HYGROSCOPISM. 279 



the ground with the point. If allowed to fall among 

 low vegetation they become fixed in a more or less 

 oblique position, the seed resting on the ground. 

 The length of the feather renders entanglement easy^ 

 and, when a seed is once entangled, the hairs serve 

 to hold it fast and prevent the wind blowing it away. 

 The movement in the awn of Stipa spartea, an 

 allied species in the Red River colony, cause the 

 sharp, rigid points of the seed to enter and bury 

 themselves in the wool of the sheep with which the 

 grass comes into contact.^ Further than this, it is 

 affirmed that the seeds penetrate the skin by their 

 screw-like movement, and cause the death of the 

 animals. At the same time that hygroscopism 

 receives an illustration by these grasses, its utility is 

 demonstrated by the dissemination of the seeds, and 

 continuance of the species. In the Geranium family, 

 after the ovules are fertilised, the centre of the recep- 

 tacle continues to grow until it is prolonged into a 

 long beak, with the seeds arranged around the base, 

 and the elongated styles applied to the sides of the 

 beak. The peculiar beak-like form which the fruit 

 thus assumes has acquired for the plants the popular 

 names of Crane's-bill, Stork's-bill, &c. The mode in 

 which the carpels are loosened at the base, and curl 

 upwards like a watch-spring to the top of the beak, is 



^ See Museum No. 2, Royal Gardens, Kew. 



