P. Manson-Bahr and N. H. Fairley 
59 
canal passes, may be widely distributed over the less densely populated 
agricultural areas of the Delta. The flooding of practically the whole of the 
Delta, which takes place annually, is no doubt a very potent factor in the 
spread of the disease. 
(2) The Canals at Abou Soueir. During the summer of 1916, a troop of 
Light Horse engaged in patrolling this sector was camped on the banks of the 
canal. In the hot evenings the men were in the habit of swimming in this 
canal, which is the second largest in the vicinity. It is deep enough for 
swimming and is from 40 to 60 feet in width, and its banks are lined with reeds 
and rushes. Investigation showed the presence of snails of the following species: 
Bullinus contortus, Bullinus dybowski and Planorbis boissyi. 
As in the Tel-el-Kebir group, so in this series also, two of the cases were 
found clinically to be double infestations, while four were infested with S. hae¬ 
matobium only. 
(3) Serapeum (Deversoir). Troopers of the Australian Light Horse 
stationed here were in the habit of bathing in the Suez Canal, which at this 
point enters the northern end of the Little Bitter Lake. After their swim, 
it was customary for a number of them to cross a belt of marshy land, about 
50 yards wide, for a final shower in the fresh water of an over-flow pipe from 
the sweet-water canal. For this purpose they stood in a small pool about 3 feet 
in diameter, by 2 feet deep, formed by the falling water. In this way most 
of them contracted bilharziasis. 
Subsequent investigation of the canal from which the pipe was leading, 
of the pool itself, and of the adjacent canals, revealed the presence of Bullinus, 
and of Physa, but only three specimens of Planorbis boissyi were found after 
an exhaustive search. Amongst the cases of bilharziasis from this zone, no 
infestation with S. mansoni was detected, though the faeces were most care¬ 
fully examined in every case. 
(4) The Fayoum. In 1917 a very considerable number of urinary cases 
(S. haematobium) occurred amongst the Yeomanry detachments ; the infestation 
being originally contracted in 1916. Eleven of these cases have come directly 
under our personal observation. Terminal spined ova were found in their 
urine, but lateral spined ova were never demonstrated in their faeces. 
In this district we found that Bullinus contortus was widely distributed, 
but Planorbis boissyi was never observed, after exhaustive search on two sepa 
rate visits to the ponds, ditches and canals of this oasis. 
The Village at el Mary. Before concluding this section the following obser¬ 
vations made at el Marg (Delta district) situated 12 miles north-east of Cairo 
will be included. 
Although we have no statistics of white troops billeted in this locality, the 
relationship between the molluscan fauna, and the types of bilharziasis occur¬ 
ring in that area, has been noted. 
