64 THE GARDEN OF EARTH 



soon lend help. Their roots creep down quietly into 

 the cracks and force the sides more widely apart, and 

 as they die and decay they become part of the soil, 

 fitting it for use. 



Then as the soil goes on improving, and plants of a 

 higher make can thrive there, these also shed their 

 leaves and the leaves decay, and by and by the plants 

 die also. All this enriches the earth more and more. 



Soil that is formed only or chiefly of broken and 

 crumbled rock may be spoken of simply as " earth " or 

 " earth- mould," but when a large amount of leaves 

 and dead plants have been added it becomes " vegetable- 

 mould." It is then of far greater value. 



Many different kinds of food required by plants — 

 such as potash, soda, magnesia, lime — are found in soils ; 

 and each particular kind of plant must have its own 

 especial kinds of food, to keep it in good health. What 

 suits the constitution of one will often not do at all for 

 another. 



II — The Work of Worms 



A curious fact comes in here about the manner in 

 which earth is changed into good mould. Some way 

 back it was remarked that worms have a certain work 

 of their own to carry out, and very important work too. 



Many of us have perhaps looked upon worms as ugly 

 slimy, useless creatures, unpleasant to handle. Well, 

 they may be ugly, and they certainly are slimy. But 

 useless they are not. 



It is believed that they have no power of sight, 

 though light does faintly affect part of their bodies; 

 so far as is known, they have no means of hearing; 



