REPORT OF THE MALARIA EXPEDITION. 
17 
bctwi 
Such 
We recorded the following observations : — 
(i.) Anophcks larva- were never found in vessels of water, except in a single instance— a tub. 
(2.) A mangrove swamp fringing a part of the coast (Aberdeen Creek), far from human 
liabitations, contained no larva-, although there were numerous fresh-water pools on the edge of 
the dr^' land. Small fish abounded in the swamp. 
(3.) Part of a lariie swamp below Wilberforce Hill, and also one at Kiss\-, was examined 
by ourselves, assisted by several natives. Water lay to the depth of an inch or two 
clumps of grass, on a basis of flat rocks. Habitations were distant. No larvrf found. 
(4.) Owing to the hilh' nature of Freetown there are not many ponds or large poo 
as there are contained no larva? -although in several of them there were no fish. 
(5.) Rapid streams contained no larv;t-. 
(6.) Pools left dr)'ing after rain in watercourses, or other positions liable to scouring by 
heavy rain, seldom contained larv;i-- at least at the season when we were at P^reetown. 
(7.) Shallow puddles of rain-water, apt to dry up between the showers, seldom contained 
larva-. 
(8.) Puddles whicli lasted from shower to shower, but which were not liable to be scoured 
out by heavy rain, generally contained them. 
(9.) Pools on soil or rock fed by water oozing from the ground, and small slow runnels of 
water amongst herbage, usually contained large numbers of larv;t- -unless liable to scouring. 
Altogether we counted within the 
area of the map about one hundred prin- 
cipal pools containing Anopheles larva-. 
Generally speaking, we found the 
larva? in STtiall perma>ie>it pooh not Uohlc to 
scouring. We did not find them in vessels, 
evanescent pools, pools liable to scouring, large 
collections of water, and running strecnns. 
It woidd appear, then, that the 
larva- require certain conditions, namely, 
security from (i) desiccation, (2) scouring. 
To these should periiaps be added (3) 
security from small fish. 4. a i^irye Auopiwh-^ pool in ni;nisi(iL- .litLh. 
As may be surmised, then. Anopheles pools were not found on sloping ground where puddles 
either dry up very quickly or are apt to be scoured out h\ heavy showers. On the other hand 
they were frequently found on level ground. We did not find them on the hills surre)unding 
Freetown (though they were probably present in a few places) ; we did find them frequenti)- in 
the flattest and lowest parts of the town. 
The majority of the Anopheles pools were found in the ditches by the side of roads and in 
certain localities where many small streamlets ooze from the bases of the hills after rain. Otiiers 
existed in the course of the newly-made railway. Few were obser\ ed in the \'ards and gardens of 
houses. 
C 
