24 HANDY-BOOK OP HUSBANDRY. 



room, it wilts and shrivels up, losing much of its weight. This 

 results from the drying out of the water with which its pores are 

 filled. If it is allowed to become rotten, it loses much more 

 of its bulk, its texture is broken up, and it gives off foul odors. In 

 this case it loses a part of its own substance, (not only the 

 water which filled its pores and gave it its natural form, but 

 a part of the very material by which its pores are surrounded,) 

 and, if kept under circumstances favorable to decomposition, it 

 will finally be reduced to a blackened mass, almost a mould, 

 with no indication of its original form, and with not a twen- 

 tieth part of its original weight. If this small residue is burned, 

 only a handful of ashes will remain of the once luxuriant grass. 

 The same result would come of a like treatment of every plant 

 that grows. Some would be more and some less rapidly reduced 

 by the original decay, while fire, which is only a more active decay, 

 would drive away water, fiber, bark, leaves, and roots, and leave 

 only the ashes behind. 



Our grass is destroyed, — where has it gone ? The water has 

 " dried up," become vapor, and gone to help make the rains and 

 the dew. The gum and stafcti, and flesh-forming parts have 

 rotted away, and have floatecj off as gases into the air whence 

 they originally came, and where they are again on duty, ready to 

 enter the leaves of plants, or, being dissolved by the moisture of 

 the soil, to travel up their roots and again take on a useful form. 

 The woody matters that have burned away have followed the 

 same law, and will follow it again and again as long as growth 

 and decay last. All that remains to us is our poor handful of 

 gray ashes, — this is the only part of our grass that can be sup- 

 plied by the soil alone, and to the soil we must give it again. 



Let us now examine the different sources of plant-food : — 



A fertile soil contains various proportions of clay and sand, 

 and mixed earthy substances and decayed vegetable matter ; these, 

 together, forming nearly its whole bulk, and acting in a mechanical 

 rather than in a chemical manner upon the growth of plants. 



