26 Report of the Bilharzia Mission in Egypt, 1915 



(i) To observe the conditions favourable and inimical to the life 

 of the free-swimming cercaria and the effect thereon of acid solutions 

 and other medicinal substances. 



ij) To study the bionomics of the special molluscan inter- 

 mediary, if obtained, for facts upon which prophylactic measures 

 could be formulated. 



An examination of the banks of the Nile to the south of and 

 around Gezireh, an island opposite Cairo, showed that, excluding 

 bivalves, there were very few living forms in the main stream. 

 Similar results followed from an examination of the Ismailia 

 Canal at Mataria, north of Cairo, and of the Giza Canal, on the 

 western bank of the Nile. 



A stud}' of a map of the environs of Cairo showed that there 

 was a large number of collections of water in the Zoological and 

 Botanical Gardens at Giza. With the permission of the Director, 

 Major Flower, these ponds were exhaustively examined and were 

 found to contain nearly all the described species of molluscs, with 

 one or two notable exceptions. With material from this source 

 a type collection of molluscs was made so that specimens brought 

 in later from infected areas could be rapidly compared and 

 determined. 



In the report of the ankylostomiasis campaign in Qaliubia it 

 was noted that a small travelling hospital had been stationed at the 

 village Qalama, thirteen miles north of Cairo and near the main 

 road to Alexandria (fig. 1). Of ninety-five inhabitants of this village, 

 forty-three had been found to harbour bilharzia. This small village 

 seemed, therefore, at first sight, a suitable place in which to make 

 an intensive study of the local molluscan fauna. It proved, how- 

 ever, more difficult o£ access than had been anticipated. There 

 was, too, a very large pond or birket which could not be thoroughly 

 examined. Finally, as will be noted from the map, the canal out- 

 skirting the village had passed through a number of other villages 

 after it took off from the main stream. Infection acquired in 

 Qalama might well have been due to infective larvse carried on from 

 a higher part of the canal, and not actually derived from molluscs 

 at Qalama itself. It was consequently decided to seek a more 

 suitable village, if possible {a) of easy access, {h) without a birket, 

 and (c) on a small canal coming almost directly off one of the main 

 supply canals. 



El Marg and the Maeg Canal. 



In the meantime, the Arab who had been for many years 

 attendant in the Department of Parasitology had volunteered to 

 bring snails from a place where he had been in the habit of 



