292 THE KEASOJT WHY. 



1 He watereth the hills from his chambers ; the earth is satisfied with the 

 fruit of thy works." PSALM civ. 



something back ; but all kinds of plants do not absorb nor restore 

 the elements in the same proportions. Therefore a succession of 

 crops of one kind would soon impoverish the soil; but a succes- 

 sion of crops of different kinds will compensate the soil, in some 

 degree, for the nourishment withdrawn. 



1165. IV hy do farmers manure their lands ? 

 Because, as soils vary, and crops impoverish tke soils, the farmer 

 employs manure to restore fertility, and to adapt the soils to the 

 wants of tlie plants he desires to cultivate. 



It is remarkable that Nature herself points out to man the necessity for 

 changing the succession of vegetable growths. 



\Vhen plants have exhausted the soil upon which they grow, they will push 

 their roots far in search of sustenance, and in time migrate to a new soil, while 

 other plants will spring up and thrive upon the area vacated. When a forest in 

 North America is destroyed by fire, the trees that grow afterwards are unlike 

 those that the fire consumed, and evidently arise from seeds that have long lain 

 buried in the earth, waiting the time when the ascendancy of the reigning order 

 of plants should cease. 



1166. Why are grasses so widely diffused throughout nature? 

 Because they form the food of a very large portion of the animal 

 kingdom. They have therefore been abundantly provided. No 

 spot of earth is allowed to remain idle long. When the foot of man 

 ceases to tread down the path, grass immediately begins to appear ; 

 and by its universality and the hardihood of its nature, it clothes 

 the earth as with a carpet. 



Many grasses, whose leaves are so dry and withered that the plants appear 

 dead, revive and renew their existence in the spring by pushing forth new leaves 

 from the bosom of the former ones. Withering" s Botany, 



Grasses are Nature's care. With these she clothes the earth ; with these she 

 sustains its inhabitants. Cattle feed upon their leaves; birds upon their 

 smaller seeds ; men upon the larger ; for, few readers need be told that the 

 plants which produce our bread-corn, belong to this class. In those tribes 

 which are more generally considered as grasses, their extraordinary means and 

 powers of preservation and increase, their hardiness their almost unconquer- 

 able disposition to spread, their faculties of revivisccnce, coincide with the 

 intention of nature concerning them. They thrive under a treatment by which 

 other plants are destroyed. The more their leaves are consumed, the more 

 t heir roots increase. The more they are trampled upon, the thicker they grow. 

 Many of the seemingly dry and dead leaves of grasses revive, and renew their 

 verdure in the spring. In lofty mountains, where the summer heats are not 

 sufficient to ripen the seeds, grasses abound which are viviparous, and 

 consequently able to propagate themselves without seed. It is an observation, 

 likewise, which has often been made, that herbivorous animals attach 

 themselves to the leaves of grasses ; and, if at liberty in their pastures to rango 

 and choose, leave untouched the straws which support the flowers. Paley. 



