MARCH 



185 



The}' feed, likewise, upon the organic matter in the soil, 

 which they swallow in great quantities, and eject in the 

 form of the familiar " castings." • They are extraordi- 

 narily numerous in all humid regions, a fact that we 

 scarcely realize because they live in their burrows dur- 

 ing the day, emerging only at night for food and to work. 

 In cold or dry weather they are entirely quiescent. 



\F 



Egg Capsule 



Worm escaping 

 from Capsule 



It has been estimated that about ten tons of earth in 

 each acre of ground pass annually through their bodies 

 in places where they are numerous. By this means 

 fresh surfaces are kept continually exposed to the action 

 of carbon dioxide and the humus acids, and thus decom- 

 posed and disintegrated. 



Moreover, these '• castings " are distributed either by 



