74 Bejoort of the Billiarzia Mission in Egypt, 1915 



molluscan carriers of Bilharzia during June and July. Taking 

 tertiary canals as supply units, it should be possible by adjusting 

 the rotation of crops so to group the land under cotton that, in a 

 given area, a third only of the tertiary canals need be used during 

 these months. The tertiary canals and drains supplying the other 

 two-thirds of the land would become thoroughly desiccated, and 

 their molluscan fauna completely destroyed. 



If the additional precaution of screening the tertiary canal head 

 were taken, the diminished supply involved by the mesh should be 

 compensated for by the insertion of a second screened pipe rather 

 than by the replacement of the original pipe by one of larger bore. 

 The screens would require periodical cleaning and supervision 

 throughout the year. 



The table of charaki lands given on p. 53 

 Lea^n^Years ^^°^^s ^^ feddans that a large area, varying from 

 year to year, is thrown out of cultivation when 

 there is a shortage of Nile water during the summer. Further, 

 the Government, under circumstances like those operating during 

 the present War, takes steps to restrict the area placed under 

 cotton. Whenever the land is brought into bare fallow from such 

 causes, efforts should be made as far as possible so to group the 

 incidence of fallow and cotton fields in a given area that the 

 transient financial loss directly contributes to a diminution in the 

 amount of Bilharziosis in the district penalized. 



The proposal to render cultivated land as dry 



Bilharziosis ^^^ ^^^ ^^ possible during the whole of June and 



Campaign and -^ , ^ c ll ^■ ^^ ^ ^^^ ■ 



Cotton Worm '^^^y ^^ ^ means oi attackmg the bilharzia-carrying 



molluscs would be very beneficial for the cotton 



fields themselves. The prominence of Egyptian cotton in the 



world's market is based upon its quality alone, and it has been 



shown that considerable deterioration follows a too copious supply 



of water. Moreover, when green and well-irrigated fields of clover 



are interspersed between the cotton fields during June, the cotton 



worms are provided with plenty of food and shade until the young 



cotton plants have produced sufficient foliage to receive them. If, 



on the other hand, the cotton fields can be kept dry, and the plants 



consequently hard and fibrous, millions of the cotton worms would 



perish. 



-D^_„ . The contamination of the water with infected 



XVOADS AND • J r 



Shipping. urine and faeces must continue so long as the river 



and main canals are the chief vehicle for transport 



in Egypt. There are still few main roads, and these generally 



