PLANTS ON THE MOVE 191 



considerably lengthens its parabola. Some calyx 

 tubes, as in the allied genus Teucrium, are actually 

 rifled so as to give the shot a spin, on the principle 

 adopted not long since by the makers of our 

 rifles and ordnance. 



So much for the sling which, like the balloon, 

 is dependent on the wind for its functioning. 

 The artillery method practised by a great number 

 of plants attracts human admiration more quickly. 

 Every one knows the geraniums and the long 

 beaks they produce at seeding time, from which 

 they are known as cranesbills. These beaks are 

 purely shooting arrangements to be likened to the 

 barrels of cross-bows, from end to end of which 

 operate elastic springs to shoot the seeds. There 

 are five elastic straps attached at one end to the 

 tip of the beak, and at the other each to a fruit 

 at the bottom. The elastic strains and tightens 

 on the fruit, and at the right time the latter is 

 released, the strap curling sharply up in the 

 direction of the barrel. In late summer you find 

 every beak decorated with five curled straps and 

 apparently a fruit at each end. Long ago I 

 collected a handful of these ripe fruits and planted 

 them. Not one came up. I had collected merely 

 the empty catapults, for each carpel has a slit in 

 its envelope from which the seed is slung at the 

 instant when the elastic rolls up. The stork's bill 

 explodes in much the same way, but the elastic 

 remains on the seed in a twisted form that 

 enables it to hop along the ground and bury 



