74 EGYPTIAN AGRICULTURE. 



mud on basin land to make up for the soil which has 

 been exhausted in growing the crops on his land. This 

 deposit is a necessary condition of continued fertility. In 

 Europe, instead of a yearly deposit, the farmer buys in 

 his land stones and rocks from which the weathering 

 agents provide him with a new supply of mineral par- 

 ticles. 



