40 HARNESSING THE EARTHWORM 



of plants into their burrows, partly for the sake of plugging them 

 up and partly as food. 



The leaves which are dragged into the burrows as food, 

 after being torn into the finest shreds, partially digested, and satu- 

 rated with the intestinal and urinary secretions are commingled 

 with much' earth. This earth forms the dark-coloured, rich hu- 

 mus which almost everywhere covers the surface of the land with 

 a fairly well-defined layer or mantle . . . 



When we behold a wide, turf-covered expanse, we should 

 remember that its smoothness, on which so much of its beauty 

 depends, is mainly due to all the inequalities having been slowly 

 levelled by worms. It is a marvellous reflection that the whole 

 of the superficial mould over any such expanse has passed, and 

 will again pass, every few years through the bodies of worms. 

 The plough is one of the most ancient and most valuable of man's 

 inventions ; but long before he existed the land was in fact regu- 

 larly ploughed, and still continues to be ploughed, by earthworms. 

 It may be doubted whether there are many other animals which 

 have played so important a part in the history of the world, as 

 have these lowly organized creatures. 



In some of the soils of England, Darwin found earthworms 

 in concentrations of from 25.000 to 53,000 per acre, passing 

 through their bodies anoBnngmg" to the surface from ten to 

 eighteen tons of dry earth annually on each acre of land. Later 

 investigations carried out by the British Government in a more 

 favorable location than England, showed jm_ainniial_ volumejof^ 

 castings averaging more than 200 tons per acre. Notable in- 

 vestigators from the time of Darwin down to the immediate 

 present have corroborated his findings and have also shown that 

 Darwin was extremely conservative in his claims, both as to num- 

 bers of earthworms per acre as well as to the tonnage of castings 

 thrown up. 



Dr. Firman E. Bear, formerly professor of Soils, Ohio State 

 University, in his authoritative book on Theory and Practice in 

 the Use of Fertilizers, states : "In a study of earthworms in the 

 soil on the Ohio State University Farm, it was found that they 

 were present in plots of soil covered with bluegrass in numbers 

 averaging over one million per acre. These were concentrated, 



