96 MANUAt OP NATURS STUDY. 



1. Where ground is tilled, these earth-worms 

 help to carry water from the surface to the tile ditch, 

 and thus help in the drainage. 



2. In time of rain after a long dry spell, they 

 help the water to soak into the ground rather than 

 have it run off into ditches, and thereby become 

 wasted so far as the plants are concerned. ' 



3. They reclaim waste land by bringing dirt to 

 the surface and covering up stony places, etc. 

 Henson estimated the amount of dirt brought to 

 the surface to be about 36 tons to the acre per year. 

 Darwin's estimate was about half that amount. On 

 an average, according to Henson, there are 53767 

 worms to the acre, or 36.5 tons. 



The ants, also, do an immense amount of exca- 

 vating and opening up the soil so as to make it 

 more conducive to the health of the plant. Bees 

 help in the fertilization of flowers and thus pay 

 for all the honey obtained. The same may be said 

 of the hornets, yellowjackets, bumble bees, etc. 

 The butterfly and moth also aid in this, but their 

 larvae are destructive to the life of the plant. But 

 then, again, insect-eating birds destroy the larvae 

 and thereby repay by way of defence to the plant. 

 Birds help in the distribution of plant seed. Ani- 

 mals of various kinds help in the dissemination of 

 seed. How? The excrement of animals and birds 



