87 



between, till one by one the seeds spring out with considerable 

 force. 



Some of tbe Crane's-bills lling" their seeds to a considerable 

 distance by means of a more complicated apparatus. The fruit 

 consists of five separate carpels attached by their apices to a 

 spindle. Each carpel consists of an egg-shaped pouch containing 

 one seed, prolonged into a slender rod, the whole adpressed to the 

 spindle, so that the five pouches lie in a ring round its base. Each 

 pouch is open on the side which is pressed against the spindle. 

 As the fruit ripens, the more rapid shrinking of the outer layers 

 of the rod of the carpel causes it to rupture the tissue winch at- 

 taches it by its whole length to the spindle, and it curls with a 

 jerk, carrying up the pouch, and causing the seed to fly out of the 

 opening on its inner side already referred to. Lord Avebury 

 placed fruits of the Herb Robert on his billiard table, and found 

 that the seeds were in this manner projected to a distance of over 

 twenty feet. Fruits of this kind have been aptly named sling- 

 fruits. Nor is it beyond the powers of certain species to under- 

 take even the planting of their seeds. 



The Stork's-bills (Erodium), which are closely allied to the 

 Crane's-bills or Geraniums, have curious fruits, each consisting of 

 a torpedo -shaped seed prolonged into a slender twisted rod, which 

 terminates in a long appendage set at right angles to the axis of 

 the remainder of the fruit. The seed is furnished with bristles 

 pointing away from the unattached end; and the twisted tail is 

 hygroscopic — very sensitive to moisture. Now, if the seed be 

 held fast, and the whole moistened, t lie rod will untwist, and, as a 

 result, the free end will revolve like the hand of a clock. But if, 

 as will more likely happen in Nature, this revolution causes the 

 long appendage to come in contact with some obstacle — a blade 

 of grass, for instance — then the motion will be transferred to the 

 seed-bearing end, which will revolve like an auger, and, as a 

 result of the lengthening caused by the untwisting of the rod, the 

 seed will be forced into the ground. The upward-pointing bristles 



