Dr Stephens, The Prevention of Malaria. 
125 
search, or by making of pools if necessary. The same is true of 
all native villages, at least all those we have ever visited, for it 
is generally impossible to exclude local breeding grounds in the 
rains, and possibly in the dry season. It is a peculiar condition 
that in such native quarters mosquitoes may still be found even 
after a drought of some months. 
We may sum up by saying that Anopheles occur very widely 
distributed. Often it is difficult to detect them, but if a native 
village or small collection of huts occurs here they congregate even 
if breeding-places are absent or only exist during the rainy season. 
It is worth noting that to the breeding-places of the genus, which 
have been adequately described by many authors, we may add as 
not infrequent spots, native canoes and deep wells 30 — 40 ft. 
Accra. 
In the country around Accra we were unable to find a single 
natural breeding-place, but artificial ones — excavations made by 
the natives around their huts for various purposes — exist in many 
hundreds. With the advent of the dry season most of these pits 
become dry and breeding-places are now only found where the 
ground water is sufficiently near the surface to be reached by the 
deeper excavations (6 — 10 ft.). On the higher parts of the district, 
40 — 60 feet above sea level, in the dry season the ground water is 
not reached in the numerous pits existing everywhere and in con- 
sequence large areas are now free from breeding-places. 
Around the borders of the lagoons which are a feature of the 
coast the conditions are different. Here the ground water is reached 
within a few feet and in the driest season numerous pits dug by the 
natives along the margin of the lagoon contain Anopheles larvae. 
This condition shews that the effect of salt lagoons and low- 
tying salt marshes is an indirect one, as in the lagoons themselves 
larvae were not found. 
Lagos. 
Lagos is situated upon low-lying alluvium and is surrounded 
by extensive lagoons. The highest point of the island is not 
above 20 feet above sea level. A considerable tract in the centre 
of the town lies about 10 feet above sea level. This central 
area is approximately level but its margins sink rapidly towards 
the lagoons. Between this sloping ground and the lagoons there 
is a strip of land of varying width which lies almost at lagoon 
level. This strip is bounded by the 5-foot contour line. The 
heaviest rains are rapidly absorbed in the central elevated portion 
of the island so that in a few days after continuous rain all surface 
pools have disappeared. The subsiding water however emerges 
again around the borders of this tract forming a line of oozing 
water extending around nearly the whole island. It is here that 
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