62 The dwellers in the soil 



you to be an inch long, and if you looked down into 

 the soil, it would seem to you to be an extraordinarily 

 wonderful place. The little grains of soil would look 

 like great rocks and on them you would see creatures 

 of all shapes and sizes moving about, and feeding 

 on whatever was suitable to them, some being de- 

 stroyed by others very much larger than themselves, 

 some apparently dead or asleep, yet waking up when- 

 ever it becomes warmer or there was a little more 

 moisture. You would see them changing useless dead 

 roots and leaves into very valuable plant food ; indeed 

 it is they that bring about the changes observed in the 

 experiments of Chap. vi. Occasionally you would see 

 a very strange sight indeed — a great snake-like creature, 

 over three miles long and nearly half a mile round, 

 would rush along devouring everything before it and 

 leave behind it a great tunnel down which a mighty river 

 would suddenly pour, and what do you think it would 

 be ? What you now call an earthworm and think is 

 four inches long, going through the soil leaving its 

 burrow along which a drop of water trickles I That 

 shows you how tiny these little soil creatures are. 



These busy little creatures are called micro- 

 organisms because of their small size. But they are 

 not all useful. Some can turn milk bad as we have 

 already seen, and therefore all jugs and dishes must be 

 kept clean lest any of them should be present. Others 

 can cause disease. It has happened that a child who 

 has cut its finger and has got some soil into the cut, 

 and not washed it out at once, has been made very 

 ill. You may sometimes notice sheep limping about in 

 the fields, especially in damp fields ; an organism gets 

 into the foot and causes trouble. 



