THE SEED. 47 



4th. Exclusion of Light. The manner in which self- 

 <5own seeds in the forest are covered with fallen and 

 decaying foliage, plainly indicates that nature never 

 intended the light to strike germinating seeds. A seed 

 entirely exposed would be at one time saturated with 

 moisture, and at another parched with drought ; chemical 

 changes would be alternately promoted and checked, 

 until the vital principle would be destroyed, or so weaken- 

 ed as to produce a feeble and worthless plant. The depth 

 of the covering should always be regulated by the size of 

 the seeds. Small and delicate seeds may be sown almost 

 on the surface, whilst large ones may be imbedded to the 

 depth of four or five inches. The small seed requires 

 little moisture, and has but a feeble force to penetrate an 

 earthy covering ; but the large requires much moisture, 

 and has force enough to push its way up. 



