SOME PLANTS WHICH EXT UAL' INSECTS. 419 



death is followed by decomposition, and in the absorption of the prod- 

 ucts of this the plant accomplishes the end for which it possesses the 

 traps — it gets its needed nitrogen. 



In the pitcher-plants the urns of water are set and all else is left 

 to the curiosity of the insects, the inner structure of the leaf being 

 such — as we shall soon see — that a secure trap-door is not needed. 

 The half dozen species of pitcher-plant (Sarracenia) exhibit consid- 

 erable variety in the form of their leaves. In the purple species, the 

 only one growing north of Virginia, 

 the leaves form a rosette-like cluster 

 procumbent on the mud or moss and 

 bent upward so as to give the mouth a 

 horizontal position. The stalk is ex- 

 ceedingly short and the leaves, heavy 

 with water, never rise above the sur- 

 face of the swamps and bogs which are 

 the only home of the plant. At bloom- 

 ing time a stalk is sent upward for 

 a foot or more, bearing the curious 

 leathery flowers which nod to one side Fig , A LoNGITUDINAL Section of a 

 in a manner which has led some one bladderwort trap greatly enlarged, 



j, . . -, ,■ m xl • SHOWING THE HAIKS, THE MOUTHANDTHE 



01 vivid imagination to call this TRAP . D00K 

 the ' side-saddle plant.' The water 



which fills all but the youngest of the leaves is simply rain-water 

 which has fallen in, and has nothing to do with the water supply of 

 the plant in the ordinary sense. In the water are pretty sure to be 

 some struggling insects trying to float or to crawl up the sides of the 

 pitcher, some others whose struggles are over, and the remaining legs 

 and wings of still earlier victims. All sorts of flying and creeping 

 things seem to have a natural curiosity to examine hollow caverns such 

 as the pitchered leaves appear to them. Perhaps, too, they are drawn 

 to the plant by its rich red coloration or the striking veins which mark 

 the mouth of the pitcher; indeed, one botanist has found drops of 

 honey arranged in a row up the side of the pitcher, a lure to guide the 

 steps of the insect directly to the interior. The wing which runs up 

 one side has been thought, too, to serve a use in preventing insects 

 from crawling round and round the pitcher, and to direct their steps 

 upward to the slippery edge of the mouth. Once falling from the 

 edge into the water, slim indeed, is the chance that any but the most 

 active of insects will get out. The sides of the interior are not only 

 steep, but are exceedingly smooth and offer no foothold by which to 

 regain the top. And even if the bedraggled creature should succeed in 

 crawling up beyond the slippery zone it would encounter an array of 

 long stout hairs crowded close together and pointing downward. Over 

 this ambush none but the most long-legged of insects can crawl, and 



