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POPULAR SCIENCE MOXTHLY. 



one has become entangled all the hairs will take part in the movement, 

 and even the blade of the leaf may be bent together in such a way as 

 to aid in the aggregation of the tips. The globules of jelly fuse into 

 a mass about the insect and there is poured out from the glands a 

 digestive juice such as that in the East Indian pitcher-plant and the 

 butterwort. All the soft parts of the insect are digested and the 

 nutritive juices, rich in nitrogen, are absorbed by the very same glands 

 which secreted the digestive juice. 



It is obvious that the aggregation of the hairs causes a more com- 

 plete surrounding of the insect with jelly, increases the amount of 

 digestive juice brought to act upon it, and also the number of channels 

 for conducting the juices back into the leaf. The movements here in- 

 volved are comparatively rapid 

 — the hairs nearest the one 

 which has made a capture begin 

 to move in five seconds; if the 

 capture is a big one all the hairs 

 will be aggregated about it in 

 half an hour. The time re- 

 quired for the digestion of prey 

 depends entirely upon its size 

 and nature; when completed the 

 jelly dries off from the glands, 

 the hard indigestible parts of 

 the insect blow away, and the 

 hairs resume their usual posi- 

 tions. The globules of jelly 

 are then renewed and the leaf 

 is ready for another capture. 

 A single leaf may partake of 

 above one hundred such meals, 

 but more commonly its life is 

 shorter, its place being rapidly 

 taken by a younger leaf. 

 These are highly complex structures with which we meet in the 

 sun-dew, and the united action of the hairs in aggregating themselves 

 towards the spot where an insect has alighted is an example of co- 

 ordinated activity such as is rarely met with in the plant world. There 

 are, however, no unusual structures here, there is nothing in any way 

 resembling a nervous system and nothing suggesting any similarity 

 to the coordinated movements of animals which they so closely resemble. 

 The most highly developed and remarkable of the insectivorous 

 plants is the Venus' fly-trap (Dioncea), which will never cease to be 

 the cardinal attraction with all florists so fortunate as to be able to 



■f /# 



1 



Fig. 9. The Cup of Another Species of 

 East Indian Pitcher-plant. Note the two 

 directive wings on the outside and the ridge 

 just inside the mouth. 



