THE EARTHWORM IN SCIENTIFIC LITERATURE 47 



The well-known fertility of the Nile Valley is an example 

 a two thousand-mile stretch of land which is literally one vast bed 

 of earthworm soil, ideally qomposted and laid down, layer by 

 layer, and subjected to the digestion of earthworms in a favor- 

 able environment. While we have given the Valley of the Nile 

 as an example, all the fertile river valleys and bottom lands of 

 the earth could be cited with equal truth as illustrations of the 

 important work of earthworms in the building of topsoil. Many 

 plant growth experiments have been carried out in verification of 

 the claims made for earthworm castings and soil that has been 

 worked over by earthworms. Further on in this book we shall 

 give other reports, but it is appropriate at this point in the dis- 

 cussion to cite a few. 



In the book Soils: Their Formation, Properties, Composition 

 and Relations to Climate and Plant Growth, by E. W. Hilgard 

 (Ph.D., L.L.D., one time Professor of Agriculture in the Univer- 

 sity of California and formerly Director of the California Ex- 

 periment Station) we find in part*: 



Wolney has shown by direct experimental cultures in boxes,, 

 with and without earthworms, surprising differences between the 

 cultural results obtained, and this has been fully confirmed by 

 the subsequent researches of Djemil. In Wolney 's experiments, 

 the ratio of higher production in the presence of worms varied 

 all the way from 2. 6 percent in the case of oats, 63.9 percent in 

 that of rye, 135.9 percent in that of potatoes, 140 percent in 

 vetch, and 300 percent in that of the field pea, to 733 percent in 

 the case of rape. 



From among many reports received from practical earth- 

 worm culturists, we will give part of a letter from a Georgia 

 farmer, Mr. R. A. Caldwell ; we quote : 



I have planted Moss Rose in experimental pots, same age and 

 condition, one pot with worms, one without: invariably, the one 

 with the worms will take on new zest and life, and I have hacl 



*Pages 158-159 



