Prevention and Eradication 67 



of the announcement for the earlier part of the summer of 1915 

 is reproduced on the page opposite. It will be seen that after 

 running for a period of six days the water was shut off for fifteen 

 days. This system of " rotation " was enforced at the beginning 

 of April and was maintained until the Nile flood (as shown in 

 fig. 23) reached the Delta early in August. 



Under the Canal Act of 1894 severe penalties are imposed upon 

 those attempting to interfere in any way with the working of the 

 irrigation system. Imprisonment for periods up to two months 

 and fines not exceeding £20 may be imposed in cases of infraction 

 or disregard of the law. 



With the increase in the amount of water available which has 

 followed upon the building of the various dams and reservoirs, 

 new lands more remote from the Nile have annually been brought 

 under cultivation. 



Suggestions for Eradication. 



If some simple means could be found of stamping out the 

 molluscs in those situations in which the molluscs harbouring 

 bilharzia congregate and multiply not only would the incidence of 

 the disease be greatly reduced in the country, but the liability to 

 infection would also be greatly diminished in the large towns, e.g., 

 Bilbeis, on the main drains into which the small drainage ditches 

 discharge. The following proposals are based upon a study of 

 the problem in the district of which Marg is the 

 Drying. centre. The method, which seems applicable to 

 other parts of Lower Egypt, save, perhaps, those 

 in which rice is the chief crop during the summer months, utilizes 

 the present "rotations" in the supply of water enforced by the 

 Government from April until August. During periodical stoppages 

 of fifteen days the El Marg Canal became dry except for occasional 

 puddles (figs. 11, 12, 33, 34, 35). The molluscs were either stranded 

 upon the drying mud or collected in these puddles. It was found 

 that several days before the return of the water the Planorbis and 

 Bullinus taken from the dry bottom did not revive when placed in 

 water. Those in the small puddles of water had been able to 

 survive, the Planorbis being apparently more hardy than the 

 Bullinus. Had any attention been given to the alignment of the 

 Marg Canal so that small collections of residual water could 

 not provide a "carry-over" for the molluscs, these would have 

 been killed automatically by the " rotation " alone, just at the 

 commencement of their annual reproductive activity. The same 



