus armed, the fly is in a position to ascend the inner 

 wall of a pitcher unscaleable by other insects. The case of the small moth 

 Xanthoptera semicrocea is similar. The tibiae of this insect are armed with long, 

 sharp spurs, one pair on each of the two middle legs, and two pairs on each of 

 the two hindermost legs; and, by the help of these spurs it likewise is able to 

 tread uninjured over the dangerous surface of the wall. Its caterpillars, too, cover 

 the sharp slippery hairs with a web, and so render them harmless. 



The presence of these animals in the death-traps of Sarracenias is of special 

 interest, inasmuch as it shows that the animals which perish at the bottom of the 

 pitchers are not exactly digested. If maggoty flesh enters the stomach of a 

 carnivorous animal, not only the flesh itself but the maggots as well (which, indeed, 

 immediately die on reaching the stomach) are speedily dissolved by the action of 

 the gastric juice. Such is also the case with several animal-capturing plants to be 

 described in the next pages. But the fluid secreted in the pitchers of Darlingtonia 



Vol, I. 9 



