INSECTIVOROUS PLANTS. 301 



when a small fly aliglits upon a leaf a little below its 

 slender apex, or when a bit of crushed fly is there 

 affixed, within a few hours the tip of the leaf bends 

 at the point of contact, and curls over or around the 

 body in question; and Mrs. Treat even found that 

 when living flies were pinned at half an inch in dis- 

 tance from the leaves, these in forty minutes had bent 

 their tips perceptibly toward the flies, and in less than 

 two hours reached them ! If this be confirmed — and 

 such a statement needs ample confirmation — then it 

 may be suspected that these slender leaves not only in- 

 curve after prolonged contact, just as do the leaf -stalks 

 of many climbers, but also make free and independent 

 circular sweeps, in the manner of twining stems and 

 of many tendrils. 



Correlated movements like these indicate pui'pose. 

 When performed by climbing plants, the object and 

 the advantage are obvious. That the apparatus and 

 the actions of Dionsea and Drosera are purposeless and 

 without advantage to the plants themselves, may have 

 been believed in former days, when it was likewise 

 conceived that abortive and f unctionless organs were 

 specially created " for the sake of symmetry " and to 

 display a plan ; but this is not according to the genius 

 of modern science. 



In the cases of insecticide next to be considered, 

 such evidence of intent is wanting, but other and cir- 

 cumstantial evidence may be had, sufficient to warrant 

 conviction. Sarracenias have hollow leaves in the 

 form of pitchers or trumpet-shaped tubes, containing 

 water, in which flies and other insects are habitually 

 drowned. They are all natives of the eastern side of 



