36 SOWING SEEDS. [CHAP. HI. 



pot; and there can be no doubt that, this is 

 done in order that the seeds may be firmly 

 embedded in the soil. When lawns are sown 

 with grass seeds also, the seeds are frequently 

 rolled in, evidently for the same purpose. The 

 only question, therefore, is, why is this neces- 

 sary ? and the answer appears to be, that a 

 degree of permanence and stability is essential 

 to enable nature to accommodate the plant to 

 the situation in which it is placed. When there 

 is this degree of permanence and stability, it is 

 astonishing to observe the efforts that plants 

 will make to provide for their wants; but, with- 

 out it, seeds will not even vegetate. Thus we 

 often see large trees springing from crevices in 

 apparently bare rocks, or from the walls of 

 neglected buildings ; while not even a blade of 

 grass will grow among the moving sands of a 

 desert. 



The reasons for the second and third points, 

 of covering the seeds and yet not covering them 

 too deeply, appear more obvious ; and yet they 

 also require a little explanation. The seeds are 

 covered to keep them in darkness, and to retain 

 round them a proper quantity of moisture ; not 

 only to make them swell and begin to vegetate, 

 but to enable the roots to perform their proper 

 functions; since, if too much exposed to the 

 air, they would become dry and withered, and 

 lose the power of contracting and dilating, 

 which is essential to enable them to imbibe and 

 digest their food. Burying the seeds too deeply 

 is obviously injurious in impeding the progress 

 of the young shoot to the light, and in placing 

 it in an unnatural position. When a seed 



