THE EARTHWORM IN SCIENTIFIC LITERATURE 43 



an unfailing supply of earthworm food in excessive abundance, 

 properly composted with all the chemical elements and organic 

 content required to build rich topsoil. Fortunately, we have such 

 an example in the Valley of the Nile, ancient "bread-basket" of 

 the world and reputedly the most fertile soil on the face of the 

 globe. Only in the more densely populated areas of China and 

 Japan do we find such a concentration of human beings drawing 

 their nourishment from limited areas of soil. For more than six 

 thousand years of recorded history the Valley of the Nile has 

 been densely occupied and under continuous cultivation, and this 

 without deterioration of the fertility of the soil. Here we have 

 an object-lesson in nature on mass-production of topsoil on a scale 

 of such magnitude as to enable us to envision the limitless pos- 

 sibilities inherent in the intensive propagation and utilization of 

 earthworms in the controlled service of man. We shall make a 

 brief descriptive excursion to the Upper Valley of the Nile. 



THE EARTHWORMS OF THE NILE 



In United States Department of Agriculture Experiment 

 Station Record, Vol. 27, No. 6, we find the following summary: 



Investigations carried on by the British Government in the 

 Valley of the White Nile in the Sudan indicate that the great 

 fertility of the soil of this valley is due in large part to the work 

 of earthworms. Observations are recorded from which it is esti- 

 mated that the castings of earthworms on these soils during the 

 six months of active growing season of the year amounts to 

 239,580 pounds (119.79 tons) per acre. 



The figures given in the foregoing quotation are almost un- 

 believably amazing to anyone who has made no study of the 

 activity and volume of work accomplished by earthworms. To 

 understand them, we must examine the source of the Blue Nile 

 and the facts in nature which make such results credible. 



The two source rivers of the true Nile White Nile and 

 the Blue Nile form their confluence at Khartoum, which in- 



