PROPAGATION OF THE SPECIES. CHAP. IX. 



some species in particular, as has been already 

 stated ;* or the care with which nature has provided 

 for the dispersion of the ripened seed. 



And dis- If seeds were to fall into the soil merely by dropping 

 down from the plant, then the great mass of them 

 instead of germinating and springing up into distinct 

 plants, would tend only to putrefaction and decay ; 

 to prevent which consequence nature has adopted a 

 variety of the most efficacious contrivances, all tend- 

 ing to the dispersion of the seed. 



By the The first means I shall mention is that of the 

 of the peri- elasticity of the pericarp of many fruits, by which it 

 opens when ripe with a sort of sudden spring, eject- 

 ing the seed with violence, and throwing it to some 

 considerable distance from the plant. This may be 

 exemplified in a variety of cases ; the seeds of oats 

 when ripe are projected from the calyx with such 

 violence, that in a fine and dry day you may even 

 hear them thrown out with a slight and sudden snap 

 in passing through a field that is ripe. The pericarp 

 of the Dorsiferous Ferus is furnished with a sort of 

 peculiar elastic ring, intended as it would appear 

 for the very purpose of projecting the seeds. The 

 capsules of the Cucumber, Geranium, Geum, and 

 Fraxinelta, discharge their seeds also when ripe 

 with an elastic jerk. But the pericarp of Impatiens, 

 which consists of one cell with five valves, exhibits 

 perhaps one of the best examples of this mode of 

 dispersion. If it is accidentally touched when ripe 

 * Book i. chap iii. 



