202 OF PLANTS. 



security would interfere with other uses. Many species 

 of animals would suffer, and many perish, if they could 

 not obtain access to them. The plant would overrun the 

 soil ; or the seed be wasted for the want of room to sow it- 

 self. It is, sometimes, as necessary to destroy particular 

 species of plants, as it is, at other times, to encourage their 

 growth. Here, as in many cases, a balance is to be main- 

 tained between opposite uses. The provisions for the pre- 

 servation of seeds appear to be directed, chiefly against the 

 inconstancy of the elements, or the sweeping destruction 

 of inclement seasons. The depredations of animals, and 

 the injuries of accidental violence, are allowed for in the 

 abundance of the increase. The result is, that, out of 

 the many thousand different plants which cover the earth, 

 not a single species, perhaps, has been lost since the crea- 

 tion. 



When nature has perfected her seeds, her next care is 

 to disperse them. The seed cannot answer its purpose, 

 while it remains confined in the capsule. After the seeds 

 therefore are ripened, the pericarpium opens to let them 

 out ; and the opening is not like an accidental bursting, 

 but, for the most part, is according to a certain rule in 

 each plant. What I have always thought very extraordina- 

 ry, nuts and shells, which we can hardly crack with our 

 teeth, divide and make way for the little tender sprout 

 which proceeds from the kernel. Handling the nut, I 

 could hardly conceive how the plantule was ever to get 

 out of it. There are cases, it is said, in which the seed- 

 vessel by an elastic jerk, at the moment of its explosion, 

 casts the seed to a distance. We all however know, that 

 many seeds (those of the most composite flowers, as of the 

 thistle, dandelion, &c.) are endowed with what are not 

 improperly called wings ; that is, downy appendages, by 

 which they are enabled to float in the air, and are carried of- 

 tentimes by the wind to great distances from the plant 

 which produces them. It is the swelling also of this downy 

 tuft within the seed-vessel, that seems to overcome the re- 

 sistance of its coats, and to open a passage for the seed to 

 escape. 



But the constitution of seeds is still more admirable than 

 cither their preservation or their dispersion. In the body 

 of the seed of every species of plant, or nearly of every one, 

 provision is made for two grand purposes ; first, for the 

 safety of the germ ; secondly, for the temporary support of 

 the future plant. The sprout, as folded up in the seed, is 



